Single-Fed Circularly Polarized Dielectric Resonator Antenna with an Enhanced Axial Ratio Bandwidth and Enhanced Gain

A compact single-fed circularly polarized dielectric resonator antenna (DRA) with an enhanced 3-dB axial ratio bandwidth (ARBW) and gain is proposed. The DRA is implemented by joining a smaller dielectric resonator (DR) to one side wall of a main rectangular DR and is excited by an offset vertical metallic strip. With this configuration, two sets of degenerate orthogonal modes, the $TE_{111}$ mode and $TE_{113}$ mode, are simultaneously excited to realize wideband circular polarization operation. Furthermore, by removing a small DR portion from the lower corner of the main DR, the boresight gains at higher frequencies are significantly enhanced. An antenna prototype is fabricated and measured to verify the performance of the proposed design. The experimental results illustrate that the proposed antenna achieves a measured 3-dB ARBW of approximately 44.73% (3.68-5.80 GHz) in conjunction with a broad-10 dB impedance bandwidth of 69.66% (2.9-6.0 GHz). The measured boresight gain is found to be 5.49± 0.85 dBic within the passband with a maximum value of 6.34 dBic at 4.7 GHz. Moreover, reasonable agreement between the simulated and measured results is achieved.