http://www.n6mrx.com/Antenna/Cubical-Quad1.htm

Enter center frequency to be calculated for a quad : If you want to use it between 144 mHz and 146 mHz enter 145 in the mHz box.

Frequency		mHz
.		.	.	.

	Total Length	ONE SIDE	Spreader Arm Length ONE SIDE "C"
Reflector	inches centimeters	inches centimeters	inches centimeters
Driven Element	inches centimeters	inches centimeters	inches centimeters
Director 1 optional	inches centimeters	inches centimeters	inches centimeters
Director 2 optional	inches centimeters	inches centimeters	inches centimeters
Director 3 optional	inches centimeters	inches centimeters	inches centimeters
Director 4 optional	inches centimeters	inches centimeters	inches centimeters
Director 5 optional	inches centimeters	inches centimeters	inches centimeters

C= Spreader arm Length

Reflector tuning stub

spacing between the reflector and driven element should be

	inches
	centimeters

.
spacing between the driven element and the first director and between the directors should be

	inches
	centimeters

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)

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