Wideband stripline fed tapered slot antenna with integral coupler for wide scan angle active phased array

Abstract

A stripline fed tapered slot antenna (STSA) with integral coupler operating as an active array element over 1.5 octave bandwidth is presented. The proposed STSA with integral coupler features wideband transition which allows a direct 50 Ω stripline feed and enables the coupler to be integrated along with the feed. The coupler helps in taking a sample of signal for online performance monitoring and active phased array calibration. The measured results of antenna element have exhibited good radiation pattern performance with low cross-polarisation in principal plane and low beam squint. Using this, a 16-element H -plane linear phased array antenna designed for the frequency range of 6-18 GHz and azimuth scan coverage of 60° is also presented. The active reflection coefficient of the array is calculated from measured mutual coupling coefficients and the array pattern over different scan angles is demonstrated. The grating lobe free scan coverage of 60° is obtained. The antenna array finds application in airborne systems.