Abstract
In the design of circularly polarized (CP) dielectric resonator antenna (DRA) arrays, the regular-shaped DRAs with simple feeding configurations are mostly used as array elements to make the design procedure more efficient. However, such array element DRA usually achieves only about 6% axial ratio (AR) bandwidth. In this paper, a CP DRA element coupled by a fractal cross-slot which can radiate efficiently and excite the rectangular DRA simultaneously is considered. By adjusting the dimensions of the fractal cross-slot properly, the resonances of the fractal cross-slot and the dielectric resonator can be merged to obtain a wider AR bandwidth. Based on the proposed fractal cross-slot-coupled CP DRA element, two different CP DRA arrays are designed: a wideband CP DRA array and a low-sidelobe-level (SLL) CP DRA array. The designed DRA arrays are fabricated and measured, and structures and performances of the arrays are presented and discussed.
Highlights
Over the last decades, dielectric resonator antenna (DRA) have become more and more popular because of their high radiation efficiency due to the absence of conductor as well as surface wave loss
Most designs of circularly polarized (CP) DRA arrays are based on the sequential feeding technique which was proposed by Huang to generate the CP array with linearly polarized (LP) elements [2]
The parameters of the array element are optimized by the FEM-based commercial software HFSS, and the final parameters of the array element are as follows: wf = 1.52 mm, lf1 = 25 mm, lf2 = 4 mm, ls1 = 9.7 mm, ws = 0.4 mm, ks = 0.57, and φ = 50°
Summary
DRAs have become more and more popular because of their high radiation efficiency due to the absence of conductor as well as surface wave loss. DRAs can be fed by various feeding techniques, such as the microstrip line feed, the coaxial probe feed, the coplanar waveguide feed, and the aperture coupling feed. Initial studies of DRAs were concentrated on linearly polarized (LP) designs. Most designs of CP DRA arrays are based on the sequential feeding technique which was proposed by Huang to generate the CP array with LP elements [2]. Three different kinds of microstrip feeding network for sequential feeding technique are studied in [3], and the hybrid ring feeding network shows a better performance than the parallel feeding network and the series one
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