[BC] The Future / Signal

[Harold Hallikainen]

I'd guess these dishes have similar horizontal and vertical beamwidths, so
my theory on that doesn't appear to be correct. Thanks for the additional
info!

Harold


> These were 4 foot Mark gridded dishes...properly tilted to look at each
> other(at night wuth a telescope you could see the receive site),
> -D
>
> ------ Original Message ------
> Received: Mon, 04 Dec 2006 09:27:29 PM EST
> From: "Glen Kippel" <glen.kippel at gmail.com>
> To: "Broadcasters' Mailing List" <broadcast at radiolists.net>
> Subject: Re: [BC] The Future / Signal
>
> As Harold so astutely noted, the horizontal beamwidth of a Scala
> Paraflector
> is indeed quite broad if it is mounted on its side, i.e. horizontal
> polarisation.  I don't even know if such an attitude would be permissible
> in
> this area, with 2 and sometimes 3 stations on every STL channel.  Some 14
> years ago, I was told that 6-foot or larger dishes would be required.
> Existing stations using Paraflectors and even Miniflectors are
> grandfathered
> in, but it would be hard to get those approved now.
>
> On 12/4/06, Harold Hallikainen <harold at hallikainen.com> wrote:
>>
>>
>> > All I know is that I once ad a 950 link that ran over the LA basin.
>> With
>> > Hpol,
>> > on a hot summer day you could watch the signal vary from over 2 mv/m
>> to
>> > ZERO
>> > (IE: station off the air!). It would stay at 2 mv all night.
>> >
>> > Went to vertical and the problem DISAPPEARED!!
>> >
>> > -D
>>
>>
>> Instead of polarization is this, perhaps, difference in beamwidth
>> between
>> "horizontal" and "vertical" on the antenna? If this was a Paraflector
>> PR450-U mounted for vertical polarization, I think they had a fairly
>> narrow "horizontal" beamwidth, but a wide "vertical" beamwidth. Rotating
>> the antenna 90 degrees swapped these beamwidths. If the air at a
>> particular elevation is one temperature and the air above it is another,
>> I
>> think a signal heading from a lower elevation to a higher would be bent
>> "up or down" instead of "east or west" as it passed through the
>> boundary.
>> If you have a narrow vertical beamwidth, it may bend up or down enough
>> to
>> miss the receive antenna.
>>
>> So, is it possible that the issue was not polarization, but, instead,
>> beamwidth?
>>
>> Harold
>>
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