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Whip Antennas (was Re: AO-7 requirements)





At 11:01 PM 2/14/2004 -0500, you wrote:
>Emil, I'm guessing you haven't ever tried this. The 5/8 wave stinks for
>mobile satellite work due to it's pattern being focused on the horizon. It's
>not enough gain on the horizon to work, and too big of a null overhead to
>work well there (primarily as a receive antenna, you can get up to the bird
>on just about anything). A single 1/4 wave whip on 2m works great on the
>uplink, and the same antenna performs ok as a 3/4 wave on the 435 downlink,
>with even a little gain overhead.

Actually I have, and I agree that the 1/4 wave works OK on transmit, but 
not on receive.  And the 5/8 wave only needs to be slightly inclined (about 
15-25 degrees from vertical) to overcome the null problem.

In the original post AL7EB wrote "Leo operation may have to be done mobile 
using mag-mounted whips?  Not sure how good that approach is."

So I stand by my original statement - an 18" whip won't pick up SO-50 and 
may not pick up AO-27.  Echo perhaps (I've worked UO-14 on a 18" whip while 
driving) but not SO-50. Holding a yagi out the window is much better, but 
you shouldn't try that while driving.

One other thing - he also indicated that "Ham radio is secondary to the 
trip objective so we will see.  It is mostly for entertainment for the 
relief driver (me)!"  Considering his route, when he gets out in the 
boonies the extra gain will come in handy for hitting more distant simplex 
stations and repeaters.

73,

Emily


---------------------------------
W0EEC - CM87tm
AMSAT Area Coordinator - San Francisco Bay Area
http://www.projectoscar.net    http://www.PlanetEmily.com 
http://www.experthams.net/ao7

Help Launch Echo - http://www.amsat.org/amsat/sats/echo/index.html
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