[Antennas] Matching using coax

Thu Mar 15 21:34:27 EST 2007

There are probably 100 ways to match your array, and using coax matching 
sections is certainly one of those ways. It is also not easy, but then none 
of the ways are easy. Impedance matching is not a simple topic. For this 
type of application, the best place to get up to speed quickly is the Smith 
Chart. One evening of study ought to at least give you an idea of what you 
can do with series transmission line segments.
73 de W9DMK, Bob in Dahlgren, VA
http://www.zaffora.com/W9DMK/W9dmk.html
----- Original Message ----- 
From: "Jim Miller" <JimMiller at STL-OnLine.Net>
To: <antennas at mailman.qth.net>
Sent: Monday, March 12, 2007 11:35 PM
Subject: [Antennas] Matching using coax
I want to build a moxon rectangle array of 2 over 2 for 2 meters. All 4 
would be fed and all in phase. The overall dimensions of the array are 19 
inches x 85 inches giving a turning circle of about 22 inches. This is 
supposed to fit in the attic and be rotatable showing a gain of over 9 dBd 
with a radiation angle of 5 degrees and a 3dB azimuth of almost 90 degrees.
#1 - Here is the question. I read "somewhere" about using 50 and 75 ohm 
coax to transform impedances. I think the article was for 4 verticals (in a 
row?) and they used only coax to MATCH (to get the 12 ohms to 50 ohms). I 
didn't completely understand, have no idea where I saw it, but would like 
to do this.
#2 - Is there a better (easy) way to match this?
Thanks es 73, de Jim KG0KP
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