[HCARC] Curious question

[Kerry Sandstrom]

Gary,

It would act as a reflector.  Depending on the height of the antenna above 
it (in wavelengths) it would either cause a maximum or a minimum straight 
up.  With NVIS, that is what you have.  the ground acts as a reflector and 
at low frequencies most of the radiation from a low horizontally polarized 
dipole goes straight up.  If the antenna is an even number of quarter waves 
above the ground, there will be a null straight up.  If it is an odd number 
of quarter waves above the ground there will be a peak.  For intermediate 
heights, it will be in between a peak and a null.  The gain or loss (peak or 
null) will depend on how close to a perfect ground the mat is.

Because you have a large metal object close to the antenna, it will also 
change the impedance of the antenna.

Kerry