Living Without the Internet

The appearance of articles on the blog slowed this month for a variety of reasons. Perhaps the most significant was a total internet outage. My terrestrial home internet service died due to obsolete technology, which required an upgrade rather than repair. I am too far from town to use my mobile data service. 

Living in the middle of nowhere is great for ham radio and not so much for connecting to the rest of humanity. Whether in the city or the country we've all leaned heavily on the internet during the pandemic. The recent loss of connectivity impacted my life in several ways, not least of which was amateur radio. Leaving everything else aside, I'll speak a little about the latter impacts.

Of course I could not access this account to manage the blog or check my email. Hence no articles. I did draft a couple of articles using an ordinary text editor, which allowed me to publish the most recent one less than 24 hours after being reconnected. All I had to do was copy the text over, include the pictures and embed links. It was quickly published.

Perhaps the oddest thing I worried about was this question: how will I know what's on the bands? No internet means no DX spots. I was also less aware of conditions since I couldn't check the solar and geomagnetic indices. That was when I rediscovered a feature all my rigs have. You may have come across it as well.

It works well, although it took some time to populate the band map. A better alternative was to flip on the amplifier and call CQ. Soon I was merrily making QSOs without the burden of spinning the big knob.

A more serious problem was my promise to give a Zoom presentation midweek. I could neither do the talk from home nor send the presentation out in advance. I resorted to the old sneaker net technology. I loaded several versions of the slides (PDF, PPT, etc.) onto two flash drives (for redundancy), filled a bag with A/V peripherals and drove to a friend's home with high speed internet. 

It didn't go well at first. Zoom is a resource hog and the laptop was page thrashing itself into oblivion. Due to physical distance imperatives only one of us at a time (both with masks) could hover over the computer to diagnose the problem. The rest of the time I was isolated in the room. 

We eventually gave up on using Zoom in the usual way. I connected to the conference by phone and one of the organizers flipped the slides while I spoke. That was a long 2 hours! Luckily I had emailed the presentation in advance to the organizers the moment I had an internet connection.

In case you're wondering, the presentation was about the design and build of my station. Above is an annotated panorama shot of the antenna farm that was taken this month and used in the talk. As the world's worst photographer I was lucky to snap this adequate shot. We are looking south from a point north of the 80 meter vertical yagi. I decided it was good enough that I uploaded it to QRZ.com.

I'll point you to the slides (PDF, 25 MB) with the warning that the presentation was not recorded and the slides may be cryptic on their own. I relied on maximum pictures and minimum words since that works best.

Installing the new internet service was a challenge. The installer's "tower guy" had quit and the subcontracted rigger wasn't immediately available. Hungering for connectivity I told him I'd do it myself. He agreed and drove over on Friday afternoon.

Unfortunately the small tower I bracketed to the side of the house a few years ago didn't give us enough height to reach my contracted 5 Mbps download speed. With extension pipes I had on hand I could raise the radio/antenna unit to no more than 45' (14 m). The 6 nearest towers are approximately 20 km distant, and only 2 or 3 of those had acceptable signals due to terrain and foliage.

Per Shannon, bandwidth is proportional to data rate. However as you increase bandwidth the SNR declines. Although I am a little out of date with my telecommunications technology knowledge I do recall enough about LTE to know how it dynamically trades off data rate (bandwidth) and reliable connectivity.

We needed more height. I reluctantly agreed to put the radio/antenna on the Trylon tower behind the house. The maximum height I was willing to risk was 60', a little below the rotator plate. Any higher would create a problem for operation and maintenance of the rotator and antennas above.

That worked. He patiently hunted for the best tower, with me adjusting the azimuth and (surprisingly) elevation. He got me more than 7 Mbps download speed, and about 1.5 Mbps upload speed. I will no longer have to leave home to use Zoom. With the tools and equipment he sent up the tower I completed the installation while he confirmed signal stability. He connected the surge protector to the tower ground.

The cable from the tower base to the house was buried two days later. Instead of a trench I cut a slit through the sod and pushed the cable down about 3" into the slit. That's a third cable run from the Trylon to the house. 

I fed the cable through the second hole into the house that I made for the second trench and the 6 meter transmission line. It's a very neat installation.

Worried about EMI I asked about the cable he was using. He reassured me that he used Cat6 shielded cable throughout. As of this writing I have not noticed any noise problems while receiving with the antennas on the tower. I will have to do a kilowatt test to ensure that the internet service is not disrupted by my transmissions.

I am considering the installation of two lengths of steel stock on the tower to protect the internet equipment from accidental bumps during antenna and tower work. Damage could be costly and inconvenient. The pile of ferrites I distributed along the unshielded Cat5 cable for the previous service will be reclaimed. They appear to have survived several years of UV and weather.

One remaining question is what to do with that small house-bracketed tower? I'll leave it where it is until I can come up with a plan. It would be a shame to see a perfectly good tower go unused.

Station Improvements for 6 Meters

After the 2020 sporadic E season I planned improvements to my 6 meter capabilities in 2021. Although the antenna is unchanged there are several items recently completed that should make the upcoming sporadic E season a successful one.

• Adjust the yagi
• New low loss feed line
• Power

The redesigned Cushcraft A50-6 continues to perform well. However when it was raised a few years ago the carefully adjusted gamma match did not escape unscathed. As a result the SWR at the shack end of the coax ranged between 1.5 and 1.8 over the important band segment of 50.0 to 50.5 MHz. The rig's ATU handles this well, though at a cost.

First, there is additional transmission line loss due to the mismatch. That -0.3 db is in addition to the -1.3 db matched loss of the 40+ meter run of LMR400, RG213 and some LDF5. The calculated total loss is therefore about -1.6 db. 

The ATU is not loss free. An estimated ATU loss of -0.2 to -0.5 db is as bad as the line loss due to the mismatch. HF rig ATUs tend to have high loss at 50 MHz so my estimate is within reason. Let's guess that it's -0.3 db, thus bringing the total mismatch loss to -0.6 db. The total system loss is -1.9 db. That is more than enough to hurt when conditions are marginal. The loss needs to be lower.

With the help of a friend the antenna was dropped to the ground for service. I discovered more problems than just the gamma match. Several of the hose clamps holding the boom sections were loose and allowed rotation of the tubes by hand. These were tightened. Weatherproofing of the coax connector was not the best so I upgraded that as well. Fasteners on my original A50-6 are not stainless so those required cleaning and other maintenance.

The gamma capacitor showed weathering effects. It is similar to RG213 with the shield removed but with a plastic that does not age so well. It is a known problem with the Cushcraft "Reddi-Match". After the antenna was adjusted I covered and sealed the exposed section of the capacitor with two layers of Scotch 33+ tape.

Adjusting the match was a puzzle at first. Dimensions of the elements and the gamma match are not at all according to the original A50-6 or the revised and optimized A50-6S. It's a good thing I keep this blog since I documented my redesign of the antenna. Finding those notes in my paper records is not easy.

Tuning was done at λ/2, which on 6 meters is a comfortable 3 meters (10 feet) above ground. This is more than high enough for reliable adjustment. When I last adjusted the antenna I had it closer to the ground but pointing straight up. It is easier to set it up horizontally than vertically, although both methods work well. A step ladder was all I needed to reach the elements and gamma match. I had to move away from the antenna to make each measurement since our bodies alter antenna behaviour as these shorter wavelengths.

In light of the dominance of FT8 on 6 meters I centred the SWR at 50.3 MHz. It is below 1.2 from 50.0 to 50.5 MHz, rising to 1.45 at 51 MHz. This is perfect for my operating preferences of CW, SSB and digital modes. The SWR is slightly better in the shack due the small loss of the improved transmission line (see below).

The antenna was raised with a tag line this time so that it didn't bump into the tower. The gamma match did not fall out of adjustment. With a step on the mast I placed it almost a little higher that it was before, which should further reduce the already minimal interaction with the XM240 below it.

