Wednesday, March 19, 2014

Late-winter Doldrums

Too cold to work on antennas but so close to warmer weather that I can't bring myself to only plan but not do anything outside. I have pretty much convinced myself that I need to take a step up with antennas and possibly with power. QRP with small antennas has been great fun this past year, it just isn't what I want to do forever.

The spring equinox is as good an opportunity as any to look back at my DX accomplishments over the past 14 months with QRP (10 watts maximum), CW only, and simple, low wire antennas, since ending my 20-years hiatus from amateur radio. That will be a good base from which to look forward to the rest of 2014 and beyond.


I now have over 100 countries on each of 40, 30, 20, 17, 15 and 10 meters. The last band on which I achieved this mark was 17 meters, where I now have 102 worked. I was surprised at my low country count on 17, so I had to catch up. This is most likely due to it not being a contest band. I have mostly worked 17 meters to catch some rare DXpeditions (FT5ZM, VU7AG, etc.). I have yet to work F and G on that band. Go figure.

Unsurprisingly 20 meters is my best band with 153 worked. All other bands are in between. I don't have antennas up for 6, 12, 80 and 160 meters so apart from a smattering of contacts using a tuner my efforts there are approximately nil.

My overall total countries is 193 worked. It's slow going at this point. I have heard lots of workable stations in perhaps 50 more countries but my puny signal was not heard. My objective of reaching 200 countries with my current station may not happen before I begin antenna work this year.


Logbook of the World has proved to be a great way to confirm countries for DXCC credit. As of my last upload at the end of February I have 145 countries confirmed through LoTW. A confirmation rate of 75% is quite good.

On a per-band basis I have noticed an interesting trend. On the bands where contests are held (80, 40, 20, 15, 10) my confirmation rate is ~65%. On the other bands (30, 17) the rate is ~50%. I suspect the reason is that contesters are more likely than others to upload their logs to LoTW. Many DXpeditions delay uploads or do not use LoTW.


My DX totals were enhanced by participation in contests, both semi-serious and serious. However on deeper reflection my results mask an unpleasant truth: I am mostly working only big-gun contesters, especially on 40 meters.

It is by working the big guns on every band that my QSO totals get as high as they do. I can't run stations (sit on a frequency and call CQ or QRZ, and get answers) and I don't work many of the stations that have similarly puny signals or even those with average signals. I remember one very weak European on 15 meters that answered my CQ, and later discovering he's a regular contester in the same QRP category as myself. That's how I must sound to most stations that I call. That's why I have to call the big guns.

This is easily noticed in the logging software by the number of big guns that I've worked on every band. All it takes is working 100 of these stations across the bands to reach 500 QSOs. In DX contests where VE can work W/K there are even more of these stations to work.

Whether for purely contesting objectives or as a path to DX success I need better (bigger) antennas.


Looking forward to 2014 I will briefly outline the topics that are of interest to me in my pursuit of better antennas. If you follow the blog you will likely see one or several articles on each this year.


With some reservations in advance of a post-winter inspection, I believe that my opportunistically-guyed small tower passed the weather challenge quite well. This included not only cold and ice, but also some strong winds. If it checks out I plan to install a more substantial tower, though still one that would be considered light duty.

My objective is simple enough: a 3-element yagi at 14 or 15 meters height for 3 or more of the high bands will provide 10 db or more of gain over the multi-band dipole and inverted vee I currently use. Part of the improvement is antenna gain and part is greater height. If I decide to stay with QRP this change alone will make me significantly more competitive in DX pile-ups and contests. Jumping up to 100 watts would add a further 10 db gain.

My plan, if I come across something cheap and used, is a Delhi (now Wade) DMX-52. I can mount this in the same location and manner as the current Golden Nugget tower (Site C). I prefer this approach so that no concrete base is required and I stay under the municipal/federal "duty to notify" regulatory requirements that are in effect for structures higher than 15 meters above grade.

If that goes well (and I don't again lose interest in the hobby) I will consider a more permanent, stronger and higher tower in 2015. Any such tower must go to Site D in order to be clear of the septic system tile bed, yet keep a decent distance from the rear property line.

High-performance yagis for the high bands

A light-duty tower requires an antenna (or antennas) that don't stress the tower plus guying. The TH6DXX I have in storage is heavy and has more wind area that I am comfortable putting on a tower of this class. It also doesn't include 17 and 12 meters.

A rotatable wire yagi is more suitable. I am beginning to seriously look at the 5-band Spiderbeam. From people I've talked to it appears to be up to surviving our local weather and its performance claims appear to be legitimate. I found an EZNEC model of the 3-band version (20, 15, 10) and have started experimenting with it. A Hexbeam is also a possibility, except that it has a large vertical height that would easily put it over my 15 meters height limit when placed on a 14 meters high tower.

If I get ambitious I'll also put up a short yagi on 6 meters. If I don't get around to it by July I will probably not do so at all this year since sporadic-E season will have already come and gone.

Low-bands antennas

For 40 meters I may replace the delta loop with a 2-element switchable array, probably the diamond loop array I have already designed. I will need to supplement this with a dipole, possibly on the house-bracketed mast, to fill the side nodes of the array and to effectively work the northeast US in contests.

Getting an effective DX antenna on 80 meters will be difficult. Something like an inductor-loaded half-sloper might work out. However there is the potential to interfere with the performance of the 40 meters array, and there is an unknown capacitive loading due to the wire high-bands yagi. I don't need a great antenna for 80 meters, just one that will collect multipliers in contests and allow me to do some DXing.

I have no plan for 160 meters in 2014.

I have been idly playing with EZNEC to model a variety of potential 40 and 80 meters antennas for 2015, in the case that I put up a proper tower. The main challenge is getting a high-performance antenna to fit the 15 meters (50') width of my property. For instance, a rotatable 40 meters yagi cannot have elements longer than 13 meters. Managing loss in short antennas is the objective, and therefore I have started to explore in that direction.

When these models reach a suitable level of maturity I will write about them.

Antenna interactions

My immediate interests with respect to antenna interactions fall into two categories:
  • Interactions among many antennas sharing one tower
  • Interactions among stacked, rotatable yagis
In 2014 the first category is of most interest to me. That is why I spent some effort investigating how a vertically-polarized low-bands antenna interacts with a tower, and how to resolve problems.

The second category is more of a future concerns, but an important one. There are specific ideas I want to dig into that may shed more light on this question. Most hams go by rough, and often unverified rules-of-thumb, while other elect to ignore the issue or go to unfortunate extremes. For example, loss of structural integrity by using masts that extend far above the tower top.

Wind load

Because of my choice of tower and guying arrangement I have a renewed interest in acquiring a better understanding of wind load. In particular, the quantified wind load of antennas and other tower loads, and the behaviour and real carrying capacity of towers. This will also be useful should I erect a larger tower in 2015.

The big problems with wind load is that the marketing of antennas and, to a lesser extent, towers does not provide reliable figures. It is quite easy to find quoted square footage of popular antennas that cover an almost 2-to-1 range of values. Towers manufacturers are typically better at providing good data, if you know how to interpret and apply the data. These data are critical not only to build a robust installation but also to pass the requirements for a building permit.

This is not an unfamiliar area to me since I have put up countless towers and antennas over the decades. I have seen many towers and antennas fail as well. There is good information out there, which I have begun to collect.

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