Wednesday, October 15, 2014

Two Weeks with a Yagi

Of course a yagi at 15 meters height is going to perform better than an inverted vee at a similar apex height. In that respect what more could possibly be said other than the recently-raised Explorer 14 works great? I think there is more to be said, even if the news is less than revolutionary.

This is especially true when QRP is brought into the mix. Before talking more about the yagi's performance in my QRP station I think it would help to review the several distinct philosophies regarding QRP:
  1. Striving to do the most with the least. Everything is small, not just power, but aim for maximum results.
  2. Low impact amateur radio.
  3. Portability and emergency use.
  4. Level playing field, except for power. Otherwise, operate like the majority.
This diversity of approaches to QRP struck home for me in a recent exchange on a contest forum. There are those who operate QRP contests and there are those who operate contests with QRP. I fall into the latter category. Further, my QRP philosophy is that of the last bullet in the above list (though I briefly started off at #2 when I returned to the hobby almost 2 years ago). Thus my drive toward larger, better antennas in my current domestic situation. Which brings me back to the yagi.

As I hinted in my first experiences with the new yagi, it is a clear winner over the inverted vee. While the fact alone is obvious I wanted to quantify it. My original estimate was a broadside improvement of about 10 db. This is a combination of forward gain and height. Height contributes two ways: lower radiation angle, and rising above the local pattern-modifying, metal-rich suburban houses.

Accurate A-B comparisons are difficult due to Faraday rotation, path-dependent elevation angles on every signal, and other effects. These create time-dependent gain differentials and pattern sensitivities. Even without the ability to properly quantify the improvement, the testing I've done over the previous two weeks convinces me that my expectation of a 10 db improvement has been borne out.

My observations and results of my first 2 weeks with the yagi comprise the rest of this article. My next article will get back to antennas. In particular the first of the low-band wires I've been planning.


When I put up the yagi 2 weeks ago I had 207 countries (QRP & CW, starting in January 2013). I now have 215. Good propagation and a number of DXpeditions helped. Actually only 6 of the 8 new ones were accomplished with the yagi. I first worked VK9DLX (Lord Howe I.) on 30 and YJ0X (Vanuatu) on 40. The inverted vee is still pulling its weight.

I am finally having more success with long path DX: western Pacific, Indian Ocean and east/southeast Asia. But it wasn't just new countries. I added many more band-countries. Even casual DXing is becoming more casual since more stations can copy me well.


QRP in a pile-up remains challenging, though less so than before. I can mix it up in the pile-ups. If they're not too intense I can get through just fine. The past 2 weeks these included C21GC, S79KB and T30D.


I contest-tested the antenna in the California QSO Party. For the 9 hours I operated I put in a decent score. I had substantially more success that in the Florida QSO party earlier this year. Few were the stations that didn't hear me -- for some reason (perhaps QRM at the other end) those were mostly on 10 meters. This also goes for SSB, which I didn't even bother with in FQP.

My next test of the yagi is CQ WW that is coming up later this month. Although I was briefly tempted to accept an invitation to join a multi-op operation from a large station.


For contests my plan was to supplement the yagi with the inverted vee on 20 and 15 for the purpose of diversity. That is, to catch openings and quickly work stations off the main beam direction of the yagi. For example, in late afternoon Europe is good for running stations on 20 meters, but there are also openings to needed multipliers in Asia and the Pacific.

That might not work out. The yagi is so much better than the inverted vee that other than off the sides the yagi outperforms it. Even with the F/B of the beam, signals off the back are usually no worse than on the inverted vee. I will have to take this into account during contests.


My unconventional guying arrangement (trees) necessarily includes a measure of uncertainty. The trees must not only support themselves in the wind but also the lateral and vertical (upward) force of the guys due to the same wind. This is a topic I want to explore further in a future article.

The tower survived a brutal wind storm, before the yagi was raised. My station was right in the cross-hairs of the greatest sustained wind (90 to 95 kph) and gusts (over 120 kph). It was hard to watch, yet I did. The tower performed admirably. Or perhaps I should say the trees performed admirably.

The question is whether the added load of the yagi would have had the same successful outcome. My calculations say 'yes' but I can't be certain. This week we had some moderate winds with gusts up to 70 kph. I monitored the changing tension on the most windward guy to gauge the stress placed on the tree anchors.
There were no surprises.

WARC bands

I now know that I am missing on 17 meters by only having the inverted vee. If I had a yagi to cover 17 and 12 I could boost my success. But a compromise was necessary, and I opted for a tri-band yagi for best performance on the contesting bands rather than more modest performance on all bands from 20 to 10. Since I don't care too much for 12 meters it is only 17 meters where I notice the lack of gain. I can live with that for the next year.

No comments:

Post a Comment

All comments are moderated, and should appear within one day of submission.