IMPROVING THE SCAN PERFORMANCE OF PROBE-FED MICROSTRIP PATCH ARRAYS ON HIGH DIELECTRIC-CONSTANT SUBSTRATES

This paper presents a thorough investigation into the use of E-plane p arasitic elements to remove scan blindnesses in probe-fed microstrip p atch phased arrays using a rigorous full-wave analysis. It is shown th at the addition of an E-plane parasitic element in the unit cell of th e array can enhance the impedance scanning range; however, the parasit ic element must be resonating, As a consequence of this, the method of scan blindness removal is only suited to microstrip patch arrays moun ted on high dielectric constant material. A novel configuration incorp orating a varactor diode to reduce the significant reactive nature of the input impedance at large scan angles is introduced which further i mproves the scanning potential of the parasitic element array. A furth er modification to the unit cell is proposed which allows the array to operate over a broad frequency range. For all the configurations cons idered, comparisons of active reflection coefficient, scan impedance b ehavior, efficiency, and cross-polarization levels are presented.