Directional High Gain Liquid Antenna Using Tumbler-Like Dielectric Resonator for Wireless Capsule Endoscopes System

This paper proposes a directional antenna applied to a wireless capsule endoscope (WCE) system using a tumbler-like liquid dielectric resonator. The liquid dielectric resonator antenna (LDRA) is composed of an upper zone comprising water and a lower zone consisting of the Galinstan liquid metal, and it is stored in a spherical container fabricated using 3D printing technology. The attitude-independent characteristic of the proposed antenna is reached by combining the “tumbler principle” with the hemispherical DRA theory and using appropriate liquid materials. Therefore, this method can provide directional radiation performance to significantly improve the gain of the antenna without affecting the normal communication of the WCE system in the human body. Water with a high dielectric constant is used as the liquid dielectric material in order to miniaturize the antenna. The experimental results demonstrate that the working band of the proposed antenna, which is referred to as TLDRA, is 5.72-5.88 GHz (S11 < -10 dB), with a maximum gain of -12.6 dBi, and thus it covers the Industrial, Scientific, and Medical (ISM) band (5.725-5.875 GHz). TLDRA has a small size and high gain, and therefore it has great potential in the WCE system applications.