Cubical Quad Antenna Calculator.

The spacing between the reflector and driven element should be inches or centimeters.

The spacing between the driven element and the first director and between the directors should be inches or centimeters.

The gain of an an antenna with parasitic elements varies with the spacing and tuning of the elements, and for any given spacing there is a tuning condition that will give maximum gain to 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 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.

The antenna can be fed directly with 50 ohm coax, however, in some cases a 1/4 wave 75 ohm transformer may need to be used to aid matching. Remember also that for vertical polarization feed the driven element from the side of the diamond or square, and for horizontal polarization feed the driven element at the bottom of the diamond or sqaure.