A Wideband Single-fed circularly polarized dielectric resonator antenna with bandpass filtering response

For integrated design of a filter and an antenna, a wideband circularly polarized (CP) dielectric resonator antenna (DRA) with filtering characteristics is proposed. A rectangular slot structure is etched on the ground to optimize the axial ratio (AR) bandwidth of the antenna singly fed by one port. Capacitive filtering branches are combined into the microstrip feeding line to effectively generate two radiation nulls outside the passband. To further enhance the suppression level in the high-frequency stopband, the stair-shaped DR is chamfered into a fish-shaped structure. A suppression level larger than 15 dB is found within the stopband. A prototype of the antenna is fabricated, and both of the simulated and measured results show a wide bandpass filtering performance over the operating frequency band. The antenna has an impedance bandwidth of 37.8%, an AR bandwidth of 25.1%, and a low profile of 0.078 lambda(0) (lambda(0) is the free-space wavelength at 5.47 GHz), which can be a good candidate for 5 G and WLAN communication systems.