TopBand: Re: Topband: jps ANC-4

[Mike.Tope@Sciatl.COM]

          Rolf,
          
          The likelihood of this happening depends on the width of the 
          null, which is a function of the spacing between the two 
          antennas (main antenna and noise antenna). If I remember my 
          antenna theory correctly, wider spacings will generally  
          produce sharper nulls. The wider the null, the larger the 
          blind spot that you will have. For a given angular 
          separation between  between the offending noise source and a 
          desired signal, the degree of Signal to Noise (SNR) 
          improvement will depend on the amplitude taper of the null. 
          For example if the taper of the null is 5db/degree and the 
          two sources are 3 degrees apart in azimuth, you should be 
          able to improve the SNR by about 15dB. In some cases you 
          will actually be putting the desired signal into the null, 
          but not as far as the interfering signal. Its kinda like 
          tuning for maximum amplitude slope. This might expain why I 
          sometimes get the best SNR on a signal if I don't null the 
          noise completely. This is all theory and conjecture of 
          course. Good luck with your ANC-4. I would be dead in the 
          water on topband without mine.
          
          73 de Mike, W4EF

--
FAQ on WWW:               http://www.contesting.com/topband.html
Submissions:              topband@contesting.com
Administrative requests:  topband-REQUEST@contesting.com
Sponsored by Akorn Access, Inc & N4VJ / K4AAA