[Lowfer] Best Phase Shift article I know of...

[wa3tts at verizon.net]

Hi All:  The best article on phase shifting networks I know of in terms of clarity and conciseness is:

"Matcing Networks and Phasing,"  W. C. Alexander, Crawford Brodcasting Company, Denver, Colorado.

https://crawfordbroadcasting.com/Eng_Files/Matching%20Networks%20and%20Phasing.pdf 


I suggest starting with Part 8.0 of this article, Phase Shift Design, as it describes what you need to do.   Then go back to the beginning of the article and 
read Parts 1.0 Matching Networks, 1.01 L Networks, 1.02 T Networks, and 3.0 Phase Shift Networks.  Everything you 
need to know about building simple T and L phase shift circuits for your frequency of interest is there.  The math is fairly straightforward
for determining inductive and capacitive reactance values for the phase shift newtork component values.

You can use online L and C reactance calculators of your choice to confirm the needed L and C values in microhenries and microfarads once the L and C reactance values are determined.
My receiving antenna feedline lengths for LF/MF antennas are 40 to 50 meters long, which is less than 3 percent of a wavelength at 1750 meters.
My antenna ground impedance for my receive antennas at LF and MF  likely varies more than 3 percent with changing ground moisture levels.  If you follow the 20 percent
tolerance suggestion in Part 8, I would think the resulting L and C reactance  values would cover the small  phase shift of the receiver feedline at 137 or 185 kHz.

One goal of using such  passive T and L phase shift circuits would be having less RF throughput loss versus the 8dB loss that is typical of the Phase-X or ANC-4 active phasing units.  
I think understanding the component values you need to achieve 180 phase shift for "noise" cancellation at a frequency of interest is essential for having an efficient receiving system.

Of course, the antenna feedline phase shift would be significant for 40 or 50 meters of feedline at 160 meters, but at LF the feedline phase shift contribution is relatively small.
73, Mike wa3tts


-----Original Message-----
From: John Bruce McCreath <weazle at hurontel.on.ca>
To: Discussion of the Lowfer (US, European, & UK) and MedFer bands <lowfer at mailman.qth.net>
Sent: Wed, Dec 28, 2022 7:34 pm
Subject: Re: [Lowfer] RF Noise Canceller


Hi Tom…..thanks for the link to the noise canceller site.  I took a quick look at it,
and was disappointed that none of the pictures came thru, just the text.  I’ll give
it a couple of tries later, as it may have been a temporary glitch.

Your comments on the toroid vs binocular core back up what I’ve discovered
myself while toying with antenna matching, etc.  Huge improvement in all the
cases I tried.

Tnx & 73, J.B., VE3EAR


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