Before winter moved in last year the main run of LMR400 was replaced by LDF5-50 Heliax. The matched line loss is improved by 0.5 db over LMR400. With negligible mismatched line loss the total loss is now calculated as -0.8 db. Therefor the total loss improvement -- matched loss, mismatched loss and ATU loss -- is 0.8 db. That's total system improvement of 1.1 db compared to before. I consider this to have been well worth the effort.

Actually, coax loss was not only calculated. I measured the new sections with a VNA to confirm insertion loss. The VNWA plot is of the 9' RG213 rotation loop. Although the coax is old it was properly stored and has the loss predicted for new RG213 (S21 calibration is off by -0.01 db). 

The impedance variation is small and not unusual. I get similar results for the LMR400 sections of the coax. In my experience, Heliax is more consistently close to 50 ohms, probably because it is hardline and less likely to exhibit small deformations. Then again, maybe I really should do that recalibration!

The final area of improvement is power. I now have an amplifier that will do 1 kilowatt on 6 meter FT8. It is the ACOM A1500. I will have more to say about this amplifier and why I chose it in a future article. Sporadic E openings on long DX paths are brief and weak. I need every advantage to improve my results. 

Now that I have over 90 DXCC countries worked on 6 meter FT8 (81 confirmed) new ones don't come easy. Over the past few seasons I have missed opportunities to work many countries because they ran QRO (I could copy them) and I did not (they could not copy me). Despite having the amplifier available, I will not operate QRO full time, but I will not hesitate to turn it on when the DX beckons. My objective is to pass 100 countries in 2021.

The new coax for the 6 meter yagi is not switched: it runs directly into the shack to one of the antenna ports on the A1500. The A1500 conveniently allows port switching when the amplifier is off. This is handy because sporadic E openings are sporadic (of course!) and I will be able to operate on HF via the second rig and amplifier while monitoring 6 meters with WSJT-X and even working stations on HF and 6 meters concurrently. No longer will I be restricted to one or the other. 

This flexibility is nice to have although I don't know if I'll actually do it. Actually, the more important reason is to avoid consuming a port on the 2×8 antenna switch. Until now I used one of the ports for 160 meters in the winter and 6 meters in the summer. That is no longer necessary and it gives me full time access to the 6 meter yagi year round. Perhaps its availability will encourage me to take advantage of winter sporadic E propagation.

All I need to do right now is wait and monitor for the start of the sporadic E DX season. Openings will become increasingly frequent during May. I hope to see you on the Magic Band.

East-West Reversible Beverage

One slow step at a time my Beverage receive antenna plan is steadily progressing. As of this week I have 3 of the planned 4 reversible Beverages in operation. The latest is the east-west Beverage, and the existing ones built in 2020 are the northeast-southwest Beverage and the north-south Beverage. 

Like the NE-SW Beverage the new antenna is a 2-wire electrically reversible design. As I watch the weather batter the N-S coax (RG6) Beverage I am increasingly of the opinion that an open-wire Beverage is more reliable and easier to maintain. Coax requires substantially more mechanical support since it cannot take much tension. It droops and is more susceptible to wind, ice and falling tree limbs. Although it continues to work well I can see that a day will come when it will have to be replaced.

Regular readers may recall that this most recent Beverage project began months ago. First the area had to be surveyed to find the best location. Next came the clearing of the bush. That turned into a frustrating exercise because I didn't mark one of the termination points (big tree) and I cut the wrong path. Correcting that error wasn't difficult because the chosen route has relatively few trees and bushes that had to be removed.

At right is some of the cut brush alongside the (still frozen) swamp at the east end of the antenna. There are smaller piles of cuttings all along the route. These several acres of bush have no use so I can leave it there to decay naturally.

Antenna specifications

The Beverage is 156 meters long. I measured it to be certain rather than estimating from the dimensions of the property. The west end is in the tree line about midway along the north-south Beverage. The east end is just inside the swamp that I share with several neighbours. 

I could have made the Beverage longer by venturing into the swamp. The first meters of the swamp are frozen in winter but range from damp to standing water at other times. Maintenance would be so unpleasant that I ventured no further east. The performance benefit of another 20 meters (to make it 175 meters) isn't worth wading through the muck.

Since the NE-SW Beverage works so well I made this one the same. The wire is AWG 17 aluminum electric fence wire vertically spaced 4" (10 cm). Height is a pretty consistent 2.5 meter, and slopes downward starting 10 meters from the eastern termination. With snowmobiles, hunters and deer becoming more common I don't dare place the Beverage any lower. I warn my neighbours what's hiding in the bush when I allow them access. The aluminum wire can be difficult to spot if you don't pay close attention.

Supports

Most of the selected path is open ground or with trees too small or not in positions to act as supports. This makes the antenna route easier to use and maintain but requires construction of supports. I used standard ¾" PVC pipes spaced no more than 20 meters apart. Rebar and other scrap length of ~½" metal rods peg the pipes to the ground. Since they tend to sink into the soft ground I later added small preserved wood platforms, pierced to pass the peg.

The picture below shows the variety of supports used for the Beverage.

The first picture (left) show the westernmost 40 meters of the antenna with the tree anchor and two of the PVC pipes. PVC pipe is not strong, but it doesn't need to be. The load is primarily carried by wire tension, with the pipe experiencing very little vertical and lateral force, even in a strong wind. In a way it's the wire that's holding up the pipes! Wood or metal posts with insulators are alternatives. 

Slits sawed into the pipe hold the antenna wire and wire ties hold them there. An advantage of PVC pipes is that they can be easily extended by inserting a short length of the same pipe in the coupling flare at one end (third from left).

Yes, Beverages can cross without coupling. The resistance loss (inefficiency) lowers the mutual coupling to a very low value. In the crossing picture (second from left) the NE-SW and E-W 2-wire Beverages are only 6" apart. The E-W Beverage crosses the N-S Beverage at the west anchor point, as we'll see later.

For the several trees used as supports I used PVC and electric fence screw-in insulators, shown fourth and fifth from the left, respectively. Between supports PVC spreaders (on the right) help to maintain a consistent wire separation of 4" (10 cm). They are made by quartering a 5" length of PVC pipe, cutting ½" slots for the wires and drilling holes for wire ties.

The crossing of the N-S coax Beverage is at the west termination. This is perfectly fine. What you must avoid is terminations at the same location because the proximity of the grounds will degrade the patterns of both antennas. The left picture shows plastic egg insulators, dacron rope and nails on the tree as cleats to support and tension the wires.

A spreader was added at the insulators to keep the wires in position as they are pulled downward to the head end electronics. Two screw insulators on the tree and another spreader ensure the wires touch nothing along the way, including each other. A cable tie holds the box to a length of pressure treated lumber at a height that will keep it out of the snow most of the time. The board is nailed to the tree.

After several trials a gap in the subsurface stone, rock and tree roots was found to pound in the 4' copper plated ground rod. All the Beverage grounds have now been upgraded to that shown on the right. The black AWG 18 wire has a spade lug to connect to the box. On the ground rod end a thin copper plate is drilled and soldered to the wire. A stainless hose clamp bends and holds the plate to for a high surface area copper on copper bond.

Reversing electronics

The head end electronics is identical to that of the other 2-wire Beverage. The only difference is its cleaner layout using a larger prototype PCB. Compare the two below.

I labelled the SPDT reed relays and whether each is normally on (NC) and off (NO). I made west the default direction that, because of my contest activity, west will be used more often than east. The relays are powered by +12 VDC on the coax -- RF and DC are separated by capacitors and RF choke -- to reverse the direction. The unused direction is terminated to a 75 Ω load to prevent reflections that would destroy the unidirectional pattern.

A 7:3 transformer uses the 2 wires in common mode for the east direction. It is fed via the centre tap of the primary winding of the 12:4 balanced transformer. The 12:4 transformer receives the differential mode of the antenna wires for the west direction. A reflection transformer (not shown) at the east termination converts the common mode coming from the west into a differential mode signal, using the antenna wires as an open wire transmission line. More detail can be found in the article on the NE-SW Beverage.

