[Moon-net] Polarity switching - 45 degree steps - Myth or SecretWeapon?

[Earl (Jim) Shaffer, WB9UWA]

Hi Vic.

In the past, I have run a set-up that allows me to RX vertical, horizontal 
or
both 45 degree polarities. It works. I used a 4 position coax switch and 
selected
delay lines in and out and combined outputs to provide + or - 45 degrees.
Each of the 4 positions was driven by a pre-amp with multiple outputs to
have the proper polarities. To calibrate the system, I made an oscillator
driving a dipole rotated in polarity by strings from the ground. This was
located about 50 feet in front of the EME array. The result was that often
a signal that was similar in strength on vertical and horizontal would be 
3db
stronger on a 45 degree polarity. Generally this condition did not hold for 
long
and soon either vertical or horizontal would be better. There may be some 
advantage
during a contest on CW. Linrad would be the optimal utilization of polarity 
control
on RX.  When using JT65, this is probably an uneeded refinement and it may 
be
challenging to select the best polarity then since the signal may not be 
detectable
in real time. Ususally if the signal is detectable in real time, then only 
one polarity will produce
a null. The opposite polarity is then optimal.
When using JT65, I simply reverse the RX polarity between vertical and
horizontal if the signal is not detected right away.

45 degree polarity may be an advantage on 2M perhaps 10 - 15% of the time.
If using CW, consider listening to two receivers, one on vertical and the 
other on horizontal (Stereo or switched).
I have done this using a waterfall display on each receiver and would know 
right away which polarity is best.

73, Jim Shaffer, WB9UWA.




----- Original Message ----- 
From: "Vic Nyman" <nyman at mindspring.com>
To: <moon-net at list-serv.davidv.net>
Sent: Monday, February 18, 2008 4:12 PM
Subject: [Moon-net] Polarity switching - 45 degree steps - Myth or 
SecretWeapon?


>>> Subject: [Moon-net] Polarity switching - 45 degree steps - Thanks
>> ...
>>> Thanks to everyone who replied both publicly and privately to my
>>> request.  It appears that SM5BSZ Leif's Switchless Combiner is the
>>> simplest path to 45 degree switching.
>>>
>>> I would be very interested in hearing about practical experiences
>>> using this method. If you have successfully (or unsuccessfully, HI)
>>> used this approach, would you mind contacting me off the list
>> ...
>>
>> I suspect I am not the only one here who would also be interested in
>> hearing about practical experiences with this method of polarity
>> switching.   Unless there is a wave of protest, I think replies *to
>> the
>> list* would be of interest and may benefit many of us who frequent
>> this
>> list.
>>
>> I make this remark as a polite comment and not a rebuke.
>>
>> JoeC, K3FMA
>>
>
> Joe - no worries on the comment.
>
> So far, no one has responded with any experiences. I am beginning to
> wonder if 45 degree switching is a Myth or a secret EME weapon?  :-)
>
> Has anyone had any good or bad experiences using 45 degree switching?
>
> Thanks,   Vic - K4UCY
>
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