Parallelogram Arrays

Author: Edmund A. Laport

Four identical vertical radiators arranged in the form of two crossed pairs with identical centers constitute a parallelogram array. Such arrays provide a very large variety of useful radiation patterns both symmetric and asymmetric. The resultant pattern from two crossed, cocentered pairs is the sum of the two pair patterns, provided that the phase reference for the currents in both pairs is taken to be zero at the center of the array. The relative size of each pair pattern can be changed by altering the power distribution between pairs. The individual patterns are in terms of field strengths, with the polarity of the electric field in each lobe indicated.

Given two overlapping patterns, one can be rotated with respect to the other by changing the angle between the axes of the two pairs.

The independent variables in a paralellogram array are the following:

1. Spacing between radiators in each pair, S₁ and S₂

2. Phase differences between the currents in each pair, ±φ1/2 and ±φ2/2

3. Relative current amplitude differences between pairs, I₁/I₃

4. Angle between the axes of the two pairs, βx (this angle can lie anywhere in four quadrants)

5. Orientation of the entire array, β0