Octafilar Helical Antenna for Circular Polarization Wireless Capsule Endoscopy Applications

This paper introduces a proposed design of a circularly polarized quadfilar or octafilar helical antenna (QFHA or OFHA) dedicated for wireless in-body capsule endoscopy applications at 2.4 GHz. The use of a circularly polarized antenna permits a freedom in capsule orientation during endoscopy process. A multi-layered cylindrical model and homogenous cubic model for the human body tissues are studied and compared. The radiation characteristics of the QFHA and OFHA are encapsulated and placed inside the human model. Both the QFHA and the OFHA in capsule module are designed to resonate at 2.4 GHz with an impedance matching wide bandwidth of 125 MHz. The effect of the capsule ordination on the performance of the endoscopy process is studied. The response of the OFHA with and without capsulation is studied and introduced. The electrical length of an implantable antenna increases due to the high permittivity of the surrounding body tissues. The radiation characteristics of the QFHA and OFHA antennas in different cases are fully analysed and investigated using the finite integral technique.