Asymmetric CPW-fed Wideband Circularly Polarized Antenna for Sub-6 GHz Application

This paper describes a design of asymmetric coplanar waveguide-fed circularly polarized (CP) antenna for massive machine-type communication in Sub-6 GHz. The asymmetric CPW structure achieves a CP radiation at the upper band. The proposed antenna consists of a modified trapezoid with an extended strip and an L-shaped strip connected to the ground. By utilizing the extended strip, the axial ratio at the lower band is improved. By simulating and optimizing in the CST, the result shows that the axial ratio bandwidth (ARBW) of the antenna is 92% (2.2-6 GHz) and its impedance bandwidth is 100% (2-6 GHz). The antenna covers most of the Sub-6 GHz frequency band, with an overall size of 60 mm × 80 mm ×1 mm. The variation of the gain of the antenna is between 1.3 dBi to 3.7 dBi.