[TowerTalk] antennas and buildings

[Jim Lux]

At 03:14 PM 9/29/2003 -0400, Stephen Reichlyn wrote:
>I've done a quick search of the Internet and can find almost no information
>about the effect of mounting an antenna (vertical) in near proximity to a 
>two or three
>story house (wood). What degree of signal blocking takes place in the 
>direction of the house

I don't know that any blocking, per se, would occur for an HF antenna.  The 
house is of dimensions comparable to a wavelength and in the near field.  I 
can say that from a theoretical and a practical experience standpoint that 
the pattern WILL change, but whether for the better or worse, it's hard to 
say.  (well... almost certainly for the worse, given that the house is a 
lossy structure, so some RF power will be dissipated.)

COnsider also that the house might be wood, but it probably has:
1) foil insulation
2) pipes
3) electrical wiring
all of which have some effect on the antenna.

One way to do a rough and ready evaluation would be to build a simple NEC 
model of the antenna, then add a rough box the size of the house made of 
lossy wires (just make the resistance fairly high) or even with 
not-so-lossy wires, and see how much current is induced.  I've done this to 
evaluate, for instance, whether the rain gutter is going to be a 
problem.  Good for a qualitative check (no current induced= no rf effect) 
but I wouldn't bet on the quantitative results.

You might find that the house acts as a parasitic director and the gain is 
actually increased in the direction of the house.


>(if any?). Any info, real or anecdotal, would be appreciated.
>
>73,
>Steve AA4V
>
>Stephen Reichlyn
>Ryan Scientific, Inc.
>843-884-4911 ext 302
>843-884-5568 (fax)
>www.ryansci.com

Jim W6RMK