10.1 Introduction

Microwave oscillators form an important part of all microwave systems such as those used in radar, communication links, navigation, and electronic warfare (EW). With the rapid advancement of technology there has been an increasing need for better performance of oscillators. The emphasis has been on low noise, small size, low cost, high efficiency, high temperature stability, and reliability. The transistor dielectric resonator oscillator (TDRO) presents an interesting solution as a quality oscillator for fixed frequency or narrowband tunable oscillators. The present commercially available gallium arsenide field effect transistor (GaAs FET) can be used as the active device in oscillators for the entire microwave frequency range from 1 to 30 GHz. With the advent of temperature stable materials, the dielectric resonator has emerged as a high Q, low loss, and conveniently sized element for applications in various microwave integrated circuits (MICs) for the entire microwave frequency range [1].

This chapter starts with the characterization of the dielectric resonator and the transistor. The oscillation conditions and the design of a TDRO using 3-port scattering matrix parameters (S-parameters) are then described. Temperature stability and the tunability of the TDRO are presented, followed by the measurement of TDRO characteristics.

10.2 S-parameter Characterization of a Microstrip-Coupled Dielectric Resonator

The dielectric resonator is coupled to a microstrip line for applications in different MIC's like filters, discriminators, oscillators, etc. The commonly used configuration is shown in Fig. 10.1. The dielectric resonator placed near the microstrip line on the substrate is enclosed in a...