Triangular slotted ground plane: a key to realizing high-gain, cross-polarization-free microstrip antenna with improved bandwidth

A simple rectangular microstrip antenna with triangular slotted ground plane has been studied both theoretically and experimentally to improve shortcomings like low gain (5–6 dBi), narrow bandwidth (3%–4%), and poorcopolarization (CP) to cross-polarization (XP) isolation, i.e. polarization purity (typically 10–12 dB), of conventional rectangular microstrip patch antennas. By placing two pairs of triangular shaped slots on the ground plane just below the nonradiating edges of the patch, high gain (around 9 dBi) and more than 22 dB polarization purity over a wide elevation angle has been achieved. The proposed antenna covers almost the full X band of frequency from 9.55 GHz to 11.43 GHz while resonating at 10.35GHz (i.e. impedance bandwidth of 17%), so the proposed antenna offers improvedgain, impedance bandwidth, and polarization purity simultaneously as compared to conventional rectangular microstripantennas. Parametric studies have been documented to achieve the optimum defect dimension. The specialty of theproposed antenna is that the gain and radiation pattern is quite stable in the entire operating frequency band, alongwith its attractive gain, impedance bandwidth, and polarization performance. The simulated and measured results showclose resemblance to each other. The proposed geometry is quite simple and easy to fabricate and therefore may beideal for applications where high gain, stable radiation characteristics, and wide impedance bandwidth along with highcopolarization to cross-polarization isolation over wide elevation angles are required.

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