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Cubical Quad Antenna Calculator

Enter center frequency: MHz

Element: Total Length One side Spreader "C"
Driven Element
Director 1 (optional)
Director 2 (optional)
Director 3 (optional)
Director 4 (optional)
Director 5 (optional)
Lengths: Inches / cmts Inches / cmts Inches / cmts
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C=Spreader arm Length
Reflector tuning stub

Spacing between the reflector and driven element should be 


Spacing between the driven element and the first director and between the directors should be


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 tuning has been obtained.

(ARRL Radio handbook)

Created by: Ron A Van Varden - N6ACH (ex. KD6DKS)

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