| Summary: | 博士 === 國立臺灣大學 === 電信工程學研究所 === 91 === On the basis of the phase control ability of mutually coupled oscillator arrays, this dissertation investigates the novel applications for the high-frequency signal source and active antenna array systems. Both the theoretical analysis and the experimental implement are emphasized. The three new applications presented are an N-th harmonic oscillator, a retro-directive antenna array, and a beam-scanning and polarization-agile antenna array.
Firstly, in Chapter 3, the design concept of push-push oscillators is extended to triple-push, quadruple-push and hence N-push harmonic oscillators. Conventionally, this kind of problems is dealt with by linear mode analysis. The design principle in this dissertation is based on the injection-locking theory. The desired harmonic component can be selected by tuning the relative phases of the coupled oscillators and the conduction angles of voltage-clamping circuits. As the output phase-shifted signals of the coupled oscillators are properly shaped and combined, the desired harmonic components are constructively generated and lower-order harmonic components are suppressed. This structure can be viewed as the general case of push-push oscillators. Since the output power is combined in a passive circuit, it does not suffer from the power limit of the output device in the cascade structure. The circuit structure is presented and verified experimentally in second-harmonic, third-harmonic and fourth-harmonic oscillators.
In Chapter 4, a novel phase conjugation circuit and its application to retro-directive antennas are presented. The phase conjugation circuit uses a balanced circuit structure with subharmonically injection-locked self-oscillating mixers (SILSOMs) oscillating at ω. An input signal at ω/2 is converted to its conjugated signal with no external source required for LO signal pumping, and the output signal frequency is locked at the same frequency of the input signal. The developed phase conjugation circuit is implemented with active antennas to become a retro-directive antenna array. Both the theoretical and measured results of phase conjugation and retro-directive performance are presented.
Finally, a two-dimensional mutually coupled oscillator array is studied in Chapter 5 for the application of a beam-scanning and polarization-agile antenna array. In the antenna array design, the polarization agility is considered as one of the two dimensions (or y-direction) with the other dimension (or x-direction) for beam scanning of a two-dimensional oscillator array in x-y plane. The array radiation direction can be scanned for the selected polarization states including linearly polarized, left-hand and right-hand circularly polarized states. Well-defined phase differences among oscillators for beam scanning and polarization agility are given by utilizing the second-harmonic signal. The performances of polarization agility and beam scanning for a four-element antenna array are verified experimentally and shown to have the potential for adaptive antenna array applications.On the basis of the phase control ability of mutually coupled oscillator arrays, this dissertation investigates the novel applications for the high-frequency signal source and active antenna array systems. Both the theoretical analysis and the experimental implement are emphasized. The three new applications presented are an N-th harmonic oscillator, a retro-directive antenna array, and a beam-scanning and polarization-agile antenna array.
Firstly, in Chapter 3, the design concept of push-push oscillators is extended to triple-push, quadruple-push and hence N-push harmonic oscillators. Conventionally, this kind of problems is dealt with by linear mode analysis. The design principle in this dissertation is based on the injection-locking theory. The desired harmonic component can be selected by tuning the relative phases of the coupled oscillators and the conduction angles of voltage-clamping circuits. As the output phase-shifted signals of the coupled oscillators are properly shaped and combined, the desired harmonic components are constructively generated and lower-order harmonic components are suppressed. This structure can be viewed as the general case of push-push oscillators. Since the output power is combined in a passive circuit, it does not suffer from the power limit of the output device in the cascade structure. The circuit structure is presented and verified experimentally in second-harmonic, third-harmonic and fourth-harmonic oscillators.
In Chapter 4, a novel phase conjugation circuit and its application to retro-directive antennas are presented. The phase conjugation circuit uses a balanced circuit structure with subharmonically injection-locked self-oscillating mixers (SILSOMs) oscillating at ω. An input signal at ω/2 is converted to its conjugated signal with no external source required for LO signal pumping, and the output signal frequency is locked at the same frequency of the input signal. The developed phase conjugation circuit is implemented with active antennas to become a retro-directive antenna array. Both the theoretical and measured results of phase conjugation and retro-directive performance are presented.
Finally, a two-dimensional mutually coupled oscillator array is studied in Chapter 5 for the application of a beam-scanning and polarization-agile antenna array. In the antenna array design, the polarization agility is considered as one of the two dimensions (or y-direction) with the other dimension (or x-direction) for beam scanning of a two-dimensional oscillator array in x-y plane. The array radiation direction can be scanned for the selected polarization states including linearly polarized, left-hand and right-hand circularly polarized states. Well-defined phase differences among oscillators for beam scanning and polarization agility are given by utilizing the second-harmonic signal. The performances of polarization agility and beam scanning for a four-element antenna array are verified experimentally and shown to have the potential for adaptive antenna array applications.
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