[BC] High Gain vs Low Gain Antennas

[Thomas G. Osenkowsky]

This is exactly why a station needs to examine ALL
factors in the transmission system. Careful choice of
transmitter site, HAAT (tower height), TPO vs Gain,
Beam Tilt, Null Fill, tower face and antenna mounting.

ALL these play an important part in delivering an
optimum signal to the listener. I had one client who
did everything right....or so it would seem. An 850'
tower, pole mounted antenna. They were a Class B
non-D. A strongly desired market about 20 miles away
had a very bad signal. Plenty of RF, just severe multipath.
All I had to do was pull up a topo map and see solid brown
to the immediate West of the city. A tall mountain range.
A great reflector. Atop the mountain were two towers
that had the TV antennas on them. I recommended doing
a pattern study to determine the antenna mount that would
provide the *least* signal toward the West and put a
booster on one of the TV towers to feed that city.

The first step is to define where you want to serve. The
next steps are to consider ALL factors that affect the signal
you will deliver there.

Tom Osenkowsky, CPBE

> What really matters is the field strength at the receiver.
> Since received field strength is a function of power times antenna
> gain, it is much more efficient to use the latter.  The hard part is to
come
> up with an appropriate balance between the two.  Also, because of
> inverse-square law, proximity of the transmitting system to the receiving
> system is important, too.  If you are serving a market that is surrounded
by
> a hundred miles of nothing, it doesn't make sense to put a signal out
there
> at the expense of the populated area.