Research On Retrodirective Antenna Array

With the rapid increase in the amount of the mobile communications subscribers these years and the limited spectrum resources, there is a serious need for modern wireless communication antennas with the features of low-cost, high gain and the capabilities of adaptive beam tracking. Retrodirective antenna arrays have the characteristic of reflecting an incident wave toward the source direction without any prior information on the source location and the complex digital signal processing. It is based on phase conjugation techniques with fast-track features and high cost performance ratio. It can be applied widely in the field of communications and radar.The dissertation summarized the study of current conditions and research methods of the retrodirective antenna array, analyzed and discussed the advantages and disadvantages of a variety of different ways for its implementation, and theoretically specified the retrodirective antennas and their related issues.Retrodirective antennas are merely qualitatively described in most literatures, however, in this dissertation, the realization conditions of retrodirective function are derived from the general antenna array models, which are the phase conjugation conditions. The generalized phase-conjugate conditions and generalized phase-conjugate wave are both firstly proposed in this dissertation. We also theoretically proved the existence of the phase-conjugate wave and the peculiar character of retrodirective antenna array. The three main types of the realization of the retrodirectivity and their advantages and disadvantages are discussed. The expressions of monostatic and bistatic RCS are theoretically derived. The noise characteristic of retrodirective array is studiedVanAtta array is the first array to realize retrodirectivity. For it is merely qualitatively described in other literatures, we discuss the theoretical research for VanAtta array in detail, and yield the mathematical expressions for the scattered field of passive and active VanAtta linear array, and active VanAtta planar array. The reflection of antenna element and the influence to power amplifier of its circulator isolation are studied. The characteristics of scattered field for VanAtta antenna array are analyzed, and its automatic beam tracking capability is verified by system simulation. With the applications of high altitude platforms, the non-cross-connect planar VanAtta array layout is given, and the length of transmission line and the relationship between loss and the array dimensions are discussedFor retrodirective array based on heterodyne mixer technology, the mathematical expressions for its retrodirective field considering mutual coupling and RF leakage are given. The concept of leakage coefficient is first proposed, and discussed the RF leakage coefficient on the impact of amplitude, phase and beam point errors.The dual-polarized and high isolated antenna is needed for retrodirective antenna array. With the moments method we analyzed and designed a dual-polarized high-gain broadband microstrip antenna with H-aperture-coupled feed. Based on series distribution loading Schekunoff integral equation, the general consecutive impedance load profile with arbitrary current distribution is realized. Based on Wu-King profile, we realized a high efficient profile of impedance loading profile, corrected the Wu-King expanded factor, and give the best theoretical design curve. We theoretically researched and simulated the broadband and high efficiency characteristics of the loading profile.In retrodirective communication system, different architecture leads to different functions and performances. One of the most important indicators of retrodirective performance is beam pointing error. The paper firstly summarizes various retrodirective system architecture available, and studies the relationship between beam pointing error and array dimensions, element antenna, RF leakage, frequency offset, and Doppler frequency shift, providing a theory basis for system design. On this basis, we proposed and designed a retrodirective communication system working in the C-band, and give the system performance by theoretical simulation.The dumbbell-shape defected ground structure (DGS) is finally studied for microstrip filter in retrodirective communication system. We first improved the extraction method of LCR equivalent circuit. On this method, we firstly proposed the synthesis and rapid analysis method of dumbbell-shape DGS, giving the process of analysis and synthesis and the theoretical basis. The dissertation also firstly proposed a new extracting method for periodic dumbbell-shape DGS. Simulations and measured results proved the validity of the synthesis method and the extracting method. Finally, we proposed an improving design method for split ring resonator band-pass filter, improving the band characteristics and depth of transmission zeros. The combination of split ring resonator band-pass filter and periodic DGS leads to a three octave 30dB stopband, effectively limiting the high harmonics.