QFH Antenna

Discuss commercial and home made antennas.
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njrusty
Posts: 17
Joined: Sun Jun 30, 2019 12:28 pm

QFH Antenna

Post by njrusty » Wed Sep 04, 2019 3:20 pm

Need to build a QFH coax antenna and cannot determine if the cable running from the 'top' of the horizontal PVC cross is a single piece that runs from top, to the bottom PVC and them back up to the top for one loop, then another cable repeats from top to bottom for the other loop. I know they connect to the feeder cable at top, but I cannot determine if these 2 runs are 2 single lengths of cable.

snn47
Posts: 200
Joined: Tue Dec 27, 2016 11:00 pm

Re: QFH Antenna

Post by snn47 » Thu Sep 05, 2019 5:07 pm

Assuming that you are looking for receiving 137 MHz, did you try searching? Have you checked these pictures https://www.qsl.net/l/lu7did//docs/NOAA ... LU2HAM.pdf ?

darwin-t
Posts: 3
Joined: Wed Jan 15, 2020 2:02 am

Re: QFH Antenna

Post by darwin-t » Tue Jan 28, 2020 4:33 pm

Yes, there are two loops. Both start at the top, go through the bottom and back up to the top.

Arlo
Posts: 4
Joined: Sat Jan 25, 2020 10:34 pm

Re: QFH Antenna

Post by Arlo » Thu Jan 30, 2020 5:47 am

Yes. 2 loops on the bottom. Using the short design QFH for NOAA 137 mHz sats.
Able to grab nice signals all the way to 5 degrees H-H.
Mine is made of 1/2" CATV hardline. Used my RSP2 with the internal LNA for a few years now. Just got a nooelec lana today with a pack of sma fittings. Cant wait to grab a few passes.
Just remember that the antenna is a dead short so make sure you don't turn on Bias T for that port on your SDR if you're not using an external lna.
Also it works pretty good out of band below FM broadcast up to at least the upper end of 2 meters.
Good luck! Don't forget the few wraps of cable for a balun.

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