A Conformal UWB Dual-Polarized Antenna for Wireless Capsule Endoscope Systems

A conformal ultrawideband (UWB) dual-polarized capsule antenna is designed for ingestible wireless capsule endoscope (WCE) systems. To the best of our knowledge, this is the first time to study the UWB dual-polarized antenna for a capsule endoscope system. Dual polarization is realized by a step-shaped monopole and an irregular rectangular loop antenna, which are printed on the top and bottom side of the dielectric substrate, separately. The simulated antenna has very wide -10 dB impedance bandwidth of 2.15-14.75 GHz, which can cover 2.4-2.48 GHz, 5.725-5.875 GHz Industrial, Scientific, and Medical (ISM) band, 3.5-4.5 GHz impulse radio UWB (IR-UWB) and 3.1-10.6 GHz UWB. Moreover, because of the orthogonally polarized waves generated by two types of antennas, the simulated isolation between them is better than 40 dB in the whole band. Considering the application of the antenna in the wireless body area network system, this design focuses on 1-7 GHz frequency band, especially 4 GHz IR-UWB. An antenna prototype is fabricated and measured, and the measured S-parameters and radiation pattern demonstrate a reasonable agreement with the simulation results. Furthermore, specific absorption rate and link budget of the antenna are analyzed.