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Author Topic: MY CB GO BOX  (Read 2467 times)

gil

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Re: MY CB GO BOX
« Reply #15 on: November 20, 2017, 05:57:28 PM »
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I will keep you posted!

Please do, thanks!

Gil.

cockpitbob

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Re: MY CB GO BOX
« Reply #16 on: November 20, 2017, 07:52:40 PM »
At a simple level I knew having different polarizations reduces reception, but I never knew any numbers.  Over at antenna-theory.com I found this little gem:  http://www.antenna-theory.com/basics/polarization.php

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In general, for two linearly polarized antennas that are rotated from each other by an angle , the power loss due to this polarization mismatch will be described by the Polarization Loss Factor (PLF):
 
Polarization Loss Factor

Hence, if both antennas have the same polarization, the angle between their radiated E-fields is zero and there is no power loss due to polarization mismatch. If one antenna is vertically polarized and the other is horizontally polarized, the angle is 90 degrees and no power will be transferred.

So now I have a rule of thumb and numbers I can work with.  I love numbers ::) .  I think the equation falls apart around 90degrees because it predicts zero, but in the real world, the polarizations are probably imperfect so even if the antennas were 90.00deg off, some will get through. 

But here's my big take-away.  At 45deg the power transfer is 50%.  That's only 1/2 an S-unit.  You could cant your 4-element Yagi 45deg and its 8dB of gain would only drop to 5dB gain.  You could do fine talking to both repeaters and SSB operators without having to fuss with the antenna.