Topband: SERIOUS coax choke

[K9AY]

First, I'll assume that you have a transformer with separate primary and 
secondary windings, with separate grounds. This provides common-mode 
isolation between antenna and feedline.

Re-radiation from the feedline into the RX antenna is another matter. If 
your feedline is buried, it's shielded by the earth and all is well. If the 
feedline is elevated above ground it is an efficient receive antenna and can 
contribute significant re-radiation.

In between is your feedline lying on the ground. Here in the agricultural 
Midwest, on-ground is nearly as good as buried. I suspect it's different in 
the desert and other low-conductivity locations. I usually drop two 
Beverages off their support posts when I am not active, to keep the deer 
from getting tangled in them. These two are insulated wire, so I can use 
them as BoG. On bare or rough cultivated ground, the signal strength is 20+ 
dB lower than the normal 36-in. height. It takes extra preamp gain, but they 
work OK as BoG. When these antennas are Beverage-on-snow (BoS) or draped 
across corn stubble (BoCS), signal levels are noticeably higher than BoG. 
Even a small height makes a difference, so I recommend keeping those 
feedlines buried or smack dab on the ground.

73, Gary
K9AY