[BC] RF absorption by foliage

[DHultsman5@aol.com]

In a message dated 10/30/2005 5:37:16 PM Central Standard Time,  
paul at amtower.com writes:

Also  around Flat Rock we have another strange anomaly.  I have seen
>  locations in the middle of a clear square mile, can't blame it on  wires,
> where the FIM read some number, say 1mV and a second later its  5 mV a
> second later its back to 1 mV.  The meter will bounce  fast, not slow, but
> fast between two numbers on one second intervals  and do it for hours.  On
> some radial heading it will do this for  miles along the radial.  There is
> no click or snap in the  audio.  It has something to do with the ground
>  conductivities.  Sometimes when near a power line the effect goes
>  away.  Its the strangest darn thing.  I figure that up in  Detroit



This problem usually occurrs when the null is very deep.  As  modulation 
occurrs the power in the sidebands is not nulled as is the carrier  power.  This 
will cause the FIM readings to appear to jump.  My  experience was that this 
would happen on our deepedst null and only on the  deepest null.  My boss 
claimed something was loose in the system.  I  checked every connection electrically 
and mechanically in the system at least  twice.
 
Theoadore Giles with Ralph Bitzer came an looked at the readings and  
explained that the phasor was nulling perfectly at carrier but with high  modulation 
the FIM would jump due to the ratios of the power in the  sidebands vs. power 
in the carrier.  
 
Dave Hultsman
 
>From Scranton, PA