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RE: TH-F6 and UHF SSB



I modeled a 19" vertical using NEC and it does seem to workout pretty
well for satellite use.
The main lobe is at about 50 deg. and looks pretty broad. The only down
side was the deep null straight up (from around 80 deg. or so). Not much
gain but it doesn't require a rotator either.
I'll have to try it sometime.
Steve .. AI7W

-----Original Message-----
From: John Mock [mailto:kd6pag@qsl.net]
Sent: Tuesday, February 26, 2002 05:38
To: amsat-bb@AMSAT.Org; jepsen_st@mindspring.com
Subject: re: [amsat-bb] TH-F6 and UHF SSB


    > I don't think this is correct. A 1/4 wave 2 meter antenna (about 19")
    > works as a 3/4 wave antenna on 70cm. Although a 3/4 wave antenna has a
    > fairly good match to 50 ohms (unlike a 5/8 wave that requires a
matching
    > network)it doesn't have a very good radiation pattern for land mobile
    > use. It may very well out perform a 'rubber duck' but it won't perform
like
    > a 5/8 wave antenna.

You're right, and indeed, my van has a 2m 1/4 wave tuned for optimized
for good SWR in the 70cm on satellite sub-band it for that reason indeed.
It's definitely a poor performer for repeaters, but it's just the right
thing for the J-FM birds.  And unlike the rubber ducks that i mentioned
earlier, it doesn't do so badly in most urbanized areas (my own area
excepted due to an badly coordinated[?] ATV station).

				-- KD6PAG

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