[opendtv] Re: MIMO
- From: "Dale Kelly" <dalekelly@xxxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Mon, 30 Apr 2007 16:04:05 -0700
You are correct of course, true CP requires a helical antenna or something
with similar properties. I was simply speaking to broadcasting technology
> -----Original Message-----
> From: opendtv-bounce@xxxxxxxxxxxxx
> [mailto:opendtv-bounce@xxxxxxxxxxxxx]On Behalf Of John Shutt
> Sent: Monday, April 30, 2007 3:46 PM
> To: opendtv@xxxxxxxxxxxxx
> Subject: [opendtv] Re: MIMO
>
>
> Dale,
>
> How is it possible to have a circularly polarized omnidirectional signal?
> You can have a dual horizontal and vertical polarized high power UHF
> television transmission antenna, which is what passes for "CP" in the
> broadcast world, (or if the power ratio is not 1:1 it is called
> "elliptical"
> as you correctly pointed out,) but you never see a spec in the
> Dielectric or
> Andrews (R.I.P) catalogs for a "Left Hand" or "Right Hand" circular
> polarization of their UHF antennas. They just list the horizontal to
> vertical ratio.
>
> DBS uses a true circular polarization, as does some forms of
> radar, but in
> both cases the radiation is highly directional.
>
> John
>
> ----- Original Message -----
> From: "Dale Kelly" <dalekelly@xxxxxxxxxxx>
>
> >
> > This is actually known as elliptical polarization. Many antenna do use a
> > degree of elliptical Pol. and off handedly it is sometimes called CP.
> > However, there are also a number of true CP installations, though I
> > believe
> > that elliptical is clearly in the majority and they do also improve
> > reception but to a lesser degree. It's an economic trade off.
>
>
>
>
>
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