[Antennas] Repeater Antenna

2002年5月03日 16:13:56 -0700

The 3/4 coverage angle you mention implies that the repeater is at one edge
of the intended coverage area. My first choice would be a Sinclair SRL-222
offset dual dipole unit. It is rugged, rated for 120 mph winds, has 6 dBd
gain, and costs about 400ドル.
The Celwave/RFS antennas are excellent omni-directional units and are the
ones chosen by Motorola. The PD-220-2 "Super Stationmaster" antenna is
designed to cover 142-150 MHz, is rated for 100 mph winds, has 5.25 dBd
gain, and costs about 650ドル. The PD-620-2 covers the same band but is rated
for 175 mph winds, same gain, and costs about 1500ドル.
Before you order any antenna with downtilt, consider whether the loss of
gain and bandwidth are worth the considerable additional cost. Moreover,
don't get downtilt unless you really, absolutely, positively need it. Most
antenna makers, including Celwave, will make downtilt antennas only for a
specific frequency and on special order. In my experience, primarily
limited to Central California, relatively few installations warrant a
downtilt antenna.
Whichever antenna you select, use at least 1/2-inch Heliax as feedline. For
the feedline distance you mentioned, RG-8 type (even 9913) has a significant
loss.
73, Eric Lemmon WB6FLY
[email protected] wrote:
> Gentlemen: After a little testing of our two meter repeater antenna, it
> became obvious that it had gone south. No obvious burns or any
> indication of structural failure, but SWR had gone way high. Therefore,
> we need to select a replacement.
>>>> which antenna would you choose and why? We have severe winds at the
> site, with modest ice loading. The support is about 50' above ground
> (metal windmill tower) and the ground rolls off gently in the 270 degree
> area of intended coverage. We run a GE MastrII transceiver, running
> about 30 watts out of a 4 cavity duplexer. The previous stacked
> collinear antenna covered the area adequately, but we are looking for
> the best commercial antenna (within reason price wise) for the site.
> You may reply to me directly, or thru the reflector, as you see fit.
>>>> YOUR IDEAS AND RECOMMENDATIONS, PLEASE?
>>>>>> Randy
>> AC7NJ
>> --- StripMime Report -- processed MIME parts ---
> multipart/related
> multipart/alternative
> text/plain (text body -- kept)
> text/html
> image/jpeg
> image/gif
> The reason this message is shown is because the post was in HTML
> or had an attachment. Attachments are not allowed.
> Please post in Plain-Text only.---
> - - -
>> Your moderator for this list is:
> Larry Wilson KE1HZ [email protected]
> _______________________________________________
> Antennas mailing list
> [email protected]
> http://mailman.qth.net/mailman/listinfo/antennas