[IRCA] TIS coverage

[AM-DXer@xxxxxxxxx (Patrick Griffith, N0NNK / WPE9HVW)]

Keep in mind that most TIS stations are designed for short distance
operation. Most TIS stations have a very minimal ground system that is
mostly for static/lightning dissipation rather than for counterpoise
purposes. I have inspected well over 100 TIS installations up close and
only a couple had efficient ground systems. Most of the pole mount
antennas have only a simple ground rod at the base of the pole. I have
also inspected five TIS stations using the big Valcom antennas. Only one
of them had an actual counterpoise. The two at D/FW Airport each had
only a single chemically enhanced ground rod. Interestingly, the TIS
stations with the best signals seem to be the roof mounted ones that
either use an actual ground plane laid out on the roof, or the metal
roof support beams, or an actual metal roof as the counterpoise. The
presence of a counterpoise combined with the height of the roof mount
units seems to give them superior coverage.

Patrick Griffith, Westminster CO
Broadcast Technician
NRC Broadcasting - Denver
http://community.webtv.net/N0NNK/
http://community.webtv.net/AM-DXer/

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