Multi-band Antennas & Inter-station Inteference

When I first built this station I put up a few multi-band yagis: TH6, TH7, Explorer 14. When operating SO2R in contests I could not share these yagis since I don't use triplexers but I had enough antennas to get by. Over time these antennas have been displaced by mono-band yagis. The last of them, the TH6, is slated for removal later this year.

Trap yagis are inefficient but they can be very convenient for most hams since it is rare to have more than one tower, or one robust enough to support a "Christmas tree" of mono-band yagis for 20, 15 and 10 meters. Let's set that aside in this article to talk about interference between radios -- SO2R and multi-op contesting -- when using multi-band vs mono-band antennas.

Above are multi-band yagis from Optibeam, DX Engineering and Hy-Gain (clockwise from top left). Only the last has traps. However, non-loaded multi-band yagis suffer various gain and bandwidth deficits in comparison to mono-band, full-size yagis. Coupling among close spaced elements, even if each element is resonant on a single band, create many anomalies. The same is true for mono-band yagis placed too close together. 

In general, multi-band antennas are often high-Q, with narrow operating bandwidth, due to traps and other devices to enable resonance on more than a single band. Simple antennas without those devices can also be multi-band by exploiting harmonic behaviour. These include full-wave loops (resonant on all harmonics), dipoles (resonant on odd harmonics), and EFHW (end fed half wave) multi-band antennas that are popular with many hams that lack towers. 

Multi-element mono-band directive antennas like yagis may resonate on harmonics but they will not be yagis at those frequencies. Therefore they are potential interaction sources while not being useful at those higher bands. For example, a 40 meter yagi on 15 meters can behave as a resonant long dipole with a complex but largely non-directional pattern. It can seriously degrade the pattern of a 15 meter yagi quite far away, depending on their positioning; reciprocally, the 40 meter yagi will induce significant current from a 15 meter yagi and send it down the transmission line to the receiver.

This brings us to BPF (band pass filters). They are the almost universal choice for managing interference between radios in a contest or DXpedition operation with two or more stations. For the present I'll focus on the most common situation of one station per band and not on the more difficult one where there are in-band stations.

BPF are not a universal solution since there are things they can't do. Our primary concern is reception, where we want the BPF in the transmission and reception paths to minimize interference and performance degradation. It is important for the station designer to understand how BPF function to determine how they can be best deployed. For stations with high power amplifiers the interference can be far worse. In this case the placement of BPF between the rig and amp or between the amp and antennas can have substantially different outcomes.

Other station elements impact inter-station interference, either by enhancing the effects of BPF or rendering them ineffective. For example, poor port isolation in an N×M antenna switch. BPF are critical but are not by themselves sufficient to eliminate interference.

It must also be noted that BPF are not always necessary. I operated SO2R very successfully at QRP power levels. When the antennas don't strongly couple modern receivers typically won't overload from the 5 watt fundamental on a different band. You just need to select operating frequencies to avoid harmonics from the other transmitter. If the antennas are far apart you can even do SO2R with 100 watts, and I have done so. In both cases you must also avoid transceivers that generate unacceptably high broadband noise; there are a few notorious examples that I won't mention here.

For the rest of this discussion let's assume a station that requires BPF for acceptable performance. As noted, BPF are just one element of station design. Now consider the following case of a tri-band yagi.

In this example the receiving radio is on 10 meters while the other station transmits on 20 meters on a different antenna. Even if the transmitter BPF cuts the 2nd harmonic by 70 db it can't be entirely eliminated. It can still be an overwhelmingly strong signal on 28.024 MHz that may require the 10 meter operator to QSY. If the 20 meter amplifier has poor harmonic suppression and the BPF is between the rig and amp (low power BPF), the interference can be worse.

On the other hand, with appropriate protections it is possible to share a tri-band yagi, and to do so without destruction degradation of receiver performance. There are several manufacturers of triplexers and associated high power BPF that make this possible, but it can be very expensive. Yet it may be cheaper than another tower and yagi suitably placed and filtered. 

The diagram is from VA6AM's web site where he presents numerous options for antenna sharing and what can be expected with respect to performance. I know sharing can work since I've operated at stations with this setup. One cautionary note: don't try this with trapped tri-banders and high power! The traps are unlikely to survive 2 to 5 kW of combined power from up to 3 transmitters.

Returning to the previous example, the 10 meter station's antenna contributes to the problem. The tri-band yagi is resonant on 10 meters and will take that harmonic and deliver it to the amplifier. It will pass through the amp unattenuated (on receive) and be attenuated by the BPF. It would seem that disaster has been averted, but has it? There is more to the story.

The annotated Google satellite view of my station shows the south pointing TH6 in relation to the high band stacks, the 40 meter antennas and the Skyhawk tri-band yagi. Let's say the TH6 is used by the 10 meter station in our example and the other station uses the 20 meter stack pointing to Europe (northeast).

As already shown, the 20 meter station's 10 meter harmonic is loud but is otherwise not a serious problem. It is usually sufficient for the 10 meter op to QSY 5 to 10 kHz on CW -- more separation is needed on SSB due to the wider signal (~6 kHz for a clean signal on the 2nd harmonic). Despite the actions of the two stations' BPF, during last year's CQ WW SSB our team discovered a serious interaction that I had not anticipated or previously experienced.

The 10 meter amplifier tripped and went offline. The problem wasn't the harmonic, it was the fundamental 20 meter signal that did it. The full kilowatt on 20 meters on the stack pointing at the TH6 was unattenuated by the yagi since it is resonant on 20 meters. The 10 meter station's BPF, which in my case are low power BPF between the rig and amplifier, protect the receiver but not the amplifier.

Still surprised? Here is what happened. Quite a lot of power appeared at the 10 meter station amp's antenna port. It is clearly visible on the amp's power meter which, like many modern amps, measures power whether the amp is in transmit or receive (bypass). There were several 10s of watts displayed on the amp's power meter. 

In this instance the amp was an Acom 1200S. The amp's protection circuits saw this as unexpected power output during receive. It was interpretted as an amp fault, such as oscillation while in receive (standby). The protection circuit flags this when there is no corresponding RF power on the input (transceiver) port. It's a sensible precaution despite the aggravation it caused us.

Had there been a high power BPF on the antenna side of the amplifier the problem would not have occurred since it would block the 20 meter fundamental signal picked up by the tri-band yagi. Our options were to switch to a 10 meter mono-band antenna -- which passively rejects 20 meter energy -- or turn the Skyhawk tri-bander south and hope that it was far enough out of the 20 meter stack's main beam not to pose a problem for the amp. Fortunately both options worked, but it was inconvenient for the operator to deal with.

I've previously discussed why I chose low power as opposed to high power BPF for my station, so I won't repeat that here. With that as a given, my task is to minimize interactions using some combination of BPF, stubs and antennas. Stubs can greatly attenuate harmonics produced by amplifiers if that is a problem; low power BPF filter the transmitter's harmonics. 

Solid state amps are more likely to generate harmonics than tube amps. Hams tend to run amps hard and that can markedly reduce linearity. Tube amps are better at harmonic suppression when that happens since the output impedance matching network (usually Π or T) also serves as a low pass filters. The output transformers typically used in a solid state amp don't have that feature.

Since my objective is to have solid state amps on both operating positions in my station -- for contesting agility and guest operator convenience -- it is worthwhile to invest in amps that have enough headroom with respect to our legal limit so that they are less likely to be operated beyond their linear range. The 1200S may have to be replaced.