Feed line

I purchased a 152 meter (500') roll of inexpensive RG6 plenum coax, about half of which was used to connect the new Beverage to the remote antenna switch. It is simply lying on the ground. There are several issues I had to deal with for such a long run of coax:

• Animal damage, primarily deer, rodents and (yes) humans
  
• Interactions with the N-S Beverage
• Ease of installation and maintenance
  

I have enough unused bush that there are route choices. A friend help me cut a narrow path through the vegetation. On bare ground the coax was placed alongside rocks and trees. Trampling by deer, snowmobiles and other other vehicles is thus avoided. There is no good protection against rodents other than gel-filled cable which is expensive and usually unnecessary. I have had no trouble with rodent damage with cables on the ground, and that is the experience of many hams. Since it can happen I prefer cheap coax that I don't mind replacing should damage occur. Black jacketed cable is recommended since its tends to be more resistant to the elements regardless of its specifications.

I routing the coax out from under the N-S Beverage as soon as practical (less than 10 meters along) and kept it 5 to 10 meters distant, running roughly parallel on the east (bush) side. At the south end the coax turns west, where it lies close to the coax from the N-S antenna for 10 meters on the way to the remote switch. Initial listening tests indicate little or no discernible pattern degradation of the N-S Beverage in both directions. I am prepared to insert chokes along the coax should interaction become apparent.

There are a couple of places where the coax crosses openings in the tree line where I need to walk and vehicles may cross. I will bury those several inches below grade as I did for the other Beverages.

There is no picture to show the coax in the bush since it is really difficult to get one that isn't fuzzy or confusing. Bush photography is difficult and I am no good at it.

Debugging: direction selection and one dead direction

The new Beverage plugs into a port on my remote Beverage switch. No other work needed to be done to make it available for use at the operating desk. Or so I thought.

When I turned the rotary switch to the reserved position for the new Beverage all I heard was silence. As I've learned over the years the best approach to a difficulty of this type is to sit and think for a few minutes to review all the steps of the construction and testing. 

Suspecting something simple I opened my home brew antenna selector and traced the wires. I discovered that I had not connected the third or fourth ports to the rotary switch. A few seconds with a soldering gun and atmospheric noise was heard from the receiver. 

In both directions the signal level was comparable to the other Beverages. That was reassuring. A quick check on 30 meters (the lowest band open at the time) confirmed that it was reversing correctly and that it had directivity in both directions.

A test with an antenna analyzer showed that it was switching and that the SWR was reasonable though a little high in the west direction. I won't reproduce the SWR scans since they are very similar to those of the other 2-wire reversible Beverage, linked to earlier in the article.

After sunset I gave it a try on 160 meters. The first station copied was C92RU in Mozambique. Their signal was copied well with the new east Beverage and not with the adjacent south and northeast Beverage directions. C9 is due east so this was a promising result. Two evenings later I was pleased to work them.

Unfortunately the west direction didn't work so well. Unlike earlier in the day there was silence. A check with the antenna analyzer confirmed that it was not working in its default direction but all was good in the reverse (east) direction.

The next day I made the 250 meter trek to the head end to see what was amiss. I suspected a loose wire at the head end or the reflection transformer at the east end of the Beverage. There was no obvious fault so I removed the reflection transformer for testing. It took some time until I discovered an intermittent short between the windings. 

I replaced the outer winding, successfully tested it and put it back in the box. We have a few days of rain forecast so there may be a delay taking it back out to the swamp. I saw no reason to delay this article, so I am ending on this hopeful note.

Next steps

The new Beverage direction selector is a work in progress that has been slowed by too many other projects. I continue to use a rotary switch to select the Beverage and a toggle switch to reverse direction. It's awkward but I won't be using it very much over the summer months. Work on the new selector will have to be squeezed in on rainy summer evenings so that it's ready in the fall.

It's a shame that the new Beverage is ready just as the winter top band season is ending. It would have come in handy to more reliably copy the recent A25RU DXpedition. They copied me better than I copied them since I had no receive antenna pointed their way. 

Next month is the annual rolling up the radials ritual for my big vertical. Until early fall I must use a relatively poor base loaded 160 meter vertical. If all goes well my 160 meter station will be significantly improved for the 2021-2022 top band season. In addition to the extra two Beverage directions I have a plan to improve my transmit antenna efficiency.

The last Beverage in my 8-direction receive array is for NW-SE. It is last because from here these are the least useful directions. Because of that and the problem of finding a good route for it in the bush I am contemplating alternatives. One possibility among several candidates is a reversible end fire array using small verticals.

This is the last of my winter antenna projects. Over the warmer months my attention turns to the towers to build 10 and 40 meter antennas and to relocate a few antennas to more permanent locations. I've been moving antennas quite a lot since moving here in 2016 as towers were raised and mediocre antennas were supplanted by better ones. Work on the antenna farm never ends, and that's how I like it.

The Challenge of Wire Yagis is...Wire

I receive many inquiries about wire yagis. This corresponds well with the blog statistics since the most popular article over the 8 year run of this blog is the 40 meter 3-element wire yagi. There are several other related articles that are almost as popular. This isn't surprising because for most hams a yagi for 20 meters and higher bands is not difficult to buy and install, but once you go down to 7 MHz the size of a rotatable yagi, even one with shortened elements, is beyond possibility for most hams. 

Yet there is a desire for better performance on 40 meters than a simple antenna like an inverted vee, vertical or loop. A wire yagi is enticingly within reach. Few bother to contemplate multi-element, higher performance antennas on 80 and 160 meters and, again no surprise, those articles on the blog are far less popular. Many are willing to try on 40 meter wire yagis because they are easily supported and inexpensive, and with a little ingenuity can be electronically switched between its two broadside directions.

In reality it is never quite so simple, as many have discovered. Many hams abandon the project midway through. One of the difficulties is that many hams do not really understand yagis and their subtle complexities. They do not have the technical knowledge, the required test equipment, don't know how to use the equipment or don't know how to interpret what they see. A 2-element yagi is not twice as difficult as a dipole or inverted vee: it is closer to 10× more difficult.

That said, I don't mean to discourage anyone from embarking on a project like this! It can be a very satisfying experience, from the knowledge gained to the on air results. I built my first 40 meter wire yagi over 30 years ago and I got it working despite my (then) limited knowledge of antenna theory, nothing more sophisticated than an SWR bridge for test equipment, ELNEC software (precursor to EZNEC) and a lot of motivation. 

The antenna worked and I was hooked on the potential of these deceptively complex antennas. Readers may be surprised to next hear that I've only ever had two of these antennas. Many designs I did for other hams or they were modelled and never built. I've learned a lot on this journey.

In this article I want to focus on one particularly fundamental challenge of wire antennas: the wire itself. This is the one thing almost everyone takes for granted and should not. A lot of the trouble people run into is that they don't understand the surprisingly large impact of wire specifications and usage on the project. You can easily ignore or remain blissfully unaware of these issues with a single element antenna -- test, prune and you're done. Yagis are not so forgiving.

Before we jump in, a word about the common rotatable yagi with aluminum tube elements. In contrast to wire yagis these antennas are can be modelled to an absurd degree of accuracy and predictability. I recently gave an example of this phenomenon. NEC2 supplemented with an algorithm to correct for stepped diameter (telescoping) tubes works extremely well. 

Whether you can model it in free space or a modest height above ground the result are reliable, and indeed almost exactly the same. Commercial vendors love this since individual hams don't have to adjust their products as long as they're installed at a modest height of at least, say, λ/2: approximately 30' (10 meters) for a tri-band yagi.

The following is a brief list of wire difficulties builder of wire yagis are sure to encounter. All will be discussed in this article. After giving you lots to worry about I'll make proposals on how to deal with the uncertainties when building wire yagis.

