Good Evening Len and all.
I recognize the statements you refer to as being from my recent 8 element
antenna article posted to my website. First let me say that I cannot speak to
the Dx Engineering RX 4 square at all as I have no experience there. I have
built a few of my own 4 squares with great results however. The comments about
voltage gain and phase shift apply only to my system as described in the 8
element article. The Hi-Z amplifier along with the antenna element mounting
arrangement apply a load capacitance to the antenna element itself. This load
capacitance is right at 30pf. The antenna element itself in the form of a thin
10 foot element has a source series capacitance of right around 30 pf. This
forms a voltage divider of about .5 to 1. A 6 Db loss. If you increase the
length and diameter of the element to 20 feet and about 3/4 inch dia. The
series capacitance increases to about 60 pf. This reduces the voltage loss to
about 3.5 Db. You also get the extra voltage gain as a result of th
e longer element. In addition I have modeled this system and found a change in
the amplifiers output phase of about 2 degrees going between the two element
sizes. These numbers were important to me in the 8 element design however it is
my opinion that you would likely see no discernable changes in a simpler 4
square antenna as long as all your elements were reasonably identical.
73
Lee K7TJR www.k7tjr.com
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