Investigation, design and fabrication small tunable and reconfigurable antennas for 4G handsets

Abstract

The tremendous advancement in general communication technologies together with the growing on consumer have driven strong demands for small handsets but applicable for multiband on a single device. A recent trend shows that modern mobile handsets are required to operate at multiple frequency bands and to be able to cover various commercial communication services. The requirement of compact size, light weight, reduced height, and applicable of multifunctional handsets puts more stringent requirements on the antenna design and more challenging for antenna designers. Antenna is one of important elements and plays a significant role in wireless communication systems. Thanks to the development of modern integrated circuit technology, the size and weight of mobile handsets have been rapidly reduced. Generally, though broadband and multiband antenna designers have achieved advantages to reach the above target, the number of wireless communication systems is increasing dramatically, meaning that adjacent interference signals between those systems for the broadband and/or multiband antennas are also increasing. It is desired that the antenna can be tunable in active ways to meet the requirements of covering multiband individually or simultaneously while being able to minimize or eliminate unwanted radio frequency interferences. With advances in high density radio frequency and microwave circuit packaging, integrated components for antennas have been studied widely for tuning or reconfiguring purposes. It is shown that a single well-designed antenna having efficient bandwidth and enough tuning range can be used for different operating frequency bands. This thesis contributes another effort for tunable/reconfigurable antennas. In scientific literatures, several techniques are proposed for tunable and reconfigurable antennas such as RF switches, MEMS switches, PIN diodes, varactor diodes, and screw. We review the advantages, disadvantages and tuning/reconfiguring mechani...