I measured the military AT-197 UHF mil air Discone dimensions primarily for ”jersymilair” but posted here for everyone’s benefit. The AT-197 skirt length (if the skirt continued to a sharp point at the top) is 19 1/2”. Actual skirt element length is 18”. Top hat diameter is 13 1/2 “. The gap between the skirt and top hat is a very complex shape on this antenna and hard to measure. I would estimate 1/2 to 3/4 “ and this will have an effect on the match. Even though it measures very good down to 175MHz on a network analyzer, this antenna is designed for best performance in the 225-400MHz range with a low radiation angle, that’s why it hovers toward the low frequency of it’s useable band width. This antenna will be useful up to about 1400MHz but the radiation will get a bit squirrelly at the higher end.
prcguy
prcguy
