Compact and Broadband Printed Antennas

Abstract

In recent years device industries has shown substantial interest in low-profile and conformal circuits to meet the requirements of evolving wireless technologies and standards. There is an increasing interest towards development of integrated/on chip antennas especially for wireless devices. Achieving broad impedance and radiation bandwidth from a compact antenna has been a challenging task. There are several research groups who pioneered in development of the compact broadband antennas for wireless devices. This chapter discusses techniques used to design compact and broadband antennas. The design techniques discussed in this chapter includes design of broadband printed microstrip and slot antennas, Metamaterial inspired antennas, Antennas integrated with periodic structures, and composition of resonators for compact antenna design. Some of the examples presented in this chapter also pertains to the millimeter wave antennas where metamaterial inspired configurations are used. Here, the term broadband antenna is associated with those antennas which provides consistent impedance bandwidth i.e., the return loss <10 dB (Voltage standing wave ratio-VSWR <2) and consistent radiation bandwidth i.e., characteristics such as gain, efficiency and radiation pattern are consistent for a given impedance bandwidth. Most of the antennas discussed here are printed antenna i.e., they are printed on a low-loss dielectric substrate with specific permittivity. As the value of substrate’s permittivity contributes towards antenna design, its selection for the antenna design is done based on end use/application of the antenna.