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spacing between the reflector and
driven element should be
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Gain
vs Spacing
The
gain of an an antenna with parasitic elements
varies with the spacing and tuning of the
elements, and thus for any given spacing
there is a tuning condition that will give
maximum gain this spacing. The maximum front
to back ratio seldom, if ever occurs at the
same condition that gives maximum forward
gain. The impedance of the driven element
also varies with the tuning and spacing, and
thus the antenna system must be tuned to its
final condition before the match between the
coax and the antenna can be completed.
However, the tuning and matching may
interlock to some extent, and it is usually
necessary to run through the adjustments
several times to insure that the best
possible tunning has been obtained. (ARRL Radio handbook)
Order
How to Build and Adjust Quads
or
The
Quad Antenna: A Comprehensive Guide to the
Construction, Design, and Performance of Quad
Antennas
For some great
construction information stop in to Scott's quad
page
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