A low-profile wideband dielectric resonator antenna suitable for beam-steering applications

Recently, to solve the huge volume of conventional dielectric resonator antenna (DRA), the innovative low-profile DRAs, such as dense dielectric patch antenna (DDPA) and planar DRA, have been developed, and quickly become the hot spots. However, the existing low-profile DRA designs have disadvantages such as large planar sizes (>0.5λ₀×0.5λ₀) or narrow bandwidths (<10%), which limit their applications. In this paper, a low-profile wideband DRA with a miniaturized planar size is studied. This antenna adopts a dense dielectric patch resonator (DDPR) design, which has a high permittivity dielectric sheet on the top, a low permittivity substrate in the middle, and a slot feeding structure on the bottom. The slot feeding structure can excite two working modes of the DDPR, which are TE₁₁₁ and TE₁₃₁, respectively. The two modes have very different field distributions at the edge area of the DDPR, that is the E-field distribution of TE₁₁₁ is very weak while the E-field of TE₁₃₁ is quite strong. Based on the observation, we propose a technique of slightly increasing the height of the edge area of the DDPR, which can significantly affect the TE₁₃₁ resonant frequency while slightly affect the TE₁₁₁ resonant frequency. With this technique, the resonant frequency of TE₁₃₁ mode can be quickly pulled down and merged with that of TE₁₁₁ mode. The operating bandwidth, therefore, can be greatly enhanced without increasing the planar size of the DDPR. The size of the antenna is kept as 0.35λ₀×0.35λ₀×0.08λ₀. Measured results show that the linearly polarized antenna prototype has a −10 dB impedance bandwidth of 18.5% and a maximum gain of 7.3 dBi. Simulated results of the 1×5 array show that the antenna is suitable for beam-steering applications. Further, the design concept is extended to a design of circularly polarized antenna, which also has a compact size and an enhanced bandwidth.