Novel Approaches to the Design of Phased Array Antennas.

Abstract

This dissertation presents three new approaches to the design of phased array antennas in order to reduce their complexity. The first approach is based on extended resonance technique which, unlike conventional phased array designs, achieves power dividing and phase shifting tasks within a single circuit. A new extended resonance circuit is developed here that increases the maximum achievable scan angle by three times compared to the extended resonance phased array demonstrated previously. In order to expand the size of phased array, a new modular approach is used enabling a scalable design of extended resonance phased array for the first time. By applying heterodyne-mixing concept, a modular 24 GHz phased array has been demonstrated. The second approach presented in this dissertation is based on a bi-directional feeding method. A new phased array is designed based on this approach which demands less phase shift from phase shifters compared to any of common phased arrays. The new bi-directional phased array allows for beam steering using only a single control voltage. A general design procedure for a bidirectional N-element phased array feed network is presented for the first time which allows applying this approach to phased arrays with any number of antenna elements. Furthermore, a new, compact phase shifter is designed and utilized in the phased array. A 2.4 GHz bi-directional phased array has been designed and fabricated. Finally, the third approach described in the dissertation allows the phase progression across the antenna elements to be controlled by using a single phase shifter. Therefore, the number of phase shifters required in the phased array is substantially reduced compared to conventional phased array designs which require a separate phase shifter per each antenna element. A variable phase shift is achieved in this approach by vector summation of signals. The amplitude ratios of these vectors are adjusted to provide a linear phase progression. This approach is much simpler than the traditional Cartesian phase shifting scheme. A 2 GHz phased array designed based on this approach has been fabricated and tested.