[Lowfer] Noise Canceler Effectiveness... How it REALLY works ??

[jrusgrove at comcast.net]

Some info on terminated receive loops is available at http://www.w3eee.com/ ... scroll down to receive antennas.

I use a large K9AY for 137 and 500 kHz. A drawing of the antenna is available at http://www.w1vd.com/k9ay11.pdf. The Vactrol terminating resistor is adjustable from the shack. I find that the resistance required for optimum front to back is the same regardless of the direction selected. The antenna maintains excellent directivity as one goes lower in frequency  -  at 60 kHz the F/B is 20+ dB - same as it is at 137 and 500 kHz. Directivity falls off at frequencies greater than 1 MHz.    

Jay W1VD  WD2XNS  WE2XGR/2
  ----- Original Message ----- 
  From: Bill Ashlock 
  To: lowfer at mailman.qth.net 
  Sent: Wednesday, January 14, 2009 5:06 PM
  Subject: Re: [Lowfer] Noise Canceler Effectiveness... How it REALLY works ??


  Hi Alan,
   
  I think this antenna is far too small (WL wise) to have the properties you describe. The basic antenna looks like a small loop and a E-field sensing antenna to me and I believe the resistor is introducing what is sometimes referred to as an "Antenna Effect" or an undesired susceptibility of a loop to the E field, which tends to modify the figure "8" pattern - but in this case it is adjustable and becomes a desired effect. Any comments from others?
   
  Bill 

  > From: alan.melia at btinternet.com
  > To: lowfer at mailman.qth.net
  > Date: Wed, 14 Jan 2009 14:39:24 +0000
  > Subject: Re: [Lowfer] Noise Canceler Effectiveness... How it REALLY works ??
  > 
  > Hi Ok on the loops but this form of noise canceller works with two end fed
  > wire antennas too...... which dont have "fig of 8" patterns !!
  > 
  > On the K9AY I have reservations about that explanation too because the K9AY
  > is not a loop....it is more like a travelling wave antenna. It may be the
  > model works, but I prefer to compare it with a coupled line. Think of a
  > directional coupler only here the coax/waveguide is the earth ionosphere.
  > Then the coupled line is a line terminated in a resistor where a signal
  > from one direction is absorbed in the matching resistor. The matching
  > resistor need changing depending on the direction in the K9AY ....varying
  > the orientation of a pick-up loop in coax changes it impedance, and so
  > requires a different termination. Any comment ?? There are elements of this
  > in a Beverage too.
  > 
  > Alan G3NYK
  > 
  > 
  > 
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