A Planar Circularly Polarized Omni-directional Antenna for Capsule Endoscopy System

An planar circularly polarized omni-directional radiation antenna was rationally designed for wireless capsule endoscopy (WCE) in this paper. It can be used in the 2.45 GHz Industrial, Scientific and Medical (ISM) band (2.400–2.4835 GHz), and the antenna is designed to be compact and small in size, only $\pi \times 3^{2} \times 0.854 \mathrm{~mm}^{3}$. The designed antenna was simulated in Ansys HFSS and placed in the center of a $\mathbf{5 0} \times \mathbf{5 0} \times \mathbf{5 0} \mathrm{mm}^{\mathbf{3}}$ cube muscle tissue. The simulation results reveal that the proposed antenna impedance bandwidth $(\mathrm{BW})\left(\left|\mathrm{S}_{11}\right|\lt -10 \mathrm{~dB}\right)$ is 2.15 to 2.76 GHz, and the circular polarization bandwidth $(\mathrm{AR}\lt \mathbf{3 ~ d B})$ is 2.04 to 2.79 GHz, which has broad impedance bandwidth and circular polarization bandwidth. This antenna would be a promising candidate for the new capsule endoscope system.