There is more that I can do with antennas to reduce interaction. As already noted, even a dipole is resonant on odd multiples. That also applies to mono-band yagis that are made with dipole elements. They will pick up substantial harmonic energy from other antennas even though they are not exactly resonant on the harmonics.

One good example in my station is the 3-element 40 meter yagi. Through extensive modelling I discovered that the pattern of the 15 meter stack could be severely distorted when point at the 40 meter yagi, which is on the popular European path. I used small capacitance hats to move the 3rd harmonic well outside the 15 meter band to solve that problem. A side effect is that the 15 meter fundamental signal from the stack is greatly attenuated in the direction of the 40 meter receiver when using the big yagi.

The reversible Moxon on the same tower is naturally non-resonant on 15 meters since the topology of Moxon elements incorporates capacitance hats. It is also true to a lesser degree for the more conventional Moxon rectangle. The XM240 and similar inductively shortened 40 meter yagis are the same. The only difference in this respect is that inductive loading lowers the 3rd harmonic resonant frequency while capacitive loading raises it. 

The XM240 works pretty well on 17 meters and the 3-element 40 meter yagi works well on 12 meters. Since I have no resonant antennas for 17 and 12 meters the designs of those loaded 40 meter yagis had an accidental benefit for operating on those bands.

Even the 30 meter delta loop shown at left has interesting interactions that prevent its resonance on 15 and 10 meters, which are close to the 2nd and 3rd harmonics. In the EZNEC plot above, the currents are for the delta loop excited at 28.5 MHz. There are two effects that are worth attention.

First, the location of currents can be quite complex at harmonic frequencies. In this case there is very strong coupling to the tower; it is less at 21 MHz but still quite large. For the interaction case we are more interested in the feed point impedance than the pattern. The SWR is very high on both of these higher bands. At 21 MHZ the impedance is around 210-170j Ω and 2+20j Ω at 28.5 MHz. 

Part of the effect is due to tower coupling but also the 75 Ω ¼λ transformer (cut for the 30 meter band). The transformer is approximately ½λ at 21 MHz and ¾λ at 28.5 MHz. Although in the last case it is approximately a ¼λ transformer, the loop's feed point resistance can be quite different on it harmonics. This is an excellent example of how a matching network can beneficially filter unwanted energy from other antennas.

This is only bad news if your intent is to use this antenna on other bands. I am not. It's potentially good news for antennas with "interesting" matching networks. Matching networks, other than transformers, are narrow band, typically working on just one band or a portion of a band. 

Antennas that are resonant on harmonic bands typically will strongly reject the fundamental signal since the feed point impedance, due to the antenna being quite short on the fundamental frequency, and the feed point matching network (gamma, beta, etc.) presents a large mismatch to the signal on a different band. For example, a 10 meter yagi with a beta match presents a high SWR to a received 20 meter signal. Checking the impedance on other bands of a few mono-band yagi models in my files confirms this.

While inconvenient, you can test what you have by making and testing a model of the antennas on other bands. Or you can climb the tower and measure the feed point impedance on those bands. A high SWR in this case is desirable because the antenna is unusable on those bands. This is exactly what you want for contesting. The time spent can be especially beneficial before an antenna is bought or built.

To conclude this long article, I'll give my thoughts with respect to my own station:

• No triplexers or high power BPF: It's expensive, but so is another tower and antenna. While not ideal, I will make do with more modest objectives for contesting using low power BPF. The TH6 is being replaced since, due to its placement, there is no good way to effectively decouple it from the 15 meter stack. Its replacement will be 20 meter mono-band yagi, and possibly 15 and 10 meter mono-band yagis on a different tower. Harmonic pickup will thus be strongly attenuated. The Skyhawk is far enough out of the stacks' lines of fire (west of the big towers) that it doesn't suffer the same ills.
• Stubs: I've been planning to experiment with coax stubs to better deal with amplifier harmonics (I use low power BPF) but haven't gotten around to it yet. That may be enough to solve the few remaining interaction issues I experience, especially on CW where you often find yourself on the other station's harmonic. These must be switched and installed at both stations' amplifiers. 
• Transceivers with high blocking and mixing dynamic range: Direct sampling receivers like on my Icom 7610 are susceptible to overload that can be somewhat ameliorated with its internal filtering option. Superhet designs are still typically more resilient than direct sampling receivers. The advantage is gradually diminishing as SDR technology evolves.
• Situational awareness: Understand the potential for interference from the other station and each station's antenna choice, then avoid those situations. You might think this is easier when operating SO2R than in multi-ops since I know the station well and control all choices, but it's really easy to make mistakes in the heat of high rates and frequent band and antenna changes. There's a lot to keep track of. 
• Polarity: Antennas with opposite polarity interact far less than those with the same polarity. It is for this reason that multi-ops will use verticals for their in-band stations. I haven't done this yet in my station but I may yet do so if I get more serious about hosting multi-op teams. Keep in mind that the often quoted 20 to 30 db of polarization attenuation is an exaggeration. Relative positioning, induction in various structures and squint angle can reduce attenuation to 10 db or less. 

Decades ago I did many multi-op contests using kilowatt class amps without BPF or stubs and we somehow survived. The receivers didn't always survive so we kept spares on hand. Repairs weren't difficult with those simpler rigs, often no more than replacing a neon lamp: the so-called lamp fuse. Mostly we just argued about who should QSY when inter-station interference became a problem.

No matter your contesting objectives, hopefully there are a few useful ideas in this article. There is a wealth of data out there if you want to do a deep dive into the topic.

Springtime Lull

The bad spring weather continues. This has been the wettest early spring I can remember for perhaps 10 years. At least it has warmed up, although we still have regular cold weather. That isn't so bad except that it comes with high winds and snow. It is always amusing to see the tulip shoots pushing up through the snow cover. This weekend it was a summery 25° C on Saturday and snowing on Sunday.

About the only productive work I've done outdoors was several hours clearing brush along the Beverage lines in preparation for summer growth, and to take down several large dead maples that threatened the towers or buildings. Felling trees isn't so hard but cutting them up and disposing of the debris is a lot of work. I also spent time putting connectors on and testing Heliax runs that I hope to bury in a trench to one of the big towers either this spring or in the fall.

I did manage one tower climb to resume work on one of my projects. That was great until I fired up the station for the Ontario QSO Party and found out I had trouble with both prop pitch motor rotators. One wouldn't turn at all and the other had an intermittent direction pot.

Remember this uncomfortable truth with large stations: you can be as thorough as you like yet there are so many things that will go wrong. Maintenance is never ending, no matter how well you build it.

I've had time to operate yet admit to doing little. General chatting doesn't often interest me and there has been little happening on-air to attract me. I've been passively monitoring far more than I've operated.

• There are no interesting rare DXpeditions at present. 3Y0K brought excitement for a while and then there were S21ZD and XX9W, plus a few others that drew my attention. The latter were difficult due to being shots over the north pole. They seemed to have more luck with Europe and with FT8 so that's what they did. 
• Despite that difficulty, with daylight shining on the Arctic there have been regular openings most evenings to Asia over the pole, at least on 20 meters, and some on 17. The several days long dive of the solar flux below 100 bodes ill for 15 and 10 meters. The years long slide down to the solar minimum is well underway.
• 
  6 meters briefly showed signs of life around the spring equinox, as expected. I heard South American stations almost daily for nearly 3 weeks. That dried up in early April. In any case there were no new ones to work. There was a CE0Y station active but not on 6. It will be several weeks yet until we see the first glimmerings of the summer sporadic E season.
• 160 meters has been quite poor. Most evenings the Europeans are very weak. Even the FT8 activity is subdued. There has been little DX at our sunrise openings, just the occasional VK and KL7, with just one JA heard on FT8. I expect better with the quiet geomagnetic conditions at present. As previously mentioned I heard but did not work 3Y0K on top band. I could have tried harder but it was inconvenient. Soon I'll be rolling up the radials for the duration of the farming season.
• There are no major contests. The next is WPX CW in late May, which I may enter for practice since it's not one that I particularly like. The only QSO parties that interest me are the Ontario QSO Party, where I want to raises the activity level, and perhaps the Florida QSO Party since it is one with lots of activity. Handing out a mult was fun in OQP but the contest was otherwise not terribly exciting.

