Topband: Radials Again

[Tom Rauch]

> Presently I have 32 radials. 16 are uniform at 30 feet. 
> Two probably are
> very close to 1/4 WL, and the remainder vary from 40 to 
> 100 feet. The
> inverted L goes up to 65 feet, and then 70 feet out across 
> the house to the
> front yard, which means that radials can be placed under 
> only about 35 feet
> of the horizontal part of the antenna. I have a 4X4 layer 
> of hardware cloth
> at the base of the antenna. So the question becomes; when 
> do I reach the
> point at which I am wasting time, wire, money, and wear & 
> tear on my tired,
> fat, old body?

Mike,

With 1/4 wl radials somewhere around 50 is the point where a 
curve representing field strength flattens way out. There 
just is a point where all the earth currents move into the 
low loss radials, and when you reach that point you are 
pretty much all done. Anything more than that simply wastes 
copper, because there is no significant current to move out 
of the lossy dirt.

Unfortunately there really isn't any data to point you to 
with very short radials of varying length. Measuring 
impedance does not work because field strength doesn't 
always follow base resistance changes. Many people have 
measured field strength and found the lack of correlation.

There were two important links given in the recent "radial 
gain" thread.

Brown Lewis and Epstein's data at:
http://k6mhe.com/BLE.html

and N6LF Rudy's data at
www.antennasbyn6lf.com

Unfortunately unless you actually watch the field strength 
change you will never know when you are done. The best 
advice might just be to do as much as you can.

73 Tom