> Perhaps part of the problem is that these beverages have run within
> about 50 feet of my tower, but I wonder if the assembled masses
> could comment on the relative effectiveness of terminated vs un-
> terminated beverages? The books all say that unterminated beverages
> differ from terminated ones mainly in that they are bidirectional,
> but I wonder if that is too simplistic and that there may be other
> factors at work?
Hi Alan,
Bi-directional ASSUMES the antenna has zero dB reflection return
loss. If the antenna has any loss at all, it will have F/B ratio.
I've measured Beverages here (GA, 4 mS/m ) and in Ohio (15-25 mS/m)
and found the loss about 3 to 6 dB per 500 ft on 160.
That guaranties a minimum 3 to 6 dB F/B ratio without termination on
a 500 ft wire and 6 to 12 dB if the wire was 1000 ft long.
You might have to keep the antenna away from the TX antenna also, or
detune the TX antenna when on receive.
73, Tom W8JI
--
FAQ on WWW: http://www.contesting.com/towertalkfaq.html
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com
Search: http://www.contesting.com/km9p/search
|