A Design Approach for in-Body Antennas for Animal Biotelemetry Applications

Boluses with biotelemetry capabilities enable wire- less monitoring of animal physiological data (e.g., ruminal temperature, pH). These devices rely on antennas to interface with external receivers. Existing antennas typically provide a short-range (1–2 m) communication, which can be improved by addressing the radiation efficiency. In this paper, a novel design approach for in-body antennas for animal biotelemetry applications is presented. The optimal frequency band is studied prior to the design of the antenna based on the dielectric measurements of the antenna environment. A demonstrator conformal patch antenna is proposed for the 434 MHz ISM band. The performance of the antenna is simulated in phantoms with cow’s rumen fluid electromagnetic properties. The antenna is integrated in a bolus with 13 cm length and 1.5 cm radius. The proposed antenna has a gain of –20.1 dBi and the radiation efficiency of 0.53% in a spherical phantom with a diameter of 200 mm.