[TowerTalk] Yardley Beers' Symmetrical Antenna

[Jim Thomson]

Date: Thu, 23 Feb 2017 11:24:05 -0400
From: Herbert Schoenbohm <herbert.schoenbohm at gmail.com>
To: towertalk at contesting.com
Subject: Re: [TowerTalk] Yardley Beers' Symmetrical Antenna

Perhaps the simplest antenna to cover both 160 and 80 is the Inverted L 
which is 3/8th wave on 160 and turns out to be 3/4 wave on 80.  The feed 
point on 160 can be tuned to resonance with a series variable capacitor 
about 350 pf and on 80 the capacitor is merely bridged to give you a 
reasonable match on 80.  Like any inverted "V" it is good to have as 
much vertical portion height as possible.  If the support is a metal 
tower you should try to get some distance of the inverted l from 
it....at least 30-50 feet to avoid interaction.  The top portion can 
slope down to near ground level if that is the best you can do. I would 
start with a total wire length of 190 feet and fold back the ends until 
you got the best match for 80.



Herb Schoenbohm, KV4FZ

##  very slick indeed. The .75 wave on 80m would, or should be resonant, just like
using a 40m  GP on its 3rd harmonic on 15m. 

##  No big deal to shunt out the 160m series cap, when using 80m., a simple relay
will suffice, or a small contactor, to increase V breakdown  across its series contacts.

Dunno why I didnt think of that dual 160-80m before, its simple to implement.   
A buddy had a 160m  inverted L, but ran the vertical wire parallel to the 60 ft tall
tower, maybe spaced out 3 ft from the tower.    Just before top of tower, it then
went horizontal.    He used the well casing for a ground, no radials.  Worked superb
but he was right across the street  from the ocean, which makes all the difference. 

Jim   VE7RF