The Effect of the Mutual Impedance Due to the Neighbouring Elements on the Driving Point Impedances of a Linear Array

Abstract

In the case of a closely spaced free space linear array, the driving point impedance of every element has been shown to be a function of the angle of the oncoming wave-front, in addition to its being different from one another. The driving point impedance curves for various close spacings for the case of a 4-element array suggest that it is best to avoid spacings below 0·25 λ between the adjacent ends where the direction of the beam is required to be varied by introducing extra phase angle between elements. For spacing below 0·25 λ there is need for re-matching whenever the beam direction is required to be changed.