While the rain pours and the winds howl, keeping me off the towers, I am dabbling with various indoor projects. 

• 
  I made significant strides on the software for the next version of my antenna selection software. Although it won't be ready for a while yet I am getting close to connecting the new UI (user interface) to the Arduino-based antenna switching system. The design process has been interesting since the revised UI requires a different relationship between clients and server. I may write about it when the project is done.
• To support the antennas slated for construction this year and next I am preparing Heliax runs to the tower that hosts the 20 and 15 meter stacks. That tower also has a 30 meter delta loop and the tower itself is shunt-fed for 160 meters. A new trench will be required, running parallel to the one I dug 6 years ago. I'll toss a Cat5 cable into the trench for control line expansion.
• Most of the material for the new 3-element 20 meter yagi has been assembled. I'm thankful that the aluminum is on hand because, have you see the price of aluminum recently? Antenna prices are going up, commercial or home brew. It ain't easy being a big gun!

This article took me so long to finish that I finally did spend a few hours on the towers. Many more will follow as the spring weather stabilizes. I'm beginning to realize how much work there is to do this year. I'm getting exhausted thinking about it. The springtime lull won't last much longer. Then, if I feel lazy, I'll have different excuses to avoid work on the station, such as ticks and the growing hay.

Stray Capacitance in Interaction Models

Measuring stray reactance -- L and C -- can be difficult because the values are typically quite small. Yet that is a requirement I've dealt with when modelling antenna interactions. Test fixtures can only be built with some difficulty and then measured with suitable instruments, and I've never done that before. The literature addresses some of the cases I run into but not all. Then there's the matter of whether the quoted figures are reliable since the measurements methodology may not be described.

There are two cases in particular that I want to discuss since they are prevalent in my station and I've harboured doubts about my methods and calculations:

• Coupling of guy cable segments at insulators. There is coupling due to field interactions (naturally dealt with in NEC engines) and the series capacitance of the overlapping guy grips.
• Coax common mode leakage across transformers with galvanically isolated windings. I use lots of these in my Beverage systems, and I use more in long runs of RG6 lying on the ground that may be parallel to Beverage antennas for some distance. 

When I first developed interaction models in EZNEC for my guyed towers I modelled a wire for each non-resonant guy segment and overlapped by a length and separation approximately that of what was built. That was cumbersome and not really very accurate, but probably good enough. For the small Beverage transformers I represented the coax with connected wires and placed series capacitive loads on the wire to model the series capacitance between the transformer windings. I used values gleaned from ON4UN's Low-Band DXing and other sources.

The latter method of modelling stray capacitance is easier than the former, so I've been using it almost exclusively for the past several years. However, I don't know how accurate either method is or can be.

It struck me as an ideal small project to tackle during the extraordinary and persistently bad weather we're going through this April: rain, snow, wind, cold. There are always jobs to do in the shack and the workshop when tower work is too uncomfortable. I set out to measure the series capacitance in the cases listed above with the hope of designing better interaction models in the future.

I have a 1:1 Beverage transformer on a BN73-202 binocular ferrite core with 3 turns of insulated #26 wire for both windings. It was left over from a project and is identical to what I use for isolating coax segments in my long RG6 runs to the Beverage antennas. For the other case, I quickly constructed a "dummy" guy segment termination from a 504 insulator and two 5/16" guy grips. This is what I use on my big towers supporting stacked yagis and large 40 meter antennas.

There are 3 instruments that I have available for the measurements:

• RigExpert AA54 antenna impedance analyzer (single port)
• VNWA3 2-port VNA
• 35 year old LCR meter (made in Taiwan, and the brand is defunct)

I first did the measurements with the AA54. The results, at first, seemed sensible, but did not pass scrutiny. This shouldn't have been a surprise since these analyzers, even one of this quality, have increasingly poor accuracy as you move farther from its 50 Ω reference point. A pure capacitance in series with an infinite resistance (open circuit) has a very high SWR indeed. It is a poor LCR meter in these circumstances.

You may have to click on the image to improve the resolution. On the right are two measurements of the transformer, one open and one with the transformer in circuit. The ends of each winding are joined for the measurement of inter-winding capacitance. I compared the two calculated capacitance values with the expectation that their difference would be close to the actual value. In this instance, the difference fell between 2 and 3 pf: measurement precision is no better than 1 pf.

Notice that the R value is 0 Ω for all of the measurements. That casts suspicion on the results. The open circuit is so out of bounds from what this single port device can accurately measure that some deviation was to be expected. The measurement of the guy cable series capacitance is about the same, further casting doubt on the suitability of the instrument for this application.

I tried the measurement from 1 to 50 MHz in the hope that there would be an island of stability, if not accuracy, at least at low frequencies. At low frequencies the calculated capacitance was far too high, only stabilizing above about 5 MHz. So I chose 50 MHz and got the same result at a few other randomly selected frequencies. The poor accuracy really isn't the fault of the antenna analyzer. I asked it to do a job it was not designed for. 

I moved on to my old and trusty LCR meter. Like most of these instruments it does its measurements at a low frequency, although that is not documented. But I have had a lot of success with it over the many years I've owned it, measuring fixed and variable capacitors from a few pf up to a large fraction of a μF. A major downside of the meter is that it eats through 9 volt batteries very quickly.

The LCR measurements were quickly done with the aid of the short alligator clip leads. The stray capacitance of the instrument plus leads is slightly below 6 pf, so we subtract that from the measurements.

The results are far more in line with my expectations: 5.6 pf for the transformer and 11.3 pf for the guy termination. The Xc at low HF frequencies is close to what others have measured for a transformer of this design. That gives me confidence that these values improve my interaction models. Greater measurement accuracy may be desirable for capacitors used in antennas and matching networks.

I did not do measurements with the VNWA 3 at this time. With the many recent PC upgrades I made this winter it would take some time to set up the software to use it. The single port (S11) measurement would likely be better than with the AA54 but probably not by a lot. More accuracy requires a 2-port (S21) measurement of the series reactance, using a fixture that includes the outer coax conductor. Maybe when I have nothing better to do at a future date I'll make the measurements if only to satisfy my curiosity.

In practice there are many parameters that determine guy wire interactions, with the series capacitance just one of them. As you go higher in frequency the Xc falls enough that there is significant conductance through those guy terminations. For example, Xc of an 11 pf capacitor 30 MHz is just 480 Ω. It's 10 higher on 80 meters. Those non-resonant guy sections are not as isolated as they appear! Don't be surprised if they model differently than you expect when you include the stray capacitance between supposedly non-resonant guy segment.

There are also induced currents from the antenna itself and among the guy segments despite each segment being non-resonant in isolation. Perfection isn't possible: we can only do the best we can. I intend to use the LCR meter measurements in my EZNEC interaction models until I have better.

Is it worth the effort? I believe so. I've put enough years and sweat into my "big gun" station that it is only sensible to get the most from it. That doesn't mean I'll make major changes when an interaction is worse than I'd like, but I'll know what to expect. That's valuable information even if it isn't good news.

Ignorance is not bliss. 