• Insulation: material; thickness; stability; or bare wire
  
• Material: copper soft drawn vs hard drawn; copper plated wire; other conductors
• Conductor diameter
• Stranding: solid; number of strands
• Sag and tension
• Wire termination method
  

Let's begin with must seem to be a elementary description of what a wire is. The following diagram is of a THHN electrical wire often used in Canada and the US since it is ubiquitously available in bulk and usually at good prices. It is from a randomly selected web site. There are of course countless varieties of wire in the market, and this is no way is a recommendation to use THHN.

Wire material and construction

For almost all electrical wire the metal is soft drawn copper. Unless alloyed or hardened copper is a soft metal. Put it under tension and it will stretch, and in the process it will also harden. Do it under controlled conditions and you will have made less stretchable hard drawn copper. Some hams do that. It's a good idea although I've never done it. If you do there will be a slight diameter reduction of (usually) no more than one AWG number. Hard drawn copper wire for antennas is commercially available at a higher price than electrical wire.

As soft drawn wire stretches the resonant frequency will be lower due to its longer length. Under moderate tension and the load put on the wire by wind and ice you will find that the antenna will have to be adjusted because it stretches and sags. Expect to do it more than once.

Stranded wire will stretch more because the individual strands do not lie quite flat against each other. Under tension the strand spirals will draw inward and lengthen. This is independent of the each strand stretching as it hardens. Guy strand and rope compress in a similar fashion. The impact of this behaviour on wire yagis is quite and can almost always be ignored.

Another problem with stranded wire is that for the same gauge the rate of corrosion is higher. Chemical reaction rate is in proportion to the surface area, and that is always higher for stranded wire. 

On the positive side, stranded wire is more flexible. Some believe their wire antennas survive better for that reason, although I haven't noticed any difference from solid copper. Of more immediate concern is that careless handling of solid wire is more likely to result in kinks that will weaken the wire. Copper will break from the fatigue of repeated bending. Repairing just one kink will weaken the wire.

I used to believe stranded wire was better and that's what I used. Like many other hams I now build wire antennas almost exclusively with solid wire.

One of the worst choices in my experience is bare stranded copper plated steel. Copperweld and similar products corrode faster and are prone to rust as the copper plating develops fissures. Sanding the corroded wire can remove the copper plating. On the other hand it takes tension well, and that allows construction of predictably stable wire antennas. I know hams who are happy using plated wire for their low band antennas that have survived many years.

Non-copper wire such as aluminum and galvanized steel are rarely used for HF antennas. The lower conductance of aluminum and zinc for low radiation resistance wire yagis is not desirable. There are other concerns I will pass over, such as skin effect (for any plated conductor) and robustness. Copper wire copper plated wire are almost always the correct choice for wire yagis.

Wire diameter

Wire diameter affects reactance and therefore affects the resonant frequency. As the wire thins the resonant frequency rises, and on 40 meters every wire we use is thin with respect to wavelength. As an example, a tube element of 25 mm (1") diameter that is resonant at 7.1 MHz will resonate at 7.2 MHz when made from 2 mm diameter wire (AWG 12). We cannot ignore diameter for our wire yagis.

The ratio of wavelength to wire diameter is the K factor. At 7 MHz the K of the 25 mm and 2 mm elements are 0.0006 and 0.00005, respectively. These are small numbers. On 10 meters they would be only 4 times larger. There's no escaping the very small K factors of wire antennas on all HF bands. Be sure to specify the correct wire diameter in your NEC models to avoid mistakes.

Insulation

In the THHN link above you will find a table containing specifications for the insulation layers. One of the words used should give you pause: nominal. Insulation dimensions will vary for many reasons: manufacturer; forming equipment; business decisions; among others. Provided the wire meets critical requirements like voltage rating, weather and environment, failure rate, temperature/loss at rated current, etc., the product will almost always be accepted. 

Electrical wire is not intended for antennas so expect surprises with the insulation. I've tried using calipers to measure insulation thickness with little success. Insulation is compressible and difficult to make straight enough for the calipers to seat properly. I have done better using the published tables for my EZNEC models despite the variability.

Insulation is a critical factor for antenna design, so we must deal with the details. Since we can't rely on the insulation specs we must adapt to them. The biggest concern is velocity factor (VF). Insulated wire typically has a VF of 0.97 to 0.995. Hence the rule of thumb to shorten a wire antenna by 0.5% to 2%. This is not enough accuracy for yagis. A 1% change is 70 kHz at 7 MHz, and that is unacceptable for those aiming for performance. I assume that anyone building a 40 meter wire yagi has performance as an objective, since otherwise why bother investing the time and effort.

A nice thing about insulation is that corrosion is slowed. Moisture will still get in there if the ends are not sealed, and as the antenna wears under environmental pressure the nylon shell will break off (increasing the VF) and the base insulation will develop micro-fissures. Avoid the more colourful wire and always choose black since the (typical) carbon black pigment resists UV deterioration better than other pigments.

The VF of bare wire is far more predictable, at the price of corrosion due to complete exposure to the weather. If you live in an area with high levels of air pollution or near a sea or ocean the rate of corrosion will accelerate.

NEC2 supports specification of insulation for wires. Use the specifications of the wire if you can find the needed data. The important ones are the insulation's dielectric constant and thickness. The dielectric constant is determined by the insulation material. When I am not sure I use 3.5, and it is usually close enough.

Termination

The method used to secure the ends of a wire affects its electrical length. It is easier to get accurate results with bare wire than insulated. 

Consider the termination at right. Since it is insulated, the entire wire length contributes to its electrical length. That loop is next to impossible to model with NEC2. The wire loop is too small relative to wavelength to break into segments.

The actual end of the wire is the true end and so the small loop has a measurable effect. Since the current magnitude is close to equal in the loop and the phase is opposite on opposite sides of the loop, there is field cancellation that partially negates the wire length comprising the loop. But, as already said, it's difficult to model or predict.

Predictability requires stripping the insulation at the termination and wrapping the bare wire loop onto itself. Now the electrical length is to the outer edge of the loop. It is also easier to make a wrap from bare copper wire that will hold under tension. Plastic insulation is springy and can unwrap -- it has happened to me -- and it's worse with stranded wire. If you leave the loop insulated it is important for consistent results (after calibration, discussed below) that the insulator type, loop size, and length or the wrapped wire be the same on all elements. Follow the same procedure at the centre insulator.

Tension

Sag matters in a wire yagi since it lowers the interior angle at the apex. That increases the resonant frequency and lowers the radiation resistance due to increased field cancellation. 

Under tension wire will stretch (see above) and the resonant frequency will be lower. Unfortunately the frequency lowering action of wire stretch does not equal the increase due to sag. You'll have to adjust the yagi or its elements when either or both occur.

Some numbers will help. Making soft drawn wire hard drawn with tension can increase its length from a few percent to as high as 10% before it breaks. Soft drawn copper under ordinary use will stretch less than that. This is not a minor consideration especially as you go down in frequency and a wire antenna is long and heavy. Wire has to support its own weight in addition to support tension. Consider that 1% at 7 MHz is 70 kHz. That's a lot for a restricted bandwidth antenna like a yagi.

Tension is often more than you might imagine. A few years ago the ground anchor of my T-top vertical for 160 meters pulled out of the ground when the wind speed was 70 to 80 kph. It was just a wood stake pounded into the ground. To prevent further damage I went out in the wind storm to pound the stake back into the ground. I couldn't. The wind load on ~47 meters of 14 AWG insulated wire and the rope catenary was too high. I temporarily tied off the stake instead. After the storm I put it all back together and noticed only a small shift in the resonant frequency. For a single element antenna it was not a problem, but for a yagi it might be.

Straight lines are easy to draw and in modelling software. The ideal angle we get is not the reality. The interior angle of the antenna will be smaller due to sag. Modelling the curve in the wire is quite difficult and nigh impossible to get it right, and this is another problem setting the resonant frequency accurately.

