[BC] The Future

[Mark Humphrey]

On 12/2/06, Robert Meuser <Robertm at broadcast.net> wrote:
>
> I think multiplex sites will work with much closer channel spacing
> thanks to totally different technology.

It's already practical to multiplex FM signals at less than 800 kHz
spacing by installing two master antenna systems, so that the closest
channels can be fed into different combiners, reducing loss while
increasing isolation.

An example in Germany is the Berlin-Alexanderplatz "Fernsehturm",
where stations on 93.1 and 94.3 use the lower "UKW" antenna, with a
co-located 93.6 on the upper antenna:

http://www.d-no.de/fs-turm.htm

Of course, the "space combining" schemes for FM IBOC, using separate
antennas for analog and digital, work on the same principle.

I manage a tower site in the western suburbs of Philadelphia where the
rent is based on the length, diameter, and number of transmission
lines, so everyone has an incentive to minimize tower loading.  Some
of my tenants who are running trunking systems have come up with some
clever combining schemes like this, so they can keep the number of
antennas as low as possible.

Mark