Did FT8 Save Amateur Radio?

It was with some surprise that an article I wrote a few months ago went "viral". Well, viral as far as it can be within a limited population of hams. It has been the most popularly viewed article in the recent history of this blog. 

Digital modes court a range of emotional responses from hams that have been licensed for a long time. Newer hams just shrug and carry on. Digital is undeniably popular. Many of the public comments and private feedback to my article seem to have missed the point. I was drawing attention to the way the world is, not the way any of us might wish it to be. So, yes, digital has won. You don't have to like it.

At the risk of being seen as taking advantage of the controversy I will revisit it for a particular reason. It isn't for the financial reward since I get none from the blog. That reason comes from a throwaway comment made by a friend when we spoke recently. That's the source for the title of this article. We laughed it off, but I kept coming back to the question over the following days. 

It's worthwhile to flesh out the arguments pro and con. I might as well since I am unable to get any tower work done due to weeks of poor weather. The above photo was taken this morning. I envy those of you that don't experience spring snowstorms. Warm weather is on the way so technical articles will follow as I start into my long list of tower and antenna projects.

First, what if there were no FT8? What would have been the implications on licensee numbers and on-air activity? There is no way to know for certain. Instead we have to look at the evidence that exists, circumstantial though it may be.

Let's review a few facts, not all of which have hard data attached. I am not willing to invest the time to do extensive research for a brief article like this. Hopefully there are no significant errors:

• There are more hams in the world than ever before. It is certainly higher in Canada, the US and many Asian countries other than Japan, growing at rates faster than the total population. It may also be true in Europe, though not so much elsewhere.
• Towers for effective HF communication are being eschewed by new and young hams in developed countries for a variety of personal and societal reasons. That was not true decades ago. They prefer simple antennas, portable operation (e.g. POTA) or may avoid HF entirely.
• Few new licensees know CW and only a fraction of them learn or are planning learn. Yet phone and conversational digital modes can be difficult for those with small stations. Like long time hams, there is more interest in making contacts, DX or otherwise, than having conversations. Conversations take place off-air, even among hams.
• VHF/UHF FM is the gateway for many new hams, for local communication, public service and emergency preparedness. Many of them let their licenses lapse. A few of those that stay migrate to HF. 

It is a commonly held belief by many older hams that if there were no digital modes that new hams would be active on (what they like to call) "human modes." That is, where a computer is not an active component of the QSO. This mainly is meant to mean CW and SSB, although some will include RTTY and other computer encoded/decoded modes that permit conversations or data communication.

Is that true? We can only speculate since there is no way to do an experiment. Take a look at the waterfall spectrograms shown in that earlier article that caused such a fuss. Do you believe all those FT8 signals would transfer to CW and SSB if we auto-magically and retrospectively eliminate digital? In my frank opinion, no, that would not have happened.

There are few conversations taking place on HF. Most are "599" DX QSOs or POTA activations. Those that are actual conversations are between hams of long acquaintance who have a regular schedule or participate in so-called nets. If we restrict our focus to CW there are even fewer conversations, and those are typically not between or with new and young hams.

CW won't die but it will become a niche mode. SSB will continue since it is easy. Few new hams that are solely on FM will stick around, or will find their niche there and stay there.

Digital modes, FT8 in particular, are undeniably popular. New hams with small stations can work a lot of DX on HF, and they do! They really enjoy it and have been bitten hard by the DXing bug despite the naysayers. It doesn't interest me as a contesting mode though some promote it as such.

That said, is there an attraction for a digital-exclusive HF operator to spend more time on SSB and to learn CW? The answer is yes. Many are learning CW to improve their POTA results, mix it up in the pile ups and to become more versatile contesters. It has been said (and I agree) that CW is an ideal contesting mode.

Of course, many of those using digital on HF are unlikely to ever learn CW and they are discouraged by attempts to DX with SSB from their small stations. We are well below replacement numbers on CW, so its use will decline as elderly hams depart. It has had a wonderful 100 year run but now its time has passed. SSB will continue as a DX and contest mode and for some conversation. FT8 will likely be a mainstay for general operating and DXing on HF for many years to come. However, we can't reliably predict far into the future. Time will tell.

I've droned on for longer than I intended. But it's relevant to the original question: did FT8 save amateur radio?

If we restrict ourselves to HF, I am leaning towards yes. I'm not convinced but I am persuaded. Had there been no FT8 (by far the most popular digital mode on HF and VHF) those hams currently active on FT8 would not be on CW or SSB. The spectrogram of a CW band segment like that in the earlier article would likely look very similar.

That's not the end of the story since FT8 does more than just increase activity at 7074, 14074 and the other FT8 watering holes. Once these hams get hooked on HF, DX or POTA, their ambitions grow. Many hams new to CW and SSB have migrated after being almost exclusively on FT8. SSB first, of course, yet many are learning CW. Why? What incentive do they see?

The answers are various, with no one overriding reason. The following are ones I've personally heard from newer no-code hams. Keep in mind that these observations do not comprise a statistically valid sample:

• The challenge of learning and becoming proficient at the code
• Improve results in radiosport activities: POTA, SOTA, DXCC and contests
• The high rate potential in competitive contesting
• Relatively simple home brew CW equipment for the technically oriented

Communication isn't in the list since that isn't the attraction in 2026. It seems to only attract a minority of new hams. Again, it isn't about what ought to happen (however you may feel about it) but what is happening.

There is a story in the current (April-May 2026) issue of the National Contest Journal about one relatively young ham, WM6Y, who took the CW challenge after spending time on FT8. You have to be an ARRL member to read the article so I will quote a few sentences:

"Do not dismiss digital modes. They can be a gateway, not a replacement. Sometimes the path to CW does not start with a key. Sometimes it starts with a computer screen — it did for me. FT8 brought me back to amateur radio. It motivated me to upgrade my license. It led me to portable operations and ultimately to CW. Without FT8, I might never have returned to the hobby at all."

In his case the activities were POTA and contesting. That agrees with my experience talking to newer hams, as I mentioned above.

Digital isn't so bad, so cheer up. These modes can contribute a great deal to the future health of the hobby, whether or not hams decide to later migrate to CW and SSB. I regularly use FT8 on 6 meters and a few other cases, despite initial reticence. I guess you could say I took the opposite migration path: from CW to digital. 

The future is potentially bright for our beloved hobby, and digital may be an important reason why.

CQ WPX SSB 2026

I did not operate the WPX SSB contest. I don't particularly like it and I said why in an article many years ago. There is no reason to repeat any of that here, so read that article if you want to know why. Indeed, I've provided other reasons in articles before and since. Search the blog if you are interested. This is not to say it's a bad or problematic contest! This is about my personal preferences; many of my acquaintances feel the same.

I was therefore happy to make my station available for another contester to operate the WPX SSB contest this weekend. Shel VA3AA took up the challenge. He's operated here a couple of times before, most recently in ARRL DX SSB. This was a learning opportunity for him, to put in a lengthy 36 hour effort and make tactical decisions as a single op rather than as part of a multi-op team.

Conditions were reasonably good. His raw score was a very respectable 7.5M, including more than 2400 contacts and just shy of 1000 prefixes. There were times he was frustrated and times when things went wrong. Yet in the end he left Sunday evening with a big grin on his face. He is certain to do better in future contests. Contesting is a skill that can take years to perfect.

I made myself available for the entire weekend to resolve station problems and to help him make the best use of the station. Having many antenna choices is both a blessing and a curse: there is a lot to deal with. From time to time we discussed operating tactics and techniques. Those of us who have been in the game for a long time often don't realize how much there is to learn before we become proficient contesters.

