I think Jeff's article is excellent and I sure wish we could see more
articles along these lines on this reflector. Especially since
antennas are such an important aspect of contesting.
Cebrik's web site contains a world of great information about
antennas. He is obviously a master at squeaking 'max gain' out of
various configurations of antennas, information you could not find
otherwise. But one must read the analysis quite carefully. As in the
case of Jeff's appropriately referenced web page, Cebrik's 'max gain'
is measured in tenths of dB's, typical differences of max gain for
various physical configurations are calculated to be from 0.01dB to
0.10 dB, which in reality does prove which physical configuration
provides 'max gain'.
What one must realize is that calculated 'max gain' and physical
reality seldom become practical. For instance, Cebrik is showing
element lengths, in inches, out to six decimal places, while we, in
fact are going to be pretty lucky to make our physical measurements
accurate to within an eighth of an inch. Then I'm sure we all realize
that Cebrik's numbers, while I'm sure are quite accurate, really are
not going to compare to our back yard, and our trees, and our ground
conductivity.
I scour through Cebrik's web site quite often to obtain ideas for
antennas. His site is where I discovered a two element Extended
Double Zepp yagi, which EZNEC shows to have a whopping 14.7 dBi gain.
But for 20m, have you ever tried to hang two #12 wires, each 88' in
length, spaced 8' apart in trees, and keep the elements carefully
aligned? Not going to happen with wires. But for higher frequencies,
such as 6m, it could be more practical, physically. Then too, with
antennas, we never get anything for 'free'. The only way you can get
more gain is to narrow the beam width. So for 14.7 dBi gain, you also
have to deal with a beam width of 33 degrees or +/- 16.5 degrees each
side of the lobe. Ever tried pointing a 33 degree beam width where it
provides max population coverage into Europe?
While in some cases it's possible to throw money into nice towers and
stacked arrays and obviously put out a very competitive signal, I
wonder what other SECC contesters 'backyard' antennas have proven to
be quite competitive for them? We may never make it into the 'top
ten' in very many contest, but we sure can make some noise!!
Good article Jeff.
Tom - W4BQF
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