An ultra-wideband conformal meandered loop antenna for wireless capsule endoscopy

Abstract

This work presents an ultra-wideband conformal meandered loop antenna for wireless capsule endoscopy applications. The proposed antenna surrounds the outer wall of a capsule, so that the inner space can be used by a battery and other electrical and optical components. Fabricated on a flexible substrate, the antenna has a diameter of 10 mm and a height of 14 mm when wrapped around a cylindrical capsule. The antenna achieves an ultra-wide impedance bandwidth of 200 MHz-2.05 GHz (164% of the fractional bandwidth), which provides sufficient coverage for the medical implant communication service, MedRadio, and industrial-scientific-medical (ISM) bands. This antenna also ensures robustness to the detuning effect, which could be caused by the inner components of the capsule and the outer environment variations. The omnidirectional radiation pattern of the antenna is verified by simulations and measurements, and its maximum gain is -31.5 dBi. The fabricated antenna is successfully tested in an over-the-air wireless communication link, proving that the antenna can be instrumental in wireless capsule endoscopy applications.