High Order Harmonic Oscillators in Microwave and Millimeter-wave ...

Preface
Wireless and mobile communications such as W-CMA and LTE, as well as the wireless
sensors and radar systems, have been attractive applications in microwave and millimeterwave.
The fields are not only wireless communications but also astronomy and medical
fields. Moreover a wireless power transfer will be realized in near future. Therefore,
microwave and millimeter-wave circuits will be important to advance these technologies.
An oscillator is the most important component because it is an essential source of the
RF signal. Especially, in the wireless communication systems, the performance of the
oscillator decides the quality of the communication systems. The oscillator is required for
all the transmitters and receivers. However, the oscillators in high frequency bands have
some practical problems such as the output power, phase noise, stability and cost.
A harmonic oscillator is one of the effective solutions for these problems . In this
study, a Selectively Enhanced Harmonic Oscillator (SEHO) is presented. High frequency
millimeter-wave signal can be generated by using inexpensive microwave devices. Based
on the coherent field of the line resonator, several SEHOs are proposed. The important
technical concepts of this study are as follows.
(1) Enhance the desired resonant field in a line resonator.
(2) Selectively extract the desired harmonic signal from the resonant field.
All researches described in this dissertation are based on the concept.
Chapter 2 explains the oscillator theory. At first, basic oscillator principles of a feedback
oscillator and a negative resistance oscillator are explained. Then, a harmonic oscillator
which is the core technology of this study is mentioned. A structure and the principle of
the basic push-push oscillator is explained. Then, a simple structure push-push oscillator
utilizing the electromagnetic resonant field is introduced.
ii