A Novel Circularly Polarized Microstrip Antenna With Two Connected Quasi Monopoles for Wideband Applications

A novel microstrip antenna with an interesting radiation structure and L-shaped ground plane is presented to generate a wideband circular polarization (CP) characteristic. For this purpose, the radiation structure comprises of two truncated monopole resonators, connected to each other by a microstrip link. By adjusting the position of the link between the resonators, CP quality and bandwidth can be controlled. A single microstrip line is employed to feed one of the monopoles, and the other monopole is only matched by a proper chip resistor. Two triangle sections are also sliced from the other radiation edges to improve the impedance and CP characteristics. Moreover, because of the symmetric design of the antenna, a high purity between the right- and left-handed CP patterns and wide CP beamwidth are achieved. The antenna is fully studied and manufactured that its results are 53% (1.69~2.92 GHz) for 3-dB axial-ratio bandwidth, 62% (1.68~3.2 GHz) for 10-dB return-loss bandwidth, and gain range between 2 and 4.2 dBi across the CP band.