Where'd he go?
During this hiatus I have been trying to finish a draft of a white paper entitled Antennas for 100 Pound DXpeditions. You can find this in my download area. The file to download is named "Antennas-for-100.pdf" and it is approximately 26 MB in size so be patient.
I was not entirely happy with things I had done on Montserrat. Further, some of the "conventional wisdom" I received on various Buddipole configurations did not make sense to me (though I was reluctant to argue at the time). I decided not long after returning home that what was needed was a disciplined and scientific approach to this problem. What do these antennas do? How well do they perform? What configurations work? Which configurations are unsatisfactory?
I begin to answer some of these questions in this white paper. Here are some conclusions I've drawn on the Buddipole, for example:
- No short whips -- The standard Buddipole configuration sold comes with stainless steel whips just under 6 foot long. They are too short for reasonable HF work. I will still use them for my 6 meter Yagi made from Buddipole parts, but I'll not use them again for HF. Period.
- For 20 meters and up, no coils -- The standard Buddipole configurations specify coils and particular taps for the bands. I believe it makes more sense to remove the coils from the bag and substitute long whips (9 foot 4 inches) and two extra antenna arms. That can be used to make the antenna described below.
- Only full-sized verticals for the Buddipole -- In the end, after looking at configuration after configuration for the Buddipole, the only one that really performs well is the full-size vertical with no coils and four radials. The 20 meter version requires four arms and a fully extended long whip, but it is great on that band.
- At least 4 radials -- I've read lots of discussions about using just one sloping radial for the Buddipole. After extensive modeling, I am convinced this is a very bad idea. At least four radials are needed. Four elevated radials help create an antenna that performs very well. The one radial approach gives you a bizarre pattern with deep nulls.
I also analyze two other antennas: the Force-12 Sigma-5 and the TW Antennas Traveler. For their size, both antennas performed very well. The fact that they are multiband antennas (5 bands 10-12-15-17-20) fed with a single feed line means significant savings in coax weight. Instead of running five runs of small coax for five single band antennas, one could run a single length of high quality coax, reducing signal loss and still saving weight. It is important to assess whole systems of things, not just the pieces like the antenna.
I have presentations to give to local clubs beginning in about two weeks. My new slides are not done. So, I will likely disappear again for a while. Comments on the early draft of this white paper are encouraged. Let me know what you think.