Compact and Broadband Stacked Microstrip Patch Antenna for Target Scanning Applications

Abstract

A broadband and compact stacked microstrip patch antenna has been developed using stacked configuration. The antenna comprises two parasitic patches stacked above the driven patch fed by shifted microstrip feed and a step transformer between feed and patch to achieve broadband coupling. Cross polarization has been improved by inserting a vertical slot in the direction of feed. The antenna occupies very low volume of ${\mathbf{0}}.{\mathbf{36}}{\lambda _{{\mathbf{o}}}}\,\times\,{\mathbf{0}}.{\mathbf{39}}{\lambda _{{\mathbf{o}}}}\,\times\,{\mathbf{0}}.{\mathbf{096}}{\lambda _{\mathbf{o}}}$ (radiating elements volume), while overall dimensions with ground plane are ${\mathbf{0}}.{\mathbf{7}}{\lambda _{{\mathbf{o}}}}\,\times\,{\mathbf{0}}.{\mathbf{7}}{\lambda _{{\mathbf{o}}}}\,\times\,{\mathbf{0}}.{\mathbf{096}}{\lambda _{\mathbf{o}}}$ . The overall bandwidth achieved is 35% (4.9–7.05 GHz) and a peak gain of 8.2 dBi with average gain of 6 dBi. Antenna radiation patterns are quite unidirectional with ${\mathbf{F}}\text{/}{\mathbf{B}} > {\mathbf{21}}$ dB and significantly low cross-polarization levels, suitable for target scanning applications. In the class of printed broadband antennas with unbroken ground plane, the proposed antenna achieves minimum volume with good bandwidth and radiation properties.