ABSTRACT
Low profile microstrip patch arrays are preferred in stealth technologies due to their conformal property, ease of fabrication and low weight. One of the disadvantages of patch arrays with microstrip feed is the narrow bandwidth. Thicker substrates with lower dielectric constant can be used to improve the bandwidth. However, larger thickness cause increase in the surface waves and unwanted radiation from the feed network. Further, a corporate feed network in patch arrays consumes comparatively larger area when compared to a series feed network. Aperture coupled feeding technique can be introduced to overcome the bandwidth limitation, but has the disadvantage of backward radiation due to the feed network at the lower side of the patch array. Since the additional layer further complicates the total array structure, a proximity coupled feeding technique having maximum impedance bandwidth and minimum spurious radiation can be a choice. In this chapter, the RCS reduction feature of HIS and proximity coupled feed network is combined to design a patch array. The EM design and analysis of proximity coupled patch array with conventional ground plane, slotted ground plane and hybrid HIS-based slotted ground plane have been presented. The radiation and scattering characteristics (structural/radiation mode RCS) of the patch array are discussed.
