High-Efficiency Circularly Polarized Dielectric Resonator Antenna Array Fed by the Cavity-Backed SIW

A novel circularly polarized (CP) dielectric resonator antenna (DRA) array is introduced. The DRA element operating at the desired frequency is determined by the dielectric waveguide model (DWM), and two orthogonal modes are generated to excite CP waves. A 4 x 4-element DRA array is then developed. The array is fed by the cavity-backed slotted substrate integrated waveguide, without using extra feeding network. Experimental results show that the array obtains a bandwidth of 240 MHz (9.88-10.12 GHz) for reflection coefficients and axial ratios (ARs) less than -10 dB and 1 dB, respectively. Moreover, the array obtains a 16 dBic peak gain, a -33.6 dB cross-polarization level at the boresight, namely 0.5 dB AR at the center frequency, which demonstrate the desirable array performance. In addition, above 62.5% aperture efficiency and above 90% radiation efficiency are realized over the operating bands, with about 76% peak aperture efficiency and about 94% peak radiation efficiency. The proposed array can be regarded as an element to form large planar arrays, which will be useful in beamforming systems. Our design idea may open a new way for developing high-efficiency large millimeter-wave arrays.