QFH - TRUELY OMNI DIRECTIONAL ANTENNA

[Mrs T Cooper]

If you are looking for a perfectly omni directional antenna for your ATC feed, take a look at the 'QFH' antenna.  Was designed by NASA I believe, and is used on the space crafts.

I use it for reception of the NOAA orbitting weather satelites, where an antenna that is omni in elevation as well as azimuth is essential.  In this case it is cut for 137.5 MHz (centre of weather sat band 137/138 MHz)....but on the following website there is a calculator for entering any VHF frequency, which will then read out all the dims required.

http://jcoppens.com/ant/qfh/index.en.php

On there you will also find pictures of my particular QFH antenna used at this location in the UK, and built out of 8mm microbore central heating copper pipe, a length of 1.5 inch waste water pipe, qty 8X 90deg 8mm copper angles, and a 5amp mains electricity junction box.

Exceptionally good results, with no nulls what so ever, regardless of azimuth or elevation of the satelite (aircraft?) path across the sky.

Far better than any expensive commercial Discone antenna.

73

Nev (G3LMO)

[dave]

Hi Nev-

The QFH is perfect for reception of aircraft, but doesn't it have some significant nulls on the horizon?  That would make it less than ideal for those on the fringe of ground transmitter range who might be trying to hear both controllers and planes.

OTOH, for those close to ground transmitters, where there is more link margin, this looks like a great idea.

-Dave