Gain-Bandwidth Trade-off Reduction in an H-Shaped Dielectric Resonator Antenna Using Coplanar Substrate Integrated Waveguide Feeding for 5G Application

Abstract

Due to the simplicity of the geometry, Rectangular Dielectric Resonator Antennas (RDRAs) are widely used, and they provide more flexibility in controlling the resonant frequency by varying the length, width, and height of the antenna. The traditional RDRAs, however, usually have a trade-off between gain and impedance bandwidth, and it is difficult to enhance both parameters simultaneously. Such a gain–bandwidth trade-off is a key issue in antenna design, particularly for new 5G wireless communication systems that require high gain and wide bandwidth with a compact antenna profile. To solve this problem, this paper introduces an improved design method for reducing the gain-bandwidth trade-off based on the combination of the CP-SIW feeding mechanism and an optimized H-shaped dielectric resonator structure. In this study, the antenna was excited using a Coplanar Substrate-Integrated Waveguide (CP-SIW) feeding mechanism with a modified resonator geometry. The CP-SIW feed contributed to the improvement in antenna gain, while the impedance bandwidth was enhanced through the transformation of the conventional RDRAs into an H-shaped resonator configuration. The antenna was fabricated on a Rogers RT/Duroid 5880 substrate (εr = 2.2) with a thickness of 1.57 mm. The dielectric resonator was made of ceramic material with a relative permittivity of 15, while the modified H-shaped structure was studied using an effective permittivity model, considering the dielectric, substrate, and air regions. The simulated results showed a clear improvement in performance, where the impedance bandwidth increased from 10.3% for the conventional RDRA to 13.9% for the proposed H-shaped Dielectric Resonator Antenna (H-DRA). In addition, the antenna gain significantly improved from 3.92 dBi (without SIW integration) to 9.3 dBi with the CP-SIW feed, and slightly decreased to 9.14 dBi after implementing the optimized H-DRA configuration. The radiation efficiency did not fall below 98%, which is considered excellent energy efficiency. The measured results are also presented to further validate the simulation results, in which the fabricated prototype was found to have a measured bandwidth of 27.7% and a peak gain of 8.29 dBi. The simulated results suggest good agreement with the measured results, which confirms the validity of the proposed design. Overall, the proposed CP-SIW-fed H-shaped DRA offers a promising solution for reducing the gain–bandwidth trade-off in high-performance 5G wireless communication applications.