Topband: Noise and reception

[Tom Rauch]

> I believe the K6STI loop and even
> the Flag/Pennant family are getting unfairly slammed in the
> informal ham 'press' such as the Topband group. 

I don't think so Dave. 

I think it reasonable to point out as antennas are made smaller and 
smaller, they generally become more and more critical to build.

It is also reasonable to point out that the K6STI loop is very critical 
to construct, because the nature of the antenna makes it very 
sensitive to balance. It is so insensitive, it might not be possible to 
balance it without special "tricks" or effort.

As a matter of fact, the very thing that makes the K6STI antenna 
NOT want to work is part of what makes Beverage, EWE, Flag, 
and Pennant antennas "want to work"!!! 

For those of us with small well-balanced loop antennas, I'd like to 
suggest a little experiment. 

Take the small loop antenna and lay it over flat near the earth's 
surface, and watch the general levels of all signals. What you will 
see is a properly balanced loop just about goes dead, or at least 
has a very major reduction in sensitivity, when laid flat a few feet 
above earth.

The reason for this is simple. The earth effectively "short  circuits" 
the horizontally polarized electric field. The loop, Beverage, 
Pennant,  Flag, and even the K6STI antenna don't like to respond 
to horizontally polarized signals because of the earth. There just 
isn't much horizontally polarized signal there, if the earth has any 
reasonable conductivity. What horizontal component there is 
mainly comes from very high wave angles!

On the other hand, vertically polarized signals are re-enforced by 
the earth. Antennas near earth "want" to hear vertical signals, 
because the earth tends to re-enforce vertically polarized signals 
and cancel horizontally polarized signals.

Actually, this is also the very reason ground wave propagation 
must be vertically polarized, and why the noise that propagates 
along the earth for a distance is all vertically polarized.

We might wish otherwise, but we can't have mother earth treat one 
antenna in some special way! 

We aren't being unfair or pessimistic in telling the truth.
73, Tom W8JI
W8JI@contesting.com