[TowerTalk] Omnidirectional antenna for domestic contests

[Jim Brown]

On Tue,10/6/2015 2:29 PM, Kim Elmore wrote:
> Which should work better for domestic contests:)

Not necessarily -- much of that is more urban legend than fact. It's a 
big country, and depending on conditions and the band you're working, 
many stations you want to work will be a low angle path. Also, inverse 
square law says that we lose 6dB per doubling of distance, so you need 
more signal to work those long distances than the shorter ones.

W6GJB and I just built a loaded vertical dipole for 80M for use in CQP 
and on FD. It's designed so that old men can put it up without hurting 
themselves, with the objective of beating an inverted Vee with apex at 
42 ft, which we have a good way of rigging. A few weeks ago, we set up 
both antennas in GJB's pasture and did a lot of RBN testing, and plotted 
the results vs distance. The low angle vertical beat the inverted vee at 
almost all distances. AND -- many stations heard the vertical that 
didn't hear the inverted Vee, but only one or two heard the inverted Vee 
and didn't hear the vertical. Modeling predicted that the vertical would 
be 5 dB better, and the RBN clearly results showed that trend.

To do our RBN testing, we alternated between antennas using a different 
call for each, making a couple of calls on a frequency, then QSYing and 
repeating. The purpose, of course, is to average out the results of QSB.

Unfortunately, when we set it up for CQP, the Spiderbeam telescoping 
pole that made up the top half of the antenna broke in gusty winds that 
blew in late Saturday afternoon, so we didn't get to use it that night 
for the contest.

73, Jim K9YC