We have a few options available to deal with sag:

• Increase tension: That may stretch the wire and you'll soon be repeating the procedure. Choose stronger wire or avoid excess tension.
• Pull the ends of the vee farther apart: With the inevitable sag you can get closer to the desired interior angle.
• Include a centre tube: Sag is moved outward from the high current center to where its impact is less.
  

Radiation intensity is in proportion to current and that is highest at the centre of a λ/2 antenna like an inverted vee. That is why centre sag is significant. Removing sag improves performance by way of a higher radiation resistance and higher height for the average current. The centre tube option nicely deals with the problem even if it isn't very long. As a bonus, as tension changes the tube will rotate from its horizontal position. It's a highly visible indicator that you have work to do. 

On the negative side, the tube must be split for the driven element and for the switching of a reflector coil. Split wire elements are much easier to build.

If there are no convenient supports for the ends of all elements in a wire yagi with 3 or more elements it is possible to use a catenary rope to support the ends of all the elements. Equalizing tension to avoid excess sag can be difficult. Here is a picture of such a catenary in action that someone brought to my attention. I've contemplated one of these to avoid ground anchors in farm field surrounding my towers for any wire yagis I might build at this QTH (none so far).

A further consideration for setting and maintaining wire tension is selection of the rope. It should not expand or contract in any weather and it should be UV resistant. Black dacron is a good choice that is available from many amateur radio retailers and suppliers. I have a large spool on hand for wire antenna project. 

Avoid polypropylene, nylon and natural fibre ropes that will not fare well outdoors and that will stretch with the weather and with age.

Since tension adjustment is unavoidable you should use knots and devices that allow easy release and adjustment. I am not very knowledgable about knots and mechanical tensioners so I will make no recommendations. I use a combination of knots and rope cleats.

How to get it right

It may sound counter-intuitive that wire yagis with 3 or more elements are easier to design, build and adjust than those with just 2 elements. One reason is that 2-element yagis have narrow bandwidths for gain, F/B and SWR. A second reason is that reversing a 2-element yagi requires a more complex switching system for symmetrical performance.

Yagis with 3 or more elements have simpler switching and the bandwidth is larger. A tuning error of 50 kHz is far less detrimental, to the extent that you might not notice it. You will notice it with a 2-element yagi. The Moxon rectangle variety of 2-element yagi does better with its larger F/B and SWR bandwidth. Its gain bandwidth is the same as a conventional 2-element yagi. If we want the best gain at our favourite frequency with a 2-element wire yagi or Moxon the tuning must be accurate.

How can we adjust a wire yagi to get the promised performance? As we've seen above, the variability due to wire choice and usage is surprisingly large. I follow one of two approaches: calibrate the wire or calibrate yagi performance markers. Let's look at both.

To calibrate the wire we first construct an inverted vee (assuming the yagi will use inverted vee elements) using the wire of your choice. Make the centre and terminations as identical as possible. Details matter. Attach coax of known length and type to the centre feed point. The coax should run straight down or orthogonal to the inverted vee to minimize coupling. Use a common mode choke to prevent the coax from becoming part of the antenna. Put tension of the ropes and measure or calculate the interior angle. Note the heights of the apex and the lower ends.

Measure the impedance of the inverted vee. Use a application like TLW (packaged with the ARRL Antenna Book) to transform the impedance to what it is at the feed point. Shift frequency up and down as required until you locate the frequency at which the feed point reactance (X) is 0 Ω. That's the resonant frequency. Do not adjust the element length at this time.

Construct a NEC2 model of the inverted vee. Take care that the dimensions exactly match the built antenna, for the layout and for the wire diameter and insulation. Set the real ground to what you believe you have in actuality -- medium is a good choice for most horizontally polarized antennas even though many urban/suburban locales have worse ground than that. 

The resonant frequency of the model should equal that of the antenna measurement, but almost certainly won't. If they are far apart, stop to ask yourself why. Investigate and redo as needed. If the frequencies are close adjust ground constants or wire insulation properties until the resonant frequencies agree. You will have to use your judgment. Don't just enter numbers at random!

Move the model to free space and locate the resonant frequency. It will have moved because the ground coupling is absent. Note the difference and adjust the real antenna so that its resonant frequency differs from your desired centre frequency by the same amount (the frequency could be higher or lower). This will get your real inverted vee close to what its resonant frequency would be in free space. This is the procedure I am using to calibrate the elements for my planned 40 meter 3-element rotatable yagi.

As noted many times in this blog and elsewhere, a yagi at a modest height behaves as if it were in free space since there is significant field cancellation in the vertical direction. You could say it doesn't "feel" the ground very strongly, or at least its effect becomes small in comparison to the mutual impedance between the yagi elements. 

Unfortunately it is very difficult to measure each element when it is in a yagi due to that mutual impedance, so we do it indirectly using the method described. All the elements can now be scaled from the calibration data. You must be careful to use the exact same wire and construction technique for the calibration to be effective. An extra inch of insulated wire on the end egg insulator is an inch too much.

The second calibration method is done after the fact. First, build the complete yagi. By whatever means get it close to the desired frequency range as possible. Err on the long side because it's easier to prune elements than to lengthen them.

Work with a friendly ham located broadside to the antenna (in the direction of the main lobe) to find the frequency of maximum F/B. Should that be inconvenient, an alternative is to find the frequency where the feed point resistance component of the impedance (Z = R + jX) is minimum. On the computer model find that frequency. The difference is the tuning error. I used this method to adjust my long boom 15 meter yagis.

To adjust the antenna, scale all elements by the calculated frequency ratio. For example, if the measured frequency of minimum feed point resistance is 7.350 MHz and the desired frequency is 7.275 MHz the ratio is 1.01 and the elements need to be 1% longer.

Dealing with uncertainty

I have been asked several times for the wire dimensions of the wire yagi designs found in this blog. My answer typically resembles what you've read in this article, and I can tell you that it satisfies few of them. The point is that I should not and cannot specify the lengths for the elements of a wire yagi! I don't know your wire, your environment or your construction techniques, and those are critical parameters for the reasons explained in this article. 

Sometimes I have shown lengths, and when I do I also specify the wire and mention that you will very likely have to adjust the lengths. I sometimes wonder if the message gets through to many readers. All I can do is provide guidance and show what can be achieved by those who put in the effort.

That, really, is the point of this article: wire yagis require work! If you must have an exact construction guide you should look at alternatives. Despite the challenge, building a wire yagi can be very rewarding, and educational. I enjoy the learning experience. Maybe you will, too.

Case of the Missing HF Spice

One consequence of the pandemic has been a dearth of DXpeditions. You might therefore think that the DXpeditions or other moderately rare DX stations would receive more attention than usual. This is what economists call supply and demand: there is less supply so the demand should be high because we are spending far more time at home. That is, we should be willing to pay a high "price" for the rare DX.

That hasn't happened. When these stations did appear the pile ups were not deep. For many of them I found it took just one call to get through. As regular readers know I do have a few big antennas, and that does make it easier. Yet there is more to the story because there is less competition in the pile ups. Most of the time I was successfully working the pile ups without turning on the amplifier. I always try that first since it's a bother to turn on and warm up the tubes and the power boost hasn't been necessary except on 160 meters.

Which brings us to the second consequence of the epidemic: apathy. It has been widely reported that despite the additional time we are spending at home many of us are not taking advantage. For hams that means spending less time on the air or on radio projects. There are notable exceptions, like the increased activity in contests. That is good for me since I'm a contester. But these are exceptions and not the rule.

All communications services are subject to the network effect: service usage strongly outpaces the growth of service users. As deployment proceeds, usage growth is geometric. Think of the telephone in its early years. Imagine you're the only person with a phone in town. You have no one to call so you don't use it very much. As more phones are deployed you have more people to call, so you do, and so does everybody else. 