Big stations run a lot in this contest, especially in the early hours. The reason is that there is little need to chase multipliers when almost everyone is a multiplier. But if everyone runs there is no one to work. It can be a good strategy to hunt stations at first rather than run since the rate can be better. Soon, though, you have to run if you're to do well. Happily that is effective with a big station like mine. Stations running low power or QRP have a more difficult time in WPX than in many other major contests.

Despite its importance, getting too comfortable with running can work against you. It is vital to frequently switch between running and hunting to maximize rate and multipliers. When the run rate isn't what it should be, switch bands or make use of the second radio to hunt stations. With SO2R capability it is generally advisable to always run on one radio and hunt on the other. For the proficient, there is 2BSIQ. In WPX, hunting on the second radio is usually the better strategy for most competitors.

SSB SO2R is more challenging than for CW or RTTY. Call signs at the very least must be voiced. For a variable exchange (serial numbers in WPX) the challenge is greater. At the very least it is important to use voice messages (CQ, Thanks, call sign, repeat please, alternative call sign phonetics, etc.) to save the voice, avoid unnecessary improvisation and leave your voice free to speak on the second radio. 

TTS (text to speech) and related voicing technologies are increasingly being used to make SO2R and 2BSIQ almost as easy as on CW or RTTY. It is in its early phases and implementation is not yet easy. It is already available as a feature in N1MM Logger+. Not everyone approves of the new technologies, but don't let that dissuade you. It will become routine and universal before long.

I have never seriously operated SO2R in phone contests. I have the basic capability but it was mostly untested. It took some effort to configure the station to switch message playback and microphone to the appropriate radio. Foot switches for each radio are useful, or VOX can be used, however these only work if the software switches transmit focus accordingly. Operator action is required to ensure the routing of the mic is correct. 

I am mostly familiar with N1MM, and it does phone SO2R pretty well once you climb the learning curve. It's a skill that competitive contesters need to learn. I did the setup but Shel had to practice doing it effectively. Now that it's working I'll probably use it more myself.

Agility is critical in any contest operation, and can be especially important in WPX. You have to run but when it doesn't deliver results you have change something. The station must enable agility so that the operator is not inhibited. For example, having to tune amplifiers on band changes, large frequency excursions (e.g. clicking on a spot) and changing antennas, discourages the operator from adjusting tactics on the fly. Although it may not take long it is a burden when every second counts. 

I am planning to acquire a second solid state broadband amp this year and to increase the availability of antennas with low SWR across the bands of interest. This will be a busy year if I'm to be ready by the fall contest season. There is also the rewrite of my antenna selection software (user interface only) to improve the visibility of available antennas, their selection and direction control for rotatable yagis and steerable fixed arrays. That project is ongoing but unlikely to be completed for several months.

There were technical issues, as is typical for a large station with so many potential points of failure:

• We courted disaster a couple of times because my home brew prop pitch motor controller doesn't check for over-rotation. I put off development of that feature until a future version, which may have been a mistake. Operators (including myself) are almost certain to forget whether, when pointed south, it got there in the clockwise or counter-clockwise direction.
• The Icom 7600 is known to have a power spike when the transmission begins. It doesn't happen often and it is notoriously difficult to measure. The Acom 1200S protection tripped numerous times during the contest. The only solution is to replace the transceiver. I may do so this year for this and other reasons.
• The TH6 is tuned for CW and therefore has a moderately high SWR at the upper ends of 20, 15 and 10 meters. That made the antenna almost unusable. Plans to replace the antenna (which is fixed south) are proceeding.
• The 40 meter reversible Moxon does not function in the reverse (south) direction. That made it difficult to work as many US stations as are necessary in this contest. Wintery weather has made repair impossible. I hope to get it done in April. Nevertheless, Shel found that it worked quite well since the F/B is fairly poor above 7200 kHz.
• SO2R Mini switching of the mic input occasionally misfired. It could be fixed with a software reset but that cost time. It's time to upgrade the firmware and hope that solves the problem. Having not done mic switching before I was unaware of these issues before Shel encountered them.

Back to the contest, Shel found that it was difficult to choose off times and focus geographies based on activity levels. Single ops only get to operate 36 out of the 48 hours, making the choice of off times very important. The same is true when operating in the Classic overlay category (24 out of 48 hours). Make the wrong choices and your score will suffer -- don't prioritize personal comfort over operating schedule if your objective is a high score.

Conditions were pretty good for the contest duration, or at least consistent and predictable. We are late enough in the season that 10 meters was poor on the important NA to Europe path, and 15 was poor the second day. The noise level on 80 meters was higher now that spring weather has arrived. 40 meters was, as usual, a zoo on the SSB segment. Running meant staying below 7125 kHz for DX and above 7200 for the US to avoid the din between 7125 and 7200 kHz. Of course many Americans called when Shel was outside the US phone band and Europeans called when he operated above 7200 kHz. Too many operators do not pay attention when chasing spots.

When DX conditions are poor we have the large population of the US nearby. That is not as useful as in years past since contest activity in North America has declined. The decline, while not large on phone, has a noticable impact on scores. There are records established years ago that may never be beat. Setting those as an objective can lead to disappointment. Whether propagation or activity, a contester must adjust his or her tactics to deal with what we have to work with.

After so much negativity I should admit that I'm tempted to enter WPX CW in late May. If nothing else it will be an opportunity to practice my SO2R skills. I typically don't care for contests in the warmer weather so this exception might not happen if the weather is particularly fine that weekend. 

Wall Decorations

Over the decades my shack walls have always been bare. The one exception was when I was a new ham (1970s!). At that time I pinned a few treasured QSL cards on a corkboard in the basement shack of my parents' house. None of my many shacks since have had any such adornment. 

I never framed my license, contest achievement awards or anything else. QSLs lie forgotten in boxes, certificates discarded or filed away and plaques stacked on bookshelves. I have never applied for DXCC or any other operating awards so I don't have those either. About a decade after graduating from university I finally framed my science degrees yet never hung them up. Plaques, paper certificates and educational accomplishments never leave their storage boxes. The same was true of family pictures until recently. 

I am not one for public displays, particularly those regarding personal accomplishments. It looks too much like bragging, a behaviour I hate to see in anyone. Plaques on walls don't have to be about bragging but may be. Everyone has their reasons.

In my dotage I have relented to a degree. Family portraits and even an original painting now adorn the walls of my house. There is some comfort in that since I've lost so many family members. Yet until recently the shack walls continued to be bare. That changed earlier this month.

It isn't an impressive array of contest plaques compared to some others. It is just what I have, or at least all that I've found. There may be plaques from contests much early in my contesting career but I honestly can't remember. If they exist they are buried deep. I feel no great urge to dig through dozens of boxes that I haven't opened for many long years.

Since I've never done this before and it isn't intended to be a brag wall, there has to be another reason. It's a simple one really. When I organize multi-op contest efforts and invite younger contesters to participate the plaques might provide inspiration. For seasoned and new contesters alike it is a reminder of why we're here: to do our best and hope to win.

If you were able to see detail in the photo you might have a chuckle. Most of the plaques are for QRP. That isn't the category most contesters care for. Indeed, some have told me outright that they don't consider QRP a sensible cateogory to enter. Obviously I disagree. There are plaques on the wall for two overall wins in CQ WW SSB and another two in ARRL Sweepstakes. 

I've been #2 or #3 several times in past contests but there are no plaques given for that. There can only be one winner. However I do have what could only be called "consolation" awards, such as those for winning Canada in a major contest. Since our contesting community is relatively small that isn't a great achievement. Nevertheless those plaques are now on the wall with all the rest.

