This paper presents a novel method to suppress the higher order harmonics in the microstrip patch antennas. A practical 0.75 GHz microstrip patch antenna is fed with a quarter-wave feedline designed by exploiting the dispersion properties of shunt-capacitor-loaded transmission-line metamaterials. It is shown that two higher order harmonic modes at 1.25 and 1.5 GHz are completely eliminated. In addition, there is about a one-fourth reduction in the length of the impedance matching quarter-wave feedline.
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