Topband: Answers abt gain in bi- vs uni-directional Beverage

[Fritz Reuning K4OAQ]

Thanks to all for the great answers.  Let me try to summarize.  When I 
asked my question I was kinda balled up with my terminology.  What I was 
trying to ask was, would I lose readability of a barely readable signal 
coming from the NE when I switched the uni-directional NE Beverage to 
bi-directional.  "Readability" is more quantatively described as 
signal-to-noise ratio, I believe.  The answer is YES, not because you lose 
gain, but because you've switched in more noise - specifically, all the 
noise from the SE (I don't mean QRM from other stations).  The gain for a 
uni-directional Beverage is the same as for a bi-directional one.

So, the conclusion I've arrived at, isn't to make them switchable from uni- 
to bi-directional, BUT make them switchable from from uni-directional to 
the NE to uni-directional to the SW... back to the drawing board.

Next, I must apologize, for I mistakenly indicated these Beverage's were 
1/4 wavelength when in fact they are actually closer to 1/2 wavelength (260 
ft).  One person raised the question as to whether such a short "Beverage" 
actually provided a receiving advantage, and W4ZV modeled one 1/4 wave > 
long, 6' high and > terminated & showed it radiates straight up with no > 
directivity.

In case there's anybody out there thinking, like I once did, that you need 
a lot of real estate for a Beverage, let me share my observations.  My ant 
setup is an inv L that is fed with 50 ohm coax and no matching, about a 
four foot gnd rod at the feed point and approximately 500 ft of 2 ft wide 
chicken wire running out in a pretty random manner as radials.  I've never 
listened with a real Beverage and until the 160 contest last Dec, I've 
always suffered thru the 160 contests trying to dig stns out of the QRN. 
 Before the contest I did a "oh, what the heck" I'll just see what this 
short Beverage will do.  I made it as long as I could without getting out 
into the fields where the cows & farmer that rents the farm wouldn't get 
tangled up in it.  It was about 260 ft. of electric fence wire. I 
terminated it with a 2 watt 470 ohm resistor and used Bruce's K1FZ Beverage 
transformer.  The value of the terminating resistor was the closest I could 
find to that ubiquitous 500 ohms that I seem to read everywhere.  And 
comparable attention to detail was exhibited at the other end. (I am 
kidding, guys!)  This Beverage pointed West. I was so impressed with how it 
eliminated noise, that I put up a NE one several days later.  My off the 
top of my head guess is that these short Beverages enabled me to work an 
additional 50 or so stations in the contest.  In other contests there are 
arnd 10-15 stns that are so far in the mud that I just have to give up 
trying to dig them out.  In the contest where I used the Beverages, I think 
there might have been one stn I couldn't dig out.

A word about their directivity might be in order since a 1/4 wavelength 
Beverage shows no directivity.  A stn to the NE definitely had a better S/N 
on the NE Beverage than the W Beverage.  Analogous observations were made 
on stns to the West.  There were stns to the South that I couldn't copy 
with either Beverage and I had to use the inv L.

73,

Fritz K4OAQ
k4oaq@mindspring.com

P.S.  Modeling a 260' Beverage shows a takeoff angle of 54 degrees and
F/B of 9.5 dB at that evevation...3 dB beamwidth is 170 degrees in the
desired direction...W4ZV.


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