Wireless Body Area Networks for healthcare and medical purposes require wearable transceivers and antennas for 24hour monitoring. The fabrication of miniature electronic devices used for wireless connectivity is of great commercial interest. This has resulted in many compact wireless devices that are either implanted inside the body or placed on the skin surface. The thesis reports the interaction between the human body and wireless technologies including electromagnetic wave propagation, wireless channel modelling, and wearable antenna design for on-body to in-body applications. This research contributes to a wider project seeking to improve the location accuracy of an ingested radio transmitter inside the human abdomen by monitoring the signal on the torso surface using an array of electric field sensors. Three-dimensional software (CST microwave studio) was used for electromagnetic modelling to develop a biomedical tissue model, and to assist in the design of an array of receivers for tracking the radio transmitter inside the gastrointestinal tract. The work on this project focused on the following aspects:

1. The design, fabrication and testing of a UHF small cavity-backed receiver antenna, and a design of a wireless transmitter antenna at 2.45GHz Industrial, Scientific, and Medical frequency band to measure the effect of human tissue on surface field strength measurements.
2. The effect of coupling between two identical human torso body-worn antennas and the effect of an external radio source at 2.45GHz on the surface field strength measurements.
3. Measurements of the E-field distribution on the skin surface in in-vivo and ex-vivo experiments using animal and human subjects. The outcome of this project concluded that a cavity-backed slot antenna is sufficiently small and reliable for electric field strength measurements on the human body from an internal radio transmitter. This allows the accurate location of the transmitter passing through the gut from surface measurements over the time. This work will be a useful change for future healthcare.