A conformal quasi-isotropic dielectric resonator antenna for wireless capsule endoscope application

—A conformal quasi-isotropic dielectric resonator antenna (DRA) is first investigated for wireless capsule endoscope (WCE) application under the 5.8-GHz industrial, scientific, and medical (ISM) standard. The probe-fed hemispherical DRA (HDRA) is studied to match the shape of the spherical dome end, and the characteristic mode analysis (CMA) tool is applied to analyze the resonant modes of the proposed antenna to reveal the intrinsic behavior of the dielectric resonator. It is found that the quasi-isotropic radiation pattern can be achieved by combining HDRA’s TE111 sinϕ mode which radiates like a magnetic dipole and a small ground plane’s TM10 mode that radiates like an electric dipole. In order to reach the requirement of 5.8 GHz in ISM, a ceramic hemispherical dielectric resonator with dielectric constant of 21.984 is investigated. The radius of the hemisphere is set to 5.35 mm. In free space, the measurement results show that the proposed antenna achieves 3.25% bandwidth, 86% maximum efficiency, and 7.2 dB gain deviation. The antenna is also measured in pork to approximate human body environment. The measurement results demonstrate that the antenna achieves 3.20% bandwidth, 8.15% maximum efficiency, and 9.0 dB gain deviation. Accordingly, the proposed antenna is suitable for WCE application at 5.8 GHz ISM standard. © 2021, Electromagnetics Academy. All rights reserved.