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Investigations of High-Power High-Gainradial Line Helical Array Antenna

Author: ZhangJianZuo
Tutor: LiuQingXiang
School: Southwest Jiaotong University
Course: Electromagnetic Field and Microwave Technology
Keywords: high-power microwave radial line helical antenna backed cavity radome array antenna coupled probe circularly-polarized power divider
CLC: TN823.31
Type: PhD thesis
Year: 2011
Downloads: 200
Quote: 1
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Abstract

The high power microwave (HPM) radiation system is terminal of HPM system, and efficiency of the whole system should be reflected by radiation system eventually, so more attention has been progressively paid to the function of HPM radiation system with the development of high power microwave technology, and HPM radiation techniques have become one of the important research content of HPM technology.Although many of the traditional microwave radiation technology has matured, the inherent characteristics of high power microwave brought many new problems, which make the traditional microwave radiation technology cannot be used in high power microwave directly. These new problems include that: high power handling capacity, the directional radiation of axisymmetric mode, high efficience, compact structure and so on. Therefore, many researches have been made at home and abroad, and such HPM antennas as mode converter with radiant horn, Vlasov antenna and mode-transducing antenna (like COBRA antenna, etc.), array antenna have been put forward. However, they are subject to some disadvantages more or less, and they can not perfectly meet the requirements of HPM system that become greater. The shortage of existing high power microwave radiation technology make us to adopt new techniques, new methods and explore new type of high power microwave antennas, which will promote the