Low-Profile and Broadband Dielectric Resonator Antenna Using Higher-Order Modes

The performance of a low-profile dielectric resonator (DR) antenna (DRA) is hardly maintained across a wide frequency range due to the multiple higher-order modes. In this letter, a low-profile and broadband DRA is proposed with stable broadside radiation over a wide range of frequencies. A detailed analysis of the excited modes is conducted to identify proper modes for broadband operation. Different air regions are then introduced in the top layer of the proposed DRA. This allows the excitation of the higher-order DR modes with broadside radiation while suppressing the unwanted off-boresight modes. To validate the design, the DRA is developed to cover the frequency range of 3.25–6.1 GHz for potential 5G applications. The fabricated prototype is measured showing a broad bandwidth of ∼64.2%, a peak antenna gain of ∼9 dBi, and a low profile of only ∼0.07λ0.