[GreenKeys] RF Polarity

[Ralph Mowery]

----- Original Message ----- 
From: "Larry Tighe" <larryradio at worldnet.att.net>
To: <greenKeys at mailman.qth.net>
Sent: Saturday, September 02, 2006 12:30 PM
Subject: [GreenKeys] RF Polarity


>A bit off topic but maybe of interest.....
>
> I was using 51.5MHz  last nite.  I was horizontally polarized with a 3 
> element beam using a military RT-524.  The other station was vertically 
> polarized.  Our distance was about 50 miles.
>
> Question to the RF'ers on the list....does cross polarization have much 
> effect at 51 MHz?
>
> Lar
> www.antiquetelephone.com

----- Original Message ----- 
From: "Larry Tighe" <larryradio at worldnet.att.net>
To: <greenKeys at mailman.qth.net>
Sent: Saturday, September 02, 2006 12:30 PM
Subject: [GreenKeys] RF Polarity


>A bit off topic but maybe of interest.....
>
> I was using 51.5MHz  last nite.  I was horizontally polarized with a 3 
> element beam using a military RT-524.  The other station was vertically 
> polarized.  Our distance was about 50 miles.
>
> Question to the RF'ers on the list....does cross polarization have much 
> effect at 51 MHz?
>
> Lar
> www.antiquetelephone.com
>
Yes, it can have a very large effect.  Around 15 to 20 dB in actual usage. 
Theory says about 20 db.  From actual usage I can tell you that it will have 
a very large effect if using ground wave.  If the signal reflects off the 
ionosphere then the signal will not  usually be that much differant.  If the 
signals arrive at 45 deg or less to the antenna , the loss is only 3 db or 
less.  While I am sure the effect would be the same on all frequencies, 
below 20 mhz or so the signal is usually propogated by skywave and the 
ionosphere will usually rotate the signal so it will not stay exectally 
vertical or horizontal so that much effect is not normally observed.

de KU4PT