View Single Post
  #10   Report Post  
Old December 9th 04, 02:40 AM
John Doty
 
Posts: n/a
Default

Mark Keith wrote:

I guess I have one issue though, and yes, I am anal retentive...I object
to *any* antenna being called a "low noise" antenna. Why? Cuz they don't
exist. These is no such thing. They should describe all of these types
of decoupled antenna schemes as "examples of better decoupled antenna
*systems*.


One trouble is that many potential readers wouldn't understand such a
pedantic article title.

The lower noise has nothing to do with the antenna itself.
Only the decoupling of the line, coax or ladder line.


You can't decouple the line from an unbalanced antenna that lacks a
counterpoise. You can argue that really isn't an antenna (and I would
agree!), but such things are sold as "antennas". The most commonly
recommended "antenna" for the newbie is a "random wire", technically
only half of an unbalanced dipole. Even professionals aren't immune from
this technical error: unbalanced dipoles are often called "monopoles"
even though Maxwell's equations forbid a true monopole antenna.

Even if a counterpoise is present, the design of the antenna influences
your ability to effectively decouple it from the line. Ungrounded but
unsymmetrical antennas (like "slopers") are particularly troublesome.

And to top this
off, if you are in a quiet area with no noise to pickup, using the
decoupling schemes will not do *anything* at all to reduce noise. The
performance will be exactly the same. IE: out in the woods, running
battery power, etc...A *true* noise reducing *antenna* would work
anywhere, but again, as far as I'm concerned, they don't exist.


In the article in question, I wrote, "The real trick with a shortwave
receiving antenna system is to keep your receiver from picking up noise
from all the electrical and electronic gadgets you and your neighbors
have". Plainly, I was not talking about receiving systems out in the woods.

I'm a professional physicist: I can be as fussy and pedantic as you'd
like. Unfortunately, that rarely leads to effective communication. SWL's
write to me to tell me that following my advice has improved their
reception, and several DX websites host copies of my article. I like to
think that shows I've communicated something that matters to people. You
seem to know quite a bit about this stuff: why not write up *your*
approach to these issues?

-jpd