[Antennas] Need a little help
Dave Shrader
[email protected]
2002年4月14日 20:31:01 -0400
Mike,
I've used the Tennadyne T8 at 40 feet and am absolutely 100% pleased
with it. There is an excellent reason why the USAF and US State Dept.
use LPs ... they work great! I'm a retired USAF contractor. I'm going to
70 feet this summer as optimum.
EZNEC (demo) at 70 feet gives some relative elevation solutions for 20
meters. No skywarmers on 15 and 10.
You will have multiple forward lobes and a skywarmer on 17 and 12
meters. But significant over the horizon lobes for VG performance.
20 meter summary
70 feet gives 2 lobes in the forward direction, a low angle and an
intermediate angle.
35 feet gives 1 lobe but at a intermediate angle.
60 feet gives 2 lobes, 1 low and the second a skywarmer.
90 feet gives 3 lobes, 1 low angle, 1 intermediate and 1 skywarmer.
70 feet puts the energy over the horizon not overhead.
Note: EZNEC is a computer program that calculates antenna performance.
The effect of ground is approximated and the effect of nearby objects is
not modeled. But, it gives a visual on how the antenna SHOULD/COULD
perform [well maybe <grin>].
Michael Taylor wrote:
> I am wondering if the gain in performance justifies going from 60 to 90 feet. The antenna covers 13-30 MHz and the 40 meter band.
>> AL1N