A compact wideband filtering rectangular dielectric resonator antenna with U-shaped metal strips

In this paper, a compact wideband filtering rectangular dielectric resonator antenna (RDRA) loaded with a pair of U-shaped metal strips is proposed. By using a slot-coupled feeding structure, a rectangular DR with a length-width ratio of 3:1 is selected to combine the resonant frequencies of the TE111 and TE121 modes to achieve the passband. Two pairs of transverse branches with different lengths are added to the longitudinal microstrip feeding line, and the TE111, TE11+delta 1, and TE121 modes are successfully excited to enhance the bandwidth. The short pair of transverse branches can generate a null high-frequency radiation. A pair of U-shaped metal strips is loaded at both ends of the top of rectangular DR, introducing a low-frequency radiation null. Both radiation nulls can be independently adjusted. A pair of rectangular grooves is etched inside rectangular DR to boost the impedance matching level. The proposed filtering RDRA has been fabricated and measured for verification. The measured relative impedance bandwidth is 22.67% (4.34-5.45 GHz). The measured average gain and peak gain are 7.19 dBi and 8.06 dBi, respectively. RDRA filtering has broad application potential in modern communications, such as the N79 band.