M2 makes one, and I think Gulf Alpha antennas has one.
73, Jim KQ6EA
On 05/14/2013 02:04 AM, Rolf Krogstad wrote:
Thanks, Bob.
Is there a commercial yagi available for 435 MHz which is R-L switchable?
Rolf NR0T
On Mon, May 13, 2013 at 8:21 PM, Bob- W7LRD <[email protected]> wrote:
the helix is a nice antenna...however...once wound for either RHCP or LHCP
there's no going back. So switching from R to L or L to R is out of the
question. Unless of course the chosen polarity is always compatible with
the satellite in use. Unless you have L and a R helix and switch between
them, that can get a "little" involved. Many times it is
very convenient to be able to switch between L or R during a pass, at times
it can make the contact happen. This is of course is easy with a L/R CP
yagi. I have used a helix for L band (1.2ghz ) as well as feeds for a
2.4ghz dish. They are a fine antenna with a fair amount of bandwidth. For
a 16+ turn helix I have used stainless steel "U" channel for the center
support. If Clair, VE3NPC is listening, he's the resident helix guy.
Just my opinion, your mileage may differ.
73 Bob W7LRD
Seattle
------------------------------
*From: *"Rolf Krogstad" <[email protected]>
*To: *[email protected]
*Sent: *Monday, May 13, 2013 9:22:57 AM
*Subject: *[amsat-bb] Helical Antenna on 70 cm
I am new to satellites and new to the design requirements for UHF and am
looking for advice.
I am looking to build a Helical antenna for the 70cm Band. I am
considering the plans for such an antenna from the 2010 edition of the ARRL
Satellite Handbook. The plans call for a 235 cm (7' 8") long, 2.5 cm (1")
diameter center support made of either a wooden dowel which has been
treated or a fiberglass tube. It also requires multiple 7.6 cm (3")
spacers for the helical element.
My question is would fiberglass rods made of "Isophthlic Polyester Resin"
be a good choice of material at UHF frequencies?
I hesitate to use treated wood because I plan to mount this on the top of a
15 meter high tower and it isn't very accessible.
Thanks
Rolf NR0T
[EN34]
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_______________________________________________
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Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
_______________________________________________
Sent via [email protected]. Opinions expressed are those of the author.
Not an AMSAT-NA member? Join now to support the amateur satellite program!
Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