Amateur radio is the same. When many hams exit their shacks, many more follow. The bands sound dead and we lose interest. Bland food isn't tasty; apathy is contagious. The network effect also works in reverse.

The network effect applies to other aspects of the hobby. You don't like digital? What do you do when you have few left to work on other modes? This happened to me on 6 meters with FT8. The network effect is in play with digital, no matter your feelings or mine. I'm even beginning to like it.

No one to talk to with the same interests you have? You move to where the activity is or you lose interest. You might even leave the hobby. As activity for your favourite mode declines the overall decline accelerates so that total silence seems to happen overnight. The transition to FT8 on 6 meters was measure in months, not years. You can call CQ using AM but do not expect a reply except on select frequencies where the remaining aficionados congregate.

Another reason activity declines is due to the same old, same old syndrome. For many, interest is spurred by novelty. DXpeditions spur our interest. The novelty of digital modes is the same. It's akin to spicing our bland foods.

Non-DXers may grow curious and increase their activity when they hear the excitement on the bands over a rare one. Some will jump into the pile ups despite their indifference. The same happens in contests, with non-contesters coming on the band, hearing the activity and jumping in to make a few contacts. Do you hear some peculiar warbles on the band? You download the software and have a look to see what the excitement it's all about.

Excitement breeds excitement. Imagine going for a walk in the quiet of night. You unexpectedly run into a street party with music and dancing and happy people. You stop to watch. Someone grabs your hand and you think, why not, and soon you're dancing, too.

Getting back to DX, maybe it's just my imagination that I am beginning to see more excitement on the bands. The DXpeditions that make an appearance are garnering bigger and more enthusiastic pile ups than they have for many months. 

Perhaps it the rollout of the vaccines that promise an end to the pandemic. People are perking up everywhere, and not only on the ham bands, so it may be more than my overactive imagination. I've seen the renewed excitement with the A25RU operation and others.

Sunspots, vaccines, contests, DXpeditions and more. HF is once again tasting spicy.

Reflections: The Downside of Height

As my antennas get higher I run into novel difficulties. In one sense it's a nice problem to have considering that few hams have antennas that are large or high. Nevertheless it is a problem. In this article I'll review the affect of height on horizontally polarized antennas (primarily yagis) before discussing my own particular challenges and mitigation strategies.

Even for those without this problem the discussion may be of interest and educational. Some of the material is elementary. Antenna height has been covered numerous times in this blog (and countless times elsewhere) and I will reference earlier articles for details that are only touched on lightly in this one.

The antenna does not determine the path

Higher antennas are not always better. More precisely, for an antenna that is already reasonably high, higher is not always better. This is not due to diminishing returns so much as the potential mismatch between the antenna's pattern and what the ionosphere requires for communication.

Put another way, an effective antenna is one in which its most effective direction is the one that nature demands for the intended communication. Nature chooses the direction. Your job is to design and install an antenna that is effective for that direction. The antenna does not determine the path.

Direction is 3-dimensional so we must consider both azimuth and elevation. Good presentations of antenna patterns show both. Let's dispense with azimuth quickly by noting that the correct azimuth is the great circle route (short or long path); that is, except when it isn't! Skew path is not at all rare on the lowest HF bands and on the band closest to the MUF. Smart operators turn their antennas to find the optimum azimuth during difficult conditions.

With that out of the way let's turn to elevation angle. Good DX paths are more common at low elevation angles. There are exceptions; there are always exceptions. An effective vertically polarized antenna with its far field reflections from a high conductivity ground (e.g. seawater) can have an impressively low elevation angle for its main lobe. Most vertical antennas don't do nearly so well. 

Horizontal antennas usually do better over typical ground (medium to poor) when they are high enough. In context, high is with respect to wavelength. On 40 meters and down the height to put the maximum radiation at the required low elevation angle for most DX paths is difficult to impossible for most hams. Hence the prevalence of verticals on 80 and 160 meters. For DXing on these low bands, a moderately efficient vertical typically outperforms a horizontally polarized antenna with the same apex height.

When great height is possible there are dangers lurking. Higher isn't necessarily better. This is a lesson I am learning every day with my complement of low, high and higher antennas.

Modelling height

Software makes it easy to inspect the elevation patterns of antennas at various heights. Consider the following set of patterns for a 5-element yagi at heights from ½λ to 4λ over medium EZNEC ground. Although I am illustrating the effect of height with a 20 meter yagi the pattern is scalable to other bands. 

The elevation pattern scales with wavelength. If you get dizzy thinking about an 84 meter height for a 4λ on 20 meters, you can instead imagine a 2 meter yagi that is merely 8 meters high.

This is a busy plot that may be difficult to read. To help out I'll list a few key points:

• Starting at 1λ there is more than one forward lobe. Their quantity increases as height increases.
• There are deep nulls between those lobes, and that will cause difficulties on the air.
• Maximum gain increases with height due to the concentration of energy at lower angles.
• Low angle radiation increases quite a lot at greater heights. For example, at 5° the gain for the yagi up 2λ is ~6 db better than one up ½λ. Diminishing returns are rapid at greater height.
• By choosing heights that are an integral multiple of ½λ the radiation directly upward is cancelled. I did this deliberately for the plot and it is worth keeping in mind when planning your next tower.

As a general rule, the higher you go the greater the number of elevation lobes and nulls. These can be aggravating since when the signal comes in at an angle where there is a null the antenna will not serve you well. Unfortunately there will always be signals that strike those nulls. It is worth addressing for the contest enthusiast, but also for daily operating enjoyment and DXing.

Many VHF operators may be unaware of the problem since DX paths tend to be at low elevation angles. That is often not the case for sporadic E propagation, as one example. An elevation rotator for satellites and EME can deal with the problem at high elevation angles, where "high" means an elevation angle greater than the half-beam width of the main lobe in free space (see below). 

How those lobes and nulls form

The pattern of any antenna doesn't start at the horizon. All radiate downward. A free space elevation plot makes this evident. At right is one for the yagi discussed above.

The elevation patterns above and below the horizontal axis (0° elevation) are mirror images. When placed over ground the downward radiation is absorbed (dissipated) or reflected upward. 

The half of the radiation that reflects from the ground adds to the direct (skyward) radiation to form an interference pattern by superposition. That interference pattern is the series of lobes (reinforcement) and nulls (cancellation). 

Perfect addition and subtraction requires the amplitude of the ground reflection to be equal to the direct radiation. This is approximately true for horizontal polarization even for poor ground quality. 

When the fields add the radiation in the lobe is boosted by 6 db. Where the phase difference is 180° the null is exactly zero. Of course it's never exactly zero, and over real ground will rarely be deeper than -20 db below the peaks of the adjacent lobes.

At right is the broadside elevation pattern of a simple dipole 4λ above ground. Perfect and poor ground are compared. The effects of ground are easier to see with a dipole than with a yagi.

The first thing to notice is that over poor ground the nulls are not so deep and the lobes not so large. Poor ground absorbs more at high incidence angles so the reflections are weaker. In addition to that, the phase shift will not be 180°. Perfect ground does not have these deficits. The effect of poor ground is modest with respect to filling the nulls, and is negligible at low angles that are of interest to DXers. At low angles even poor ground reflects well.

The second is that the angle between adjacent lobes and nulls is smaller at low angles than at high angles. This is due to the more rapid change in the path length of reflections as the elevation angle decreases. This puts more of those deep nulls at low elevation angles where we don't want them. The higher the antenna the worse the problem.

This review should have been elementary to most hams. It is nevertheless worth recapping the basics before going further.

Terrain

The previous discussion assumes flat terrain, and that is not the case for many. Terrain plays an important role in determining the elevation angles of lobes and nulls, and can be the dominant factor where there are major slopes, hills and other large geographic features.

To solve the terrain problem the usual antenna modelling systems are not helpful. Modelling terrain requires real topographic data and a ray tracing tool like HFTA. I have never used HFTA for my station since the land here is quite flat, with gentle slopes and undulations for many kilometers in all directions. Urban hams also have little to gain from HFTA since although the land may be flat all those buildings and metal infrastructure are near impossible to model.

