DESIGN OF WIDEBAND MONOPOLE ANTENNA LOADED WITH SMALL SPIRAL FOR USING IN WIRELESS CAPSULE ENDOSCOPY SYSTEMS

In this paper, a new antenna is designed in order to use in the wireless capsule endoscopy (WCE) system. This antenna consists of two parts; the small monopole part and the small spiral. Having the omnidirectional radiation pattern for covering the stochastic motions of the capsule into gastrointestinal and also, appropriate gain and wide bandwidth to achieve high resolution images must be considered in designing procedure. In this design, a good radiation pattern is obtained from small monopole, and using the spiral structure leads to an appropriate wide bandwidth and a miniaturized antenna. By simulating this antenna in the human body environment and considering four different body tissues and their results, the antenna has the bandwidth of 360MHz (39.3% relative bandwidth) at 928MHz center frequency which covers the ISM band (868.0–868.6 MHz and 902.8 to 928.0MHz). The radiation pattern of the antenna is omnidirectional. The maximum gain of the designed antenna is −23 dB, over the frequency band that is suitable for using as a transmitter antenna in the WCEs.