Five Element Printed Modified Vivaldi Array Covering 5.3 to 20 GHz

Abstract

Isolated singular Vivaldi antennas have been in vogue for multi octave band communications and EW applications. For shared aperture EW applications phased array antennas are being used extensively. For such applications the spacing between array elements is required to be less than 0.576λ for scanning to ±45° to reduce grating and side lobes, where the wavelength (λ) at the highest frequency. Single antennas covering 6 to 18GHz when inserted in an array perform differently due to mutual coupling effects. In this paper, the single isolated antenna is taken as a reference antenna and inserted in the array and parametric studies have been carried out to arrive at an optimum solution for maximizing VSWR and pattern bandwidth in a five element array environment. A S11 of less than -7.5 dB over 5.3-18 GHz has been obtained in array environment. Satisfactory scanning of ±40°over 5.3 to 17.5 GHz is obtained for an 8 element linear array and results are presented.