Wideband two-dimensional and multiple beam phased arrays and microwave applications using piezoelectric transducers

摘要

Modern satellite, wireless communication, and radar systems often demandwideband performance for multi-channel operation and the ability to steer multiplebeams for multiple moving targets. This dissertation covers a variety of topics to designlow-cost and wideband antenna systems. The main areas of study are microwave devicescontrolled piezoelectric transducers (PETs) and wideband baluns and balancedmicrowave circuits using parallel-strip lines. Some focus has also been given to thedesign of Rotman lens for multiple beam generation and Vivaldi antenna arrays forwideband two-dimensional scanning.The dielectric perturbation technique controlled by PET is introduced to design awideband phase shifter and a QPSK modulator, and to tune the resonant frequency of aslot dipole. The designed PET-controlled phase shifters are used for beam steering in adual beam phased array using a bidirectional feeding scheme and a five-beam phasedarray using a microstrip Rotman lens.Vivaldi-type antennas are commonly used to achieve wideband performance. Verywideband performance can be achieved using an antipodal tapered slot antenna becauseof its inherent simple wideband transition from microstrip line to parallel-strip line. Anantipodal tapered slot antenna and a phased array are designed to span 10 to 35 GHz. Inaddition, a 4??4 two-dimensional antenna array is designed using wideband antipodaltapered slot antennas, and two sets of PET-controlled phase shifters for E- and H-planescanning are fabricated to steer the beam. As a microwave system using widebandantenna array, a new low-cost and wideband phased array radar is developed using amodulated pulse over 8 to 20 GHz band.The double-sided parallel-strip line as a balanced line is presented. The parallelstripline offers much flexibility for microwave circuit designs. This transmission linemakes it possible to realize a low impedance line and allows the design of a compactwideband balun and junction. Wideband transitions (or baluns) from parallel-strip line tomicrostrip line, a typical unbalanced transmission line, are realized to cover severaloctave bandwidth. Balanced microwave filters and a hybrid coupler are developed usingthe parallel-strip line.