Compact and Broadband Stacked Microstrip Patch Antenna for Target Scanning Applications

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 0.36λ
_o
× 0.39λ
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× 0.096λ
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(radiating elements volume), while overall dimensions with ground plane are 0.7λ
_o
× 0.7λ
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× 0.096λ
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. 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 F/B > 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.