[TenTec] [Sorta OT]: Does terrain affect HF radiation patterns?

[Stuart Rohre]

Certainly near by terrain affects your station antenna pattern, in the 
case of obscuring a clear low angle of take off.  That is a near field 
effect.  However beyond the Fresnel Zone, (3 to 5 wavelengths at a band 
you are using), there can be great effects caused by land at that 
distance.  And of course, there is not much you can do to enhance the 
reflectivity there.  Things like metal ore deposits have been reported 
to affect signals at some bands.

A HF station located at the edge of a drop off often sees a signal 
advantage in the downslope direction is another observation that has 
been reported.

About all you can do for things like dense foliage near your station 
property, is to raise the antenna higher than the grove of trees; or try 
to see if a vertical antenna works better than a horizontal at your 
location.

Look up the writings on HF propagation to learn more detail.

Stuart Rohre
K5KVH