Broadband phase shifter design for phased array radar systems

Abstract

Phase shifters are one of the key control components in phased array radar systems to electrically shape and steer the antenna beam. In modern radar applications where multi-function capability and communication security are required, broadband phase shifters are essential. This work mainly aims to improve the conventional phase shifters and explore novel topologies for broadband and high performance designs. One set of general formulas, which includes the formulas of conventional method as a special case, is found for the high-pass/low-pass phase shifter design, and closed-form equations for bandwidth enhanced and dual-band loaded-line phase shifter are provided. Several novel topologies using a phase slope alignment concept are also proposed, where trade-offs between phase error, return loss and bandwidth are possible. Based on this method, an octave band phase shifter with an RMS phase error of 3.6? and a return loss larger than 15 dB (|S11|<-15dB) was designed. Further study of the all-pass phase shifter is also presented to establish multi-octave band performance. As a conclusion, a phase shifter guide table is built for designers? reference. Other novel microwave components associated with the insertion phase, e.g. broadband quadrature and dual-band power dividers are also covered.