NEC-LIST: MF fading zone

Hi

I currently use NEC-WIN Pro to analyze the performance of Conical
monopole antennas used for GMDSS A2 coverage (Global Maritime Distress
and Safety System at 2182 kHz)

An MF groundwave antenna can be said to produce a night fading zone
around a point at where the midnight median skywave signal equals the
groundwave signal (say measured out of a reference short receive
vertical monopole). This is entirely a function of VRP and ray
geometry and is independent of power, and absolute signal levels.

I need to determine whether the range to such a point generated by
such an antenna installed adjacent to the shoreline would increase or
decrease if it were moved inland say 1 or 2 kM,

ie does the drop in skywave/ seagain exceed the drop in groundwave ?

If the seagain drops more than the groundwave, then the ideal location
would be slightly inland and it would be useful to be able to
determine the optimum amount.

Regards

Phil Ede
Received on Wed Dec 09 1998 - 10:32:20 EST