[opendtv] Re: MIMO

Bert,
I hate it when you make me think and recall things I already know and which
I have overlooked in my ramblings! IIRC, the FCC specification for CP is
"right hand" circular.

John, the phase shift is generally provided by adjusting cable lengths in
panel antenna configurations and by adjusting "slot" positions in coaxial or
waveguide type antennas. Horizontal directionality is determined by the
placement of radiators around the mast and can create many patterns,
horizontally and vertically, by phase shifting selected radiators.

> -----Original Message-----
> From: opendtv-bounce@xxxxxxxxxxxxx
> [mailto:opendtv-bounce@xxxxxxxxxxxxx]On Behalf Of John Shutt
> Sent: Tuesday, May 01, 2007 6:24 AM
> To: OpenDTV
> Subject: [opendtv] Re: MIMO
>
>
> Bert,
>
> I take that back.  We use a Dielectric TUF 04-12/48 broadband UHF panel
> antenna, which is four columns of 12 panels each, facing in four compass
> points.
>
> You can order these antennas with many different patterns other than
> omnidirectional, and to do that you must need some sort of delay
> line to get
> the phase cancellation in differing directions.
>
> I will retract what I wrote and instead keep my mouth shut on
> matters that I
> do not know about.
>
> John
>
> ----- Original Message -----
> From: "John Shutt" <shuttj@xxxxxxxxx>
>
>
> > Bert,
> >
> > Sorry, I wasn't clear.  It is possible just as you outline, but
> it is not
> > practical to have a 1/4 wavelength delay line at low UHF that can be
> > mounted 1000' in the air and is capable of handling 40KW, which
> would be
> > necessary to feed one of the polarities.
>
>
>
>
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