For those with topography that is not flat and open it is advisable to use HFTA to investigate candidate antenna heights and to calculate the elevation angles of the lobes and nulls. In some cases a low tower will be sufficient to achieve both a low elevation angle and few nulls. For others no tower is high enough. 

One recent correspondent who is working on a 40 meter wire yagi put up the first inverted vee element. It is outperforming his vertical on his most important DX path. The reason is that the land slopes downward in that direction. His experience is typical. It is possible to get an idea of how an antenna in his location will perform in NEC2 by tilting the antenna upward by the same angle as the downward slope (or vice versa for an upward slope) and subtracting that angle from the elevation plot.

Beyond this rudimentary advice I have little to say to those with complex terrain. Use HFTA to find what will work best in your unique circumstance.

Mitigation

You cannot fill an elevation pattern null by aiming above the horizon on any HF band. The ground reflection remains and dominates the far field pattern. For high gain stacked arrays for 2 meters and above tilting can work very well. For these antennas the elevation beam width is narrow and the ground-directed radiation falls off rapidly when the antenna is tilted up. In essence, the ground disappears and the antenna performs as if in free space.

An elevation rotator is routinely used for satellite and EME communication. For low elevation angle terrestrial paths or for low elevation EME and satellite work the ground is as much a factor as it is at HF. At the lowest elevation angles the ground reflections will dominate and cause elevation pattern nulls. Too often those nulls are at inconvenient angles. The only good options are to switch to vertical or circular polarization or to wait a minute or two for the moon or satellite to move.

To fill elevation pattern nulls there are a few common strategies:

• More than one antenna: Having one horizontal and one vertical antenna is perhaps the easiest way to deal with nulls. Switch between antennas and see which is better. The comparison must be longer than a few seconds because of signal fading and Faraday rotation that continuously changes signal polarization.
  
• Stacking: Yagis at different heights are fed in phase, out of phase (BOP) or separately to select the one that works best.
  

Did you notice that the two bullets are related? A stack has more than one antenna, and it is important that they can be individually selected. This is typical for HF stacks since it is so useful for optimizing elevation angle to the path and for avoiding nulls. Yagis in a stack for 2 meters and up are rarely configured to allow selection of one or a subset of them since it isn't as beneficial as at HF.

By feeding the yagis out of phase the nulls and lobes largely reverse. The elevation plot compares BIP and BOP for my stack of 5-element 20 meter yagis. The reversal isn't perfect but it is close. Gain in the BOP lobes provided little if any advantage over selecting the lower yagi alone. BOP was enough additional work for my home brew stack switches that I decided it wasn't worth the bother. Many commercial stack switches have the BOP feature, at a price.

For maximum versatility of elevation angle it is necessary to have at least two antennas, either in a stack or at different heights. One antenna, be it high or low, is a competitive disadvantage for contests and for DXing. I am sure that readers struggling to raise just one antenna per band, or even just one multi-band antenna, are feeling less than sympathetic about my plight! Nevertheless this is what I must deal with to achieve my operating objectives.

By the end of this year I'll have stacks or multiple antennas for 40, 20, 15 and 10 meters. For 80 meters I may reinstall my trusty inverted vee to have a high angle antenna to complement the vertical yagi. It would be useful on some paths, especially when I'm not running low power or QRP. With a kilowatt I can almost always work the nearby stations with the less effective low elevation angle of the vertical array.

On 6 meters I have a problem with just the one yagi. It is up 4λ and has the elevation pattern shown in the plot at the top of this article. Sporadic E and aurora often have optimum paths well above the horizon. That said, the antenna works well for the longest DX paths with that very low main lobe. There are times when friends nearby with lower yagis do better, which is strong evidence that the elevation pattern nulls are putting me at a disadvantage some of the time.

I would like to have at least 2 yagis in a stack for 6 meters. Unfortunately that's not a project for this year. It isn't even obvious where I could put it; the towers are rapidly filling with HF yagis. I need the gain and I need to fill those nulls to aggressively increase my country count on the magic band. I'll come up with a plan next winter in the hope of building a stack in 2022.

Now let's talk about verticals. These include vertical dipoles, monopoles with a radial system and vertically fed loops. When ground mounted or close to ground they have no nulls between 0° and at least 45°. Like horizontal antennas, the main lobe will split and form a null at greater heights. Although there is no critically located null for most verticals there are other difficulties.

First, verticals for the high HF bands are short, and in almost all locations will have to radiate through buildings, utilities, foliage and other common obstructions. This impairs both efficiency and effectiveness. Even with a good radial system a hex beam mounted on the roof of a house will outperform a vertical monopole or dipole, though usually not a full wave loop in its favoured directions. Ground reflections are not as reliably strong as they are for horizontal polarization, and that can cost a few decibels.

The elevation plot at right compares a ¼λ vertical with 8 full-size radials over medium ground versus a hex beam up ½λ. This is an estimate of what to expect from a ¼λ vertical in many urban and suburban situations. I believe it is fair to compare the vertical to a small yagi with gain (directivity) since the installation difficulties are of similar order. Only half the forward lobe difference is due to the yagi's gain. The rest is due to near field and far field ground loss.

On the low bands it is rare for a horizontal antenna to be very high, and that is why verticals are popular for 40, 80 and 160 meters. Unfortunately the vertical is not a good way to fill nulls on those bands since the horizontal antennas are so low they typically have none. Go back and look at the first plot in this article for yagis up ½λ and 1λ. Verticals are used on the low bands since, as inefficient as they often are, they are superior for low elevation angles over horizontal antenna at practical heights.

No magic

If you were expecting me to propose one highly effective antenna with the magical property of having few or no elevation nulls, I am sorry to disappoint. There are no easy solutions. It is no surprise that big gun stations have lots of antennas on each band, since that is the only reliable way to deal with the vagaries of propagation.

The smart operator at a large station will periodically try different antennas and stack combinations. Propagation changes throughout the day and night, and what worked best an hour ago may not be what works best now.

A Contest of My Own

This past weekend was the annual running of the ARRL DX SSB contest. As contests go this is no longer one of my favourites. Also, I don't really enjoy phone contests as much as I once did. It is a DX contest, which I find attractive, but the experience is different for most outside of the US and Canada. For them it's more of a QSO party in which everyone within a limited area work those outside and vice versa. For example, if you're in far away Australia or south Asia the possibilities in this contest are terribly limited. Few bother, and I don't blame them. I would do the same in their position.

I had concerns aside from being busy and wanting to limit my operating time, while still make a good showing. Two of my headsets failed immediately before the contest. That was a difficulty I overcame with an uncomfortable workaround. Another problem was that I wanted to enter a category that the contest sponsor does not support. 

For those reasons and since I had no illusions about winning anything I decided to do it my way. The alternatives -- conforming my operating to categories set by the sponsor, or to sit it out entirely -- were not to my liking. I invented a category that is common in many contests, but not this one. I would not be competitive in the formal categories, and that was okay. 

Contest within a contest

You have an amateur radio license. Provided you operate in accordance with that license your on air activity is yours to determine. When there is a contest underway you choose whether to participate and how to participate and who you work. You are under no obligation to participate in a manner that complies with the requirements of the sponsor's entry categories.

There are interesting examples that are more common than you might realize. For example, to only make contacts with unique multipliers. At the end of a contest your QSO and multiplier totals are equal. There are DXers who enjoy doing this since in global contests like CQ WW there are many contest DXpeditions and widespread interest that brings a lot of DX onto the bands. They have fun and don't care about their score in the actual contest.

Similarly, you might want to work as many stations as possible in just one country, or with call signs that end in the letter "D". Why? Why not! You can do whatever you like. Some clubs or groups of friends agree to a common set of rules and only compete against each other. They have fun and other contest participants benefit from the increased activity. The contest sponsor is uninvolved. It's perfectly legitimate fun.

