[Elecraft] Home made Sigma-GT5 & KRC2 or SGC?

Ron D'Eau Claire [email protected]
Mon Mar 22 11:50:15 2004


Vic wrote:

You are right that the takeoff angle of the radiation from the vertical 
element is not dependent on the radials, but if the current in the 
radials is unbalanced, THEY radiate.  That's why a ground plane should 
have at least two radials, and they should be as symmetrical as possible.

-- 

Sort of an un-inverted L (the "inverted" kind has the bend up at the top).
DeMaw had a version in his antenna books for some time using a vertical
aluminum tube radiator sitting in a bottle for a base insulator on the roof
(as high as possible) and one horizontal wire the same length. He fed it
with open wire as a typical doublet. 

DeMaw reported that 33 foot radiators (66 feet total) did okay on 3.5 MHz
and up, based on the "rule of thumb" that the "gain" of a doublet didn't
really plummet until the radiator was less than 1/8 wave long. Of course it
was a full half wave on 7 MHz. In the higher bands above 14 MHz that
vertical radiator would start showing high angle lobes while the horizontal
radiator - assuming it's at least 25 feet or so above the ground - would
start showing good low angle horizontally-polarized radiation.

Ron AC7AC