Topband
[Top] [All Lists]

Re: Topband: Flags and loops in restricted space

To: 'Björn Mohr' <bm@broadcast.se>,<topband@contesting.com>
Subject: Re: Topband: Flags and loops in restricted space
From: "n4is" <n4is@bellsouth.net>
Date: Sat, 29 Dec 2007 15:19:55 -0500
List-post: <mailto:topband@contesting.com>
Hi Bjorn

It depends, the loop is resonant, and any resonant antenna will reradiate
signals and noise. You can have any non resonant antenna close to each
other, like several EWE's or Flags, they are the same class no resonant
antenna.

Remember how a Yagi antenna works with Reflectors and Directors close to 1/2
wave length, the elements are close to resonance and couple with each other.

The TX antenna is also resonant and you need to detune it during RX, in my
case my RX antenna is only 50 ft from my TX antenna, and when I detuned the
TX antenna, I can see 2 S units drop in noise on my RX antenna.

Common mode noise is very important to keep it very low, RF chokes and good
ground is very important to receive only the signal from your RX antenna,
Beverage, EWE or flag and not from the feed line, the external cable coax
shield can pick up a lot of signals too. 

Any cable that?s run in parallel induce common mode noise, so you need to
care rotor cables, AC cables any thing that can become part of you RX
antenna system, Including TX isolation signals that can leak from the TX
cable into the RX port. 


Regards
Carlos
N4IS

_______________________________________________
Topband mailing list
Topband@contesting.com
http://lists.contesting.com/mailman/listinfo/topband

<Prev in Thread] Current Thread [Next in Thread>