[Moon-net] Orthogonal polarization???

[Edward Cole]

At 04:42 PM 1/11/2008, Leif Asbrink wrote:
>Hi Bill,
>
> > "This antenna is remarkable in that the stacking gain
> > for four antennas can exceed 6 dB. Even using a single
> > Horizontal/Vertical relay, You have a moonbounce
> > package that can outperform larger, linear arrays.
> > Additional relay switching providing 4 different types
> > of discrete receiving polarizations: Horizontal,
> > Vertical, Right Orthogonal, and left Orthogonal bring
> > you near peak on all signals. Losses from spatial
> > polarity and Faraday rotation virtually disappear. EME
> > reliability approaches 100%."
>
>Never heard of Right Orthogonal, and left Orthogonal,
>maybe they mean right and left circular...
>
>There is some info about cross yagis here.
>http://www.sm5bsz.com/polarity/polroot.htm
>
>The high power five relay solution on "simple switching" link
>is the system I was using for nearly 10 years on the TX side.
>It allows H,V,+45 linear,-45 linear, left circular and right
>circular.
>
>On the receive side I used continuos polarization rotation
>with schottky diodes and a varicap phase shifter for several
>years, but after that I used stereo receivers which is the
>ultimate solution with zero faraday loss always (on the Rx
>side.)
>
>73
>
>Leif  /  SM5BSZ

Being one who runs four M2 2m-xpol-20's with a simple H/V switching 
arrangement, I can attest to how well they work.  I do not know how 
one exceeds 6-dB stacking gain but they do hear very well.  With just 
the ability to switch H/V, I have completed 80% more of my eme 
contacts that would have ended in failure, otherwise.  Choosing 
cross-yagis when I began setting up my eme system in 1998 was a very 
good choice for someone installing a small eme array (four 3WL yagis).

I did use two phase-shifters with two preamps for a continuous 
polarity rotation on RX for awhile until losing one preamp.  That 
preamp had been repaired about five times (mgf-1302 replaced) so that 
the pcb ckt was shot and not reparable, again.  I decided to revert 
to the simple H/V system using four coax relays for independent TX 
and RX polarity switching.  This does result in sometimes having as 
much as 3-dB degradation, but it is simple.

My next step will be to use two receivers for full polarity rotation 
in sw under Linrad.  I am hoping someone will figure how to utilize 
two SDR-IQ with two preamps and 144/28 converters to accomplish 
this.  It may require a specially designed dual-channel SDR with 
common clock and synchronized data interfacing.  I know Leif has 
already a receiver that accomplishes this.

My guess that "orthogonal" means +45 and -45 degree linear 
polarization angles.  Circular pol would not make any sense for 
current use on 2m-eme as you would always suffer 3-dB polarity 
mismatch loss.  Leif shows how to set up switching to accomplish 
this.  I will not change my TX system beyond simple H/V and 
concentrate on receiver improvements.

I am currently working on my 8877 PA, having finished the control 
panel (HV testing next); then I will finish the RF compartment.  At 
the same time I am upgrading my computer system to take advantage of 
the Linrad/MAP65 sw system using two computers.  Has anyone done this 
using the SDR-IQ to feed windows Linrad?  I will eventually go to 
Linux-based Linrad.

I will be QRV briefly on 20Jan after 0500.  I will not be on the Moon 
until the DUBUS/REF Digital Contest so I can concentrate my efforts 
on the 8877PA.


73,
Ed - KL7UW
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  BP40IQ   50-MHz - 10-GHz   www.kl7uw.com
144-EME: FT-847, mgf-1801, 4x-xpol-20, 185w
DUBUS Magazine USA Rep dubususa at hotmail.com
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