Wideband Circularly Polarized Microstrip Antenna With Wide Beamwidth

Abstract

A novel wideband circularly polarized antenna for S-band satellite communications with wide beamwidth is presented. The wide impedance bandwidth is achieved by using the modified inverted-L feeds and stacked patches. The wide beamwidth is obtained by the semi-open metal cavity. A prototype of the antenna is implemented, and the measured bandwidth is 30.1% with the reflection coefficient <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\leq \hbox{-}10~\hbox{dB}$</tex> </formula> , axial ratio <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\leq 3~\hbox{dB}$</tex></formula> , half-power beamwidth (HPBW) <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$\geq 100^\circ $</tex></formula> , and gain <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$\geq 3~\hbox{dBic}$</tex></formula> . Experimental results show that the proposed antenna has good impedance matching, circular polarization, and wide beamwidth characteristics.