Fi> Hi. As a part-time station designer, I have been asked to recommend
Fi> a low-band receiving antenna for a location that has unusually good
Fi> ground; i.e. a salt marsh. I have heard many times (I think it is in
Fi> ON4UN's book) that beverages don't work so well over spectacular
Fi> grounds, as it is the ground losses that actually refract incoming
Fi> waves to produce a horizontal component parallel to a beverage
Fi> conductor.
Fi> -Tony, K1KP, fisher@hp-and.an.hp.com
Tony, you've got it wrong! ON4UN says just the OPPOSITE in the 2nd edition
of LOW-BAND DXing. On page 7-1, he describes how at VLF, where the signals
are all GROUND WAVE (zero wave angle), the antenna depends on poor ground
conductivity to tilt the incoming wave. He goes on to say that on the low
amateur bands, the signals are predominantly SKY WAVE, where the wave angle
of the incoming wave itself (0 to 50 degrees) is responsible for inducing
voltage in the antenna. The only effect of ground on Beverage performance
is that the OUTPUT drops over good ground vs. poor or average ground but
the low angle performance improves somewhat. Over saltwater, however, a
Beverage is no good since the low angle performance is very poor. ON4UN
describes his QTH as being over very good ground and we all know how his
Beverages perform!
The EWE antenna may still be a worthwhile antenna since it requires only a
fraction of the space required for a Beverage.
73 Bill
N6CQ@paonline.com
|