Synthesized Transmission Lines

2Non‐Periodic Synthesized Transmission Lines for Circuit Miniaturization

C. W. Wang and T. G. Ma

2.1 Introduction

Non‐periodic synthesized transmission lines are realized by quasi‐lumped/lumped networks without any periodicity. In this sort of designs, the synthesized line is realized by a network associated with a significant amount of electrical length (i.e., phase delay). It can be directly applied as the building blocks of various passive microwave components. In general, the electrical length of a non‐periodic synthesized transmission line ranges from 30° to 90°, but can be even more. The common features of a non‐periodic synthesized transmission line include a high slow wave factor, impressive circuit miniaturization capability, and a simple synthesis approach. Nevertheless, they are also known to suffer from dispersive responses and higher parasitic loss. A compromise between the size reduction ratio, power dissipation and phase linearity is always required.

In this chapter, a number of non‐periodic synthesized transmission lines, using quasi‐lumped/lumped elements in microstrip and coplanar waveguide (CPW) forms on printed circuit boards (PCBs), are introduced using the design principles in Chapter 1. The synthesized microstrip/CPW lines are applied to a variety of microwave circuits with or without coupling between lines. Essential building blocks in the feeding network of a phased array, including the hybrid couplers and Butler matrix, are realized by synthesized microstrip ...