Compact multiband antennas for wireless systems

The research work to be presented focuses on the study of multiband antennas for wireless indoor communications and wearable transceivers. An introduction to the essential antenna parameters and the theory behind the electromagnetic simulators used for this research sets the background necessary for understanding the procedure used when designing and measuring antennas. A study of the characteristics of textile materials at microwave frequencies using non-resonant transmission methods is later performed. The basis of small antenna design by top loading and the design of the Planar Inverted F Antenna is also covered.

The main research work is divided into two parts. The first part investigates antennas for mobile and wireless indoor communications networks. The antennas are intended for Distributed Antenna Units to be located in buildings. A dual band Planar Inverted F antenna previously developed at the University of Kent is chosen as the prototype to achieve multiband and broadband operations. A parasitic resonator on the ground plane and side resonators are introduced in a study where additional bands are added. The derivation of equivalent function planar antennas from three dimensional multiband PIFAs is also covered.

The second part of the work focus on antennas for wearable applications. The antennas are intended for WLAN on-body communication networks. A novel approach is taken by using metallic button structures to create wearable antennas. Dual frequency band operation is achieved on the button structures by adding a metallic plate on the top of the antenna and a cylindrical via connector. Miniaturization techniques are later applied to the button structure to reduce the size of the antenna while maintaining a match at the 2.4GPIz and 5 GHz wireless bands.