[Antennas] RE: no radial vertical antennas

[DJED1@aol.com]

It certainly is possible to build vertical dipoles- by the tens of thousands 
as it turns out.  the US Army has been using vertical dipoles for VHF 
tactical communications for over 30 years. While it is true that they would 
do better with a big ground screen, that's not a good solution for your 
average tank.  The older antenna is now available in surplus, and is called 
the AS-1729.  It is a vertical, center-fed dipole, with coax run down the 
center of the lower half of the antenna.  the base contains a ferrite choke 
to isloate the feed line, and also a mechanically switched tuning network.  
The tuner is controlled by the radio.  The isolation makes the antenna 
impedance much less sensitive to the vehicle and the ground it is on, so it 
is a good choice for the application.  Newer designs have eliminated the 
tuning and are broadband to accommodate frequency hopping radios.  the Army 
buys 25000 to 50000 a year!
Ed