A scheme to lower the resonant frequency of the microstrip patch antenna

Simple schemes are presented for lowering the resonant frequency of the rectangular patch antenna without changing its size. In particular, by placing a perturbance below the patch it is shown that as much as a 30% decrease from the resonant frequency of the unperturbed patch can be achieved. The specific configurations considered include a cavity-backed and an aperture-backed patch, and for each case design curves are presented.<
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