Tuning stubs for microstrip-patch antennas

A practical method for the simultaneous tuning, of both the resonant frequency and reflection coefficient, of a coaxially fed rectangular-microstrip patch is described. The use of two tuning stubs allows independent adjustment of the effective patch length and the effective position of the feed point. The effective length determines the resonant frequency of the patch, while the effective position of the feed point determines the input impedance. It is demonstrated that the method allows the adjustment of the feedpoint reflection coefficient of a patch to less than -60 dB, at a frequency which is within 0.005% of specification.<
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