Correct, Jim. The FAA radars use circular polarization to attenuate weather
returns.
The WSR-88D radars used by the NWS originally used linear horizontal
polarization because raindrops are essentially hamburger shaped. These radars
now also include vertical polarization because the two, together, yield
information about the hydrometeors.
Apologies, this way OT.
Kim N5OP
"People that make music together cannot be enemies, at least as long as the
music lasts." -- Paul Hindemith
> On Nov 23, 2014, at 20:51, James Duffer <dufferjames@hotmail.com> wrote:
>
> As I recall when we went to "circular" polarization the returns from weather
> was reduced because of the fact the returns were of the opposite circular
> polarization. (eg. transmit right hand circular returns reflected from
> "round" droplets would be left hand circular), and that fact caused
> additional reduction of signal thru the polarizer. Since I have been retired
> since 1994 from FAA (radar watchstander) my memory begins to fade.
>
> Jim WD4AIR
>
>> From: cw_de_n5op@sbcglobal.net
>> Date: Sun, 23 Nov 2014 19:26:12 -0700
>> To: k9yc@arrl.net; tentec@contesting.com
>> Subject: Re: [TenTec] OT: K9YC on Vertical or Horizontal / Heights
>>
>> Arggghh! I despise "auto-wrong!" Meant *circular polarization.* Linearly
>> polarized radiation becomes circular after reflection from the ionosphere
>> due to Earth's magnetic field.
>>
>> I dunno what cochlear polarization is, either.
>>
>> Kim N5OP
>>
>> "People that make music together cannot be enemies, at least as long as the
>> music lasts." -- Paul Hindemith
>>
>>>> On Nov 23, 2014, at 16:26, Jim Brown <k9yc@audiosystemsgroup.com> wrote:
>>>>
>>>> On Sun,11/23/2014 3:14 PM, Kim Elmore wrote:
>>>> If you could phase these so as to generate and receive cochlear
>>>> polarization (90 deg), either LH or RH, you might see a very big increase
>>>> (I think as much as 6 dB) in rx signal strength from what I've read. That
>>>> would be pretty cool.
>>>
>>> I've never heard of cochlear polarization. These dipoles are horizontal, at
>>> right angles in the horizontal plane. Driving both of them with a suitable
>>> phasing network would result in a circular pattern, at the expense of 3dB
>>> of gain. Far better switch them and keep the 3 dB.
>>>
>>> 73, Jim K9YC
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