NVIS Antenna Modifications

A NVIS type we have used at field day the last several years is from a 73 mag in 1959 I think. It is the SGA (Super Gain Antenna).

It is a dipole that is 7 ft off the ground and has a counterpoise directly under the antenna lying on the ground. We usually use three counterpoise spaced at about six feet.

A folded dipole is a better match than the dipole, but we normally feed the dipole with open wire line. The antenna is cut for 40 meters but works well on 20 and 15.

I would be very much interested in seeing how this antenna turns out when modeled.

I believe it has about 9 db gain straight up. ?

Stan AK0B
Ak0b at swbell dot net

Hi Pat..

I built the version of the AS-2259 as described by N6MRX, Dr. Carl O. Jelinek

I found that by replacing the 50 Ohm Coax with a 450 Ohm Feeder and using an ATU at the Ground, it gave me 10-12 db MORE signal on ALL Bands from 160 to 30 Meters.

Next I will try lengthening the wire elements to resonance at 40M and 80M using first the 450 Ohm twin lead then 50 Ohm coax. I plan to feed both with an ATU at the ground.

Vy 73, de OZ3XO - Stig

Hi Pat,
Last year, we assisted WBØDSG, Don, with a simulated RACES emergency at the Telluride airport. I used a 34' section of 14 guage wire approximately 4 1/2 feet off the ground horizontal attached directly to my Icom AH-4 coupler which was mounted on the rear of my SUV, with approximately the same length counterpoise (afterthought) on the ground the oposite direction! Had no problem being heard anywhere in Colorado by anyone listening (State EOC, etc.). We were also lucky that 75 stayed in for the duration of the exercise! I'm going to be experimenting with a new type of antenna utilizing a 22' aluminum telescoping mast with the 3 guywires being part of the antenna with 3 counterpoise wires. This will be loading the aluminum mast at its base and radiating vertically AND inverted 3 legged V with a tuner or coupler.

73
Bill
KØSSI