Re: [amsat-bb] UO-14 Passes

[tlang@xxxxxxxxxxxxxxxxxxxx (Tony Langdon)]

Hello Mike.

14 Aug 00 06:47, you wrote to Norm McMillan:

 MG> The reason the ARROW antenna users have such good luck is they develop
 MG> a technique where they twist the antenna to match the downlink
 MG> polarity of the satellite, which can change during a pass.

I've found this alone can contribute several dB to the fade margin for the
link.  The polarisation of the satellite varies considerably during the course
of a pass, and it's different from pass to pass.  I've seen passes where
everything is pretty much rock stead, and others where one has to do a slow
pirouette with the beam to keep a good signal! :-)

 MG> I have tried eggbeater antennas for satellite operation,  and unless
 MG> it happens to be a high elevation pass, the results are not
 MG> satisfying.  Jerry Brown, K5OE studied the engineering of these
 MG> antennas and has come up with a steerable version he calls the TPM.
 MG> He tilts the antenna so more of the pass is detected by the major lobe
 MG> of the antenna.

I use a variant of Jerry's design for the 70cm section of my portable beam.

 MG> I believe you will find a gain rubber ducky (not the stock stubby) on
 MG> a handheld, waved about to find the right orientation will beat the
 MG> egg whites out of the egg beater.  I can hear UO-14 on any of several
 MG> handheld devices, with a gain vertical, in the middle of my wood
 MG> framed ranch home.

A 1/2 wave rubber duck on 70 will do a fair job of receiving UO-14 on most
passes.  I used to use one when UO-14 first fired up in FM.

Tony

.. Windows: Proof that Microsoft has a roomful of monkeys with keyboards.
--
|Fidonet:  Tony Langdon 3:633/284.18
|Internet: tlang@freeway.apana.org.au
|
| Standard disclaimer: The views of this user are strictly his own.


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