I chose to enter the 20 meter single band, high power unlimited category -- SO20HP (A) -- in the ARRL DX SSB contest. However, the single band categories are all unassisted. Assistance forces you into the all band category. My reasons for doing it this way included:

• Time: By restricting myself to almost entirely daylight hours I could sleep normally and have time for other activities. At this point in the solar cycle, 20 meters opens around sunrise and closes about 2 hours after sunset. It worked for me since I find that SSB contests are less interesting than CW contests. SSB contests have unique challenges , some of which are listed below.
  
• Limited prospects on 10 and 15 meters: Again, for reasons of propagation, few DX contacts are possible on these bands. After chasing the available multipliers, at a painfully slow rate, there is little left to work.
• 40 meters is a morass: Almost all US activity is squeezed into 75 kHz from 7.125 to 7.200 MHz. There are a few ITU Region 2 stations operating above 7.2 MHz, but nothing in Region 1 or 2. Although Canadians can operate below 7.125 MHz most DX stations focus on that narrow 75 kHz window with the bulk potential contacts. The QRM is overwhelming and QSO potential is low. Some DX stations operate split to compensate. 
• Noise on 80 and 160 meters: SSB modulation has a wide bandwidth and thus a poor SNR. Except under exceptional propagation the rate of DX contacts is slow compared to CW. Staying up all night on the low bands hardly seemed worthwhile when I had no interest in being competitive.
• Station exercise: My best band at the moment is 20 meters. With all the challenges on the other bands I preferred to see what my antennas can do on 20. Despite a few problems with my antennas and antenna flexibility and a vintage amplifier that is not competitive, I believed I could do well. This was an opportunity to find out for sure.
  
• Practice being assisted: My preference is to operate unassisted in most contests. I need more practice being agile when new multipliers are spotted. For example, when during a high rate run of Europeans a needed multiplier in South America or Africa appears it is necessary to move quickly to avoid the inevitable pile up while not compromising the run or losing the run frequency by being absent too long. Just 20 to 30 seconds can be too long.

Those are my reasons and you will have your own to consider before a contest. The point is you can do what you want without feeling constrained by the categories offered by the contest sponsor. Of course if you do intend to be competitive you must fit yourself into a category and maximize your score for that chosen category. The decision is yours and yours alone.

How it went

To be competitive in my invented category I have to compare myself to the single band unassisted participants and to the 20 meter results on the all bands assisted participants. In those comparisons I am still a loser though not by a lot. I'm pretty happy with how I did. There is certainly room for improvement in my skills and the station. 

Propagation was one important factor. I am too far east and north in North America to place highly. A distance of a few hundred kilometers is enough to escape attenuation through the auroral zone. Stations in W2 and W3 had more success working Europe and further afield to Asia and the Pacific. VE1 and W1 have more daylight in common with Europe so that the opening lasts up to 1 hour longer. 

South is also a challenge. W2 and even those further southwest in VE3 often had a better shot to multipliers in the Caribbean and South America. I would get through, eventually, after those with more favourable propagation. I usually do better to the south on 15 meters under poor conditions since closer to the MUF the longer path to my latitude is favoured over those to the south. That isn't the case on 20.

Power is a problem. My vintage amplifier is well below our legal limit, which on SSB is 2250 watts PEP, or triple the 750 watt limit for constant carrier modes like CW. That puts me at a disadvantage that I keenly felt in the fiercer pile ups. I have a new amplifier on order that will fill that deficit.

The TH6 and TH7 tri-band yagis I rely on for most directions on 20 meters do not have the gain of long boom mono-band yagis. The 150' height of the TH7 is wonderful except when competing against those with bigger antenna farms. Due to in-shack control problems I am not able to easily rotate the upper 5-element 15 and 20 meter yagis of my stacks. Until that is properly dealt with they are usually left pointing at Europe.

There are always a maximum number of multipliers available on any band in a contest. Being assisted makes it possible to work all but a few of them. I worked 110 DXCC countries and the biggest guns did perhaps 10% better. In most cases I could not get through the pile ups due to the aforementioned reasons, or I was shy a few decibels to rise above the DX stations local noise.

Working multipliers is not always a hunt. By running on a clear frequency with a big signal most multipliers will find you. You will never work those stations by S & P (search and pounce). At times I was astonished by who called me. One rare multiplier in Africa called me on Sunday after I fruitlessly sat in their pile up the previous day. 

Another time I was startled when I starting being called by stations in southeast Asia with quite strong signals. In the midst of a European run I'd forgotten the band often opens briefly in that direction mid-morning. They weren't running so there was nothing seen on the spotting networks. It was delightful for a DXer like me to have that happen.

Other observations

After the CW version of the ARRL DX contest I used a text editor to extract all the contacts with QRP stations. This can be done easily because power is part of the exchange for non-W/VE. Accuracy is not high because some non-contesters instead send a serial number, their zone or whatever comes to mind. I filtered out those I could and came up with 2.3% of my 2400 contacts were with QRP stations. There were many more using 10 or 20 watts.

This interests me since I am a QRP enthusiast. That's how I returned to the hobby in 2013 and it has remained a passion. That I typically run much higher power nowadays does not diminish my interest in QRP. As a consequence I really enjoy being called by QRP stations in contests. With a big signal I know that I attract those with small antennas, low power or both.

You might expect that QRP would be less common in SSB contests due to the poorer SNR. This seems not to be the case. Although I didn't fully analyze my log the QRP percentage appears to be comparable. My furthest QRP contact was with Japan. That is not easy on 20 meters! I know because I've done only a few times myself when calling Japanese stations with just 5 watts.

Spotting networks are critical to success. Starting a run is slow because many stations click spots and don't tune with the VFO dial. I could monitor this in real time on the Telnet window. Within 30 seconds of seeing my call and frequency spotted the European pile up resumed. I once humourously referred to spots, human or CW skimmer, the QSO faerie.

The downside is that sometimes the spotted call is wrong. When I was spotted as VE2VN on Sunday, when everyone's rate had slowed considerably, I was deluged with dupe callers. For several minutes it was helpful to enunciate my call as Victor Echo 1-2-3 Victor Norway. Until spots aged out on most operators' software the dupe rates remained at 10% or so.

I used the contest to experiment with phonetics in my pre-recorded messages. While running I tried a shorter exchange: "five nine, oh en". This worked very well at first since regular contesters know that VE3 is Ontario (ON). Contest software will helpfully prefill the exchange accordingly. As the rate slowed and there were more casual contesters answering my CQ it caused problems. On Sunday I went back to using "five nine, oscar norway". Problem solved. 

My closing message was "thanks! victor echo three victor norway" and not the shorter "thanks! vee ee three victor norway". When I tried the latter in CQ WW SSB last fall it caused a surprising amount of confusion. This attempt to increase run rates didn't work out. I have always use full phonetics in the S & P message set.

Afterwards

My total operating time was under 17 hours. Had I operated long my score would have been higher. There was no point since my non-categorized entry would win nothing. I don't enjoy endlessly calling CQ or spinning the dial to hear nothing new. When that happens I take a break and find something else to do. I went so far as to take short breaks during the morning openings to Europe. To win it is necessary to practice BIC (butt in chair) and to keep the CQ machine going, no matter the propagation or the rate. Every QSO makes a difference.

There is a rumour that ARRL will expand the categories next year. That may not affect my behaviour since my focus on 20 meters this year might never be repeated. It's more likely that I'll do something completely different. Regardless, it'll be interesting to see what transpires.

I had fun in my own little contest, and that is what matters to me. I'd rather do these long contests as part of a multi-op, and I hope to be ready to do that later this year. It's not just the pandemic causing the delay since I have work to do to prepare the station for it. The work is ongoing. Indeed, that's why there's a long gap between the previous article and this one. I'm keeping busy and the whiff of spring antenna season is in the air.