That isn't so terrible here in the Great White North since, for example, in CQ WW we are in a poor position to win plaques for the major categories. Propagation isn't favourable, scoring for US and Canada is asymmetric (thus the separate range of US plaques for which we don't qualify) and we lose in competition with the Caribbean for North American plaques. We take what we can get! 

I know many contesters who strive to win plaques. When an overall win isn't possible due to geography, station, competition or other reasons they choose a category they can win. Otherwise unpopular categories may seem enticing. These may be for lower power levels (LP or QRP), single band, assisted vs non-assisted, etc. There's nothing wrong with that if that's what you desire. 

I am more interested in having fun and achieving a personal goal. I don't even care if my choice of category isn't officially recognized. Plaques are never on my radar. When one shows up in (or more likely on) my mailbox it is almost always a surprise.

There are also no plaques on my wall for DXCC or other non-contest operating awards. As I've mentioned more than just once on this blog that I don't need formal recognition to celebrate my achievements. I have 315 countries confirmed on LOTW, and over 100 similarly confirmed on all bands from 160 to 6 meters. My DXCC Challenge count has almost reached 2300 despite the award not being an objective. I know what I've done and that's good enough for me.

It was interesting when a friend (Dave VE3KG) recently sent me the adjacent photo. Doug VE3KKB was digging through his boxes and found this plaque from a contest we did together, along with Brian VE3CRG, well over 40 years ago. That was in the time of paper logs, hybrid tube/transistor radios and no spotting networks. His call and mine have since changed yet here we are in 2026 still enthusiastic about the hobby and still contesting.

I vaguely recall that we entered M/M since M/S, which we usually entered, didn't allow a group of keen operators as much time in the chair as we'd like. How we won I'll never know. 

Look at that score. Can you imagine winning WPX in 2026 with a score that low? Single ops nowadays score far higher than we did M/M. Of course we now have assistance, SO2R, more agile technology and, specific to WPX, far more prefix multipliers on offer. 

The special prefix helped. Those were less common back then.

Although times are ever changing it is fun to reminisce a little about how it used to be. We had a lot of fun contesting then and we still do today. I am expecting to have a guest op for WPX SSB later this month. WPX is no longer one of my favourite contests so I'm happy to clear the way my calendar for someone else to aim for a contest plaque. I hope that he achieves his goal.

Puzzling Digital DXing Tactics

DXpeditions to rare entities can bring out the worst in people. The pile ups are unruly, DQRM is rampant and every complaint imaginable is seen on social media and spotting networks. I expected to see all of it during the 3Y0K Bouvet Island operation and I have, regrettably, not been disappointed. A few well known DXers and contesters are among the worst offenders.

After so long in the hobby none of it surprises me. Technology has changed the ways in which the nonsense is performed, but human behaviour remains the same. I simply work around it and marvel at the human comedy of my fellow DXers. If working rare DX or winning a contest were easy we wouldn't value it as much. Nobody is entitled to a QSO.

I thought I'd seen it all but I was wrong. There is a new kind of bad behaviour. Perhaps I should not have been surprised that digital modes, with the need for different tactics to work the rare DX, breeds new forms of poor DXing behaviour. 

My own operating on digital modes (and by that I primary mean FT8) is limited. I do it on 6 meters where it does wonders, a little on 160, when CW activity is absent, and on other bands only as insurance contacts when I have not yet successfully worked a DXpedition on CW or SSB. It may be that I've been slower to notice these digital antics than some others.

I won't bore you with multiple screenshots of what I've seen even though a lot of it is amusing. Some of these antics include:

• Wrong call sign (e.g. 3Y0J and 3YOK): These were obviously entered manually. This wouldn't happen if they clicked on an actual message from 3Y0K. Presumably they can't copy 3Y0K yet they insist on calling.
• Transmitting on the wrong period: The DXpedition is on the first (even) periods (00/30) and the callers are on the opposite periods (15/45). Callers on 00/30 aren't copying 3Y0K or carelessly override the convenience feature of letting the software choose the correct period.
• Passersby calling the callers: Amazingly a few of the called answer. I guess those pile ups are where the "work everybody" crowd goes to hunt fresh meat.

Now let's look at the one screenshot I did take. I chose it since it captures several kinds of odd behaviour. The frequency is 1836 kHz, which I have been periodically monitoring since 160 meters is the one remaining band where I'd like to work 3Y0K. Call signs of the callers have been obscured.

The first two messages are pretty innocuous. These appear to be stations legitimately calling the DXpedition. However, while there was concurrent evidence that they were being weakly heard in Europe it was very improbable that they were heard in my part of the world (I'm in FN24). I have an extensive system of Beverage receive antennas with which I hear very well and I didn't copy 3Y0K at all. The station in FN31 is one I don't ever recall hearing on top band.

These may both be examples of blind calling. While this may seem pointless it does have one possible benefit. That is, if 3Y0K is not actively CQing but the operators are monitoring 1836 kHz for signs of an opening, successful copy of these transmissions would get their attention. 

The number of stations doing this sharply increases as sunrise in Bouvet approaches later in our evening -- their sunrise is approximately 0525Z. Successful stations have noted that their signal peaks about 10 to 15 minutes before then if it appears at all. I am not aware of a northeast NA station hearing or working 3Y0K early in our evening, 5 hours before their sunrise.

Another surprisingly common sight is stations sending an R-nn message seemingly out of the blue. Did they really copy a signal report from 3Y0K? That northeast NA station is very unlikely to have heard them when I and other well-equipped top band stations have not. I see the tactic done by many stations when 3Y0K is weakly heard (on all bands, not just 160) and few if any are heard by the DXpedition.

What is going on? I have heard opinions that it is a harebrained tactic to illegitimately slip into the log. Pretend that you received their report and hope that they copy one out of the multitude of R-nn messages sent by the station. The hope is that the DXpedition op clicks on it to send the RR73 and thus you magically appear in the 3Y0K log without every copying them. Unbelievable! Yet many persist.

Any DXpedition, and indeed almost every FT8 operator, uses auto-sequence. Therefore the tactic does not work. Even were they not using auto-sequence it would take a particularly dim DXpedition operator to click on that message to send an RR73 and then log the QSO. On 160 this is even less likely to happen since if you're having that much difficulty it is very unlikely that the R-nn message would ever be copied by them.

You may have also noted that this station did not actually copy the DXpedition and typed an incorrect call. That will certainly not work! It takes a especially shallow intellect to believe that DXpedition ops are so incompetent.

The last example from the screenshot is of a station responding to a phantom decode. That isn't uncommon. With stations configured for automatic responses, operators that don't pay attention or lack an understanding of international call sign prefixes and structure, regularly fall into this trap. It is more interesting in this case since that station was not CQing or blindly calling 3Y0K. How did it come about, and on 1836 kHz which is not the designated FT8 waterhole? It's a mystery, but an amusing mystery.

I have to wonder how these hams perceive DXing and the technology. Don't they think they ought to be able to copy the station they're calling? On CW or SSB this can be difficult due to weak signals or DQRM but not on FT8 -- the signal is decoded or it's not. Is getting in the DXpedition's log more important than legitimately working them? If that's all you want, send them a "donation" and thank them for working you on 160 meters at such and such a time. While that won't work with 3Y0K it is unfortunately that a few DX operators will confirm those donations.

As I type these words I have heard 3Y0K only once on 160 meters. First on CW and then FT8, at the anointed pre-sunrise opening. They switched to digital when they had difficulty copying the CW callers. Unfortunately I failed to get their attention on CW and I decoded them just once on FT8 before the brief opening faded. Oh well. I'll have to keep trying. With the switch to daylight time last weekend it has gotten harder since 0525Z is now 1:25 AM local time. I can't (won't) do that every night.

As the DXpedition continues the DQRM has subsided. I guess the perpetrators got bored. From my QTH they have mostly been off the side of the beam (Europe) or inside the skip zone (eastern NA). Frustrated callers continue to vent on the DX spotting networks to little effect since the DXpedition doesn't monitor spots. Better to send an email to the pilot for your region.

With a little luck (and sleep deprivation) I may yet work them on 160. Even if I don't I've done well and have nothing to complain about. I can claim an achievement rarer than a QSO with Bouvet: an email! This came to us from a friend on the DXpedition. It was great to hear from him and it put a smile on my face. I hope that the rest of their stay is without drama and that they all get home safely. Many hams are now one step closer to DXCC Honor Roll.

3-element 20M Yagi (Constrained) Optimization

I am designing several small mono-band yagis to replace the TH6. The venerable tri-band yagi is fixed south at an intermediate height (~25 meters) for working the southeast US, Caribbean and South America. It's deficits are that it is narrow band (high Q), high loss (traps) and not sharable during multi-ops. It's also very very old.

A no-trap tri-band yagi like the Skyhawk fits the bill when combined with a triplexer and set of high power BPF. However that is a very expensive solution at >$4,000 if the equipment is purchased new. They are not often found on the used market. I am fortunate to have purchased a used Skyhawk far below the new price. It is rotatable at about 21 meters height.

A few small (smallish) yagis are not expensive to build since I have ample aluminum in my stock. I also do not anticipate difficulty side mounting these yagis where they can be effective without significantly interacting with the stacks for the high bands. Additional switching hardware will have to be built and fit into the station automation, but that isn't difficult. Low loss transmission lines are mostly already in place.

I decided to abandon my attempt to design a 2-element 20 meter yagi with the attributes I want. Performance of every 2-element variation, including Moxons, have been poor in some respect. These include gain, gain bandwidth, SWR or mechanical robustness. My revised objective is an ordinary 3-element yagi. I have all of the material on hand, although I'd have preferred not to use so much of it. Hopefully I can replenish my stock through more scrounging.

Even for such a simple antenna there are many interdependent parameters. For the design process I have fixed the boom length to 7 meters (23') since I can build a boom that length from available tubes and it is sufficient for good performance. I have further fixed the position of the DE (driven element) at 40 cm (16") behind boom centre: closer to the reflector than the director. It is a position that is conducive to achieving good performance that is used for most yagi designs.

Fixing certain parameters simplifies the design and optimization but can omit some high performance solutions. Based on my experience these choices are acceptable since excellent designs are readily obtainable by fixing these particular parameters. 

Since this is a design exercise rather than a construction plan, all of the elements are constant diameter 25 mm wires. A taper schedule can be added later with negligible change to the yagi's performance. Using EZNEC, I compared NEC2 and NEC5 then decided to stick with NEC5 for the remainder of the design process. Gain is virtually identical between NEC2 and NEC5, with small variations in F/B and feed point impedance.

The modelled feed point matching network is a beta (hairpin) match. The length of the DE is shorter than resonance to provide series capacitive reactance. The length and impedance of the shorted stub determine the shunt inductance. These parameters are easy to adjust in the model and in the field. A beta match requires the DE to be electrically isolated from the boom, unlike the gamma matches I typically use. Mechanical complexity is traded for tuning simplicity, but either is acceptable. A CMC (common mode choke) is advisable for any feed system.

With the selected fixed parameters we have the following degrees of freedom in a 3-element yagi:

• Lengths of the director and reflector
• Ratio of director to reflector lengths 

Really, that's about it. Only a 2-element yagi is simpler. Yagis with 4 or more elements are more difficult to optimize since there are so many more variables. Luckily there are numerous published and optimized yagi designs so that in most cases you can look them up in the ARRL Antenna Book and elsewhere. But beware of unverified designs based on boasting, poor methodology, old myths that refuse to die and opinions not backed up by engineering.

Even for a simple 3-element design like this one there are a several things to keep in mind:

• Maximum gain is largely determined by boom length, not the number of elements. Once a boom length is selected, we choose the number of elements needed to ensure sufficient coupling among them to enable the performance objectives to be attained.
• The length of the DE is irrelevant to performance. It only needs to be close enough to the lengths of the parasitic elements to effectively couple. Modest shortening of the DE to transform the feed point impedance to 50 Ω has negligible performance impact. 
• For a 3-element yagi, gain rises with frequency and is typically maximum beyond the operating bandwidth. For 2-element yagis maximum gain is below the operating bandwidth. Yagis with 4 or more elements are similar to those with 3 elements in this respect but with more variability. 
• Smaller reflector to director length ratios give higher gain and narrower SWR bandwidth. Too small a ratio can result in an antenna gain that cannot be effectively matched and requires large diameter elements (not wire) to avoid ohmic loss in the elements. This is due to the low radiation resistance where gain is maximum. That is expected and not a coincidence.
• High reflector to director length ratios can in extreme cases be fed without a matching network since their feed point impedances can be close to 50 Ω. However, that feature comes at the cost of performance. 

For this design exercise I modelled a 3-element yagi with a parasitic element "spread" of 6%. That is, the reflector is 6% longer than resonance for the operating bandwidth and the director 6% shorter. I then adjusted the DE and beta match for an SWR of 1 at mid-band: 14.175 MHz. That was my baseline. From that baseline I increased and decreased the reflector to director ratio to bracket a reasonable range of performance metrics.

To demonstrate the results I will only present 3 of those spreads: 5%, 7% and 10%. Outside that range the performance metrics are not to my liking. Others could perhaps justify alternative designs for specific applications. My primary objective is as follows:

• Maximum gain for an SWR lower than 1.5 across the 20 meter band: 14.0 to 14.35 MHz. 

I am not concerned with optimizing F/B, since the antenna is primarily for contests in which I am happy to hear and work stations off the main lobe. The low SWR objective is to be compatible with solid state amplifiers that have no ATU. This is an objective to enable maximum operating agility. The TH6, like any loaded or trapped yagi, performs poorly in this respect.

Well, that's a long preamble to set up what will be a brief presentation of my modelling results. So let's have a look.

From this graph it should begin to become clear why I selected the spread values that I did. Above 7% the 1.5 SWR is too narrow, and is indeed little better than the TH6. The SWR bandwidth at a 10% spread seems enticing until we consider performance.

To display F/B and gain on a single chart I expanded it vertically. The colour scheme may be a little confusing but good enough to convey the data.

There is a significant gain difference among the three designs. As already described, gain rises toward the top of the band and narrower spreads have higher gain. The range varies between 1 and 1.5 db. 

Is that a significant difference for on-air performance? Many hams will say no. However, for contest use there is a demonstrable difference. It may not be immediately evident in use since QSB obscures the difference. Even 1 db will get you through the pile ups faster and when running you'll attract more callers.

For me the lower gain for the 10% spread is undesirable. At 7% gain is only 0.5 db below that of the yagi with a 5% spread, and the SWR objective is met, just barely. The parameters of the beta match (not shown) are easily achievable without compromising construction or efficiency.

While F/B is not strongly favoured for my intended purposes, the relatively poor F/B with a 10% spread is concerning. It can be somewhat improved by adjusting yagi parameters that I fixed for this modelling exercise, though not by much. A 10% is too wide. Yet it is interesting that many commercial designs within this range. Perhaps the full-band low SWR is effective marketing. 

F/B for 5% and 7% spreads are different but comparable. Considering full band performance, the 7% yagi is perhaps marginally better. It isn't worth fussing over since the difference will be difficult to notice in practice and even small interactions with the tower, guys and other antennas near and far will alter both performance charts such that it would be hard to prefer one over the other. 

Unlike gain and SWR, the overall pattern is acutely sensitive to interactions. This is because of the exact balance of amplitude and phase to substantially cancel radiation in those many directions.

My hope is that this deliberately constrained analysis of 3-element yagis helps to clarify necessary trade offs in any yagi design. There really isn't anything new in this article. Despite this, the analysis has clarified how to proceed.

My choice is a 7% spread. I have already begun collecting the material and construction will proceed this spring. Replacement of the TH6 with the new yagi may be delayed so that I don't lose 10 and 15 meters until yagis for those bands are ready. I want all three yagis ready for the fall contest season.

I am planning construction features to achieve more than the basic objectives. For example, managing interaction with the nearby 40 meter Moxon. I'll report on those after the yagi has been completed, tuned and tested, along with a detailed description of the antenna. It was brutally cold this morning but the sun is shining and spring is not far off.

ARRL DX CW 2026

Once again we did M/2 from the station of my friend Vlad VE3JM. His station is similar in size to mine and he does extremely well from there. He is also a better contest operator, especially 2BSIQ, so he almost always beats me when we enter contests in the same category. This year we have a full complement of 5 operators; last year there was just the two of us when the others cancelled due to a ferocious snowstorm. This year's storm didn't impede travel even for those driving up from the Toronto area.

This edition of the ARRL DX CW contest made it clear that we are past the peak of cycle 25. Our score was lower with 5 operators than with 2 of us in 2025. Geomagnetic disturbances are up and the sunspot count is down. The latter was actually zero (0) on Monday. We are unlikely to see many contest records broken for the next half dozen years.

Although I didn't remember to take a snapshot soon enough after the contest the Sunday K-index chart tells the tale. It wasn't good. Not terrible, but definitely not good. That said, there was a lot of DX on offer and many fantastic runs. 

Although conditions affect everybody, which ought to burden competitors equally, opportunities do not skew equitably when you move a few hundred kilometers near the auroral zone. That noticably affected us, though to what degree is difficult to say. Of course our challenges pale in comparison to those even farther north. This is not an excuse but an explanation for regional variation.

This is the setup we used. From left to right are Dave VE3KG on the in-band station, Nick VE3EY on one run station and Les VE3NNT on the other run station. In the background you can see that Vlad has an outstanding set of high power filters and triplexers from VA6AM. We still had interaction issues, especially harmonics that regularly plague CW. You will regularly find yourself near those harmonics due to simple arithmetic. 

The in-band station has no filters other than what the receiver can provide, and by the separation and polarity of the antenna. The in-band antenna is a multi-band (no trap) 40-to-10 meter vertical about 100 meters from the various towers. The in-band station has no amplifier since the proximity of the antennas does not allow use of higher power without impacting the run stations. Interference in the other direction is acceptable but often problematic.

This was my first experience operating with an in-band station and I was impressed despite the inter-station interference and limited power and antenna. Many contacts and some multipliers were logged. This is important since many stations mostly run so this may be the only way to work them. It also allows the run station to keep running, and eager operators can get in there and contribute. 

The interlocks worked well (DXLog) and it was easy for the operators to learn how to coordinate. I'm tempted to add this capability to my own station. Techniques to reduce interference were discussed among the operators.

In-band capability is not a universal solution. The run stations, with higher power and superior antennas, did a lot of the work. Also, the in-band station could not be manned full time. One reason was that the in-band station had no antenna for 80 or 160 meters. The worse conditions on the second day further limited its effectiveness due to weaker signals. Working spotted stations on the run radios risked loss of the run frequency and wasting time with busted spots, both human and skimmer generated. There were a lot of busted spots that wasted our time.

Propagation played a critical role in our competitiveness. We were at a disadvantage compared to those to the south and therefore farther from the auroral oval. That's not a complaint, just a feature of where we live. It happens whenever conditions are disturbed or marginal. 

The following is a brief description of several interesting propagation factors that we experienced, both pro and con:

• On Sunday morning when 10 meter propagation to Europe was poor, one of our operators (VE3EY) turned the 7-element yagi east, and then a little further south. Signals from Europe strengthened and the rate shot up. That was a smart move. I've known that this can happen for more than 40 years yet never suspected skew path this weekend. It is a common occurrence during solar minima years that Europeans on 10 meter peak towards the sun. Whether scatter or true skew path it is worth turning the yagi to check for this phenomenon. More southerly areas get more sunlight and therefore have a higher MUF.
  
• This weekend provided another lesson in paying less attention to SSN (sunspot number) and more to SFI (10.7 cm solar flux index). On Sunday the SSN was 0. Even so the high bands were open. SFI is a better proxy for ionospheric MUF.
• The first night and to a lesser extent the second, 40 meters stayed open to Europe until long after their sunrise. This often happens when geomagnetic conditions are quiet and the solar flux is low. Signals get weaker as the sun rises in Europe but remain workable. Unlike in CQ WW they stay on the low bands rather than moving to the high bands since they can only work North Americans. My rate was very good for longer than one might think possible.
• 20 meters opened for about one hour overnight to Europe at the same time 40 was still going strong after their sunrise. Sometimes it happens and sometimes not, so you must pay attention. After that hour the band died and didn't reopen until a little before our sunrise.
• 80 meter conditions to Japan and the north Pacific were better than expected. Overnight we worked quite a few stations. Signals were weak but many stations were workable. We usually can't work east Asia until our sunrise enhancement. Several welcome multipliers were logged on 80 this way. 

Despite excellent activity our results were down. That mirrors the experience of others. Propagation played a part as did participation. CW in particular is less popular with younger generations, especially in North America. Outside VE/W there is less interest in this contest since it is more of a QSO party than a global contest. For those on the other side of the globe there is little to work, so why would they bother. We should be thankful to those that participate and make the contest what it is.

It must also be noted that not everyone taking part is familiar with the rules. We had many US callers and even a few from Canada. They are of course worth zero points. As for dupes, it is better to work them than to try to explain the rules to each caller or to ignore or admonish them. I would never want to discourage their enthusiasm. If they encounter rudeness these casual operators won't call you in the next contest when the points they give you will contribute to your success.

As usual, we used the online scoreboard. I rarely use it when I operate alone, but it was interesting to see how our nearest competitors were doing. In ARRL DX we are on an equal footing with US participants so the comparisons are meaningful. In some respects watching the scoreboard was discouraging since there was little we could do about what we witnessed. We were already motivated and working hard on our score as I am sure were the others. 

I consider the scoreboard a needless distraction which is why I have yet to use it for my single op contest efforts. It wouldn't change what I do. Many others feel differently. However I see its value to non-participants that want to follow the competitors. In the future I may post my score even though I am unlikely to look at the scoreboard during the contest. Perhaps my opinion will change in the future.

I'll close with a note about technology and training. Most of us don't use DXLog in our own stations. I only use it when operating at Vlad's station. As I have with N1MM, his station automation systems are tightly integrated with DXLog. There is a learning curve. A crib sheet with common commands isn't really adequate since these software packages are feature rich and can behave in ways that neophytes can't predict or deal with. All we could do was fumble or call out for help when in trouble.

The only solution is pre-contest training. That means using and studying the software before the contest weekend. That is in addition to learning about the antennas and selection process in a large station. There is a lot to digest and use effectively, or at least with minimal friction. It is worth consideration in advance of your next multi-op contest, whether at your station or elsewhere.