Circularly Polarized Spherical-conformal Dielectric Resonator Antenna with Wideband and Wide Beamwidth

In the paper, a circularly polarized (CP) spherical-conformal dielectric resonator antenna (DRA) with the features of wideband and wide beamwidth is proposed. It consists of a bent DR with a conical cavity, a bent slotted ground, a spherical shell substrate and a bent L-shaped microstrip feeding line. By exciting the bent DR with a bent L-shaped feeding line through a bent Z-shaped slot ground, wide impedance and CP bandwidths are obtained. While wide HPBW is achieved by changing the bending degree of the DR. To keep symmetrical radiation patterns within different cut planes, the DR is slightly rotated along the x- and y-axis. Moreover, to reduce the deterioration degree of 3-dB ARBW induced by the conformal, a conical cavity is dug out in the DRA and the size of the ground plane is cut. Design evolutions of the proposed antenna are given to exhibit the mechanisms of each development. Parameter analyzes are also provided to show the effects of main parameters. Results show that from 1.08 GHz to 1.86 GHz (53.1%), the return loss of the DRA is larger than 10 dB. While within the fractional bandwidth of 20.6% (1.09 GHz to 1.34 GHz), the axial ratio is smaller than 3 dB and the gain is larger than 2.98 dBic. According to the radiation patterns, the patterns are symmetrical and consistent among the different cut planes. And the HPBWs are larger than 135° at the four cut planes (φ = 0°, 45°, 90°, and 135°) which contribute to the bending of the DRA. In addition, the 3-dB ARBWs at these cut planes are in the range of 105°–183°, which is match with the HPBW. In summary, the paper proposed a novel technique to broaden the HPBWs of a wideband CP antenna, which simultaneously has less affects to the 3-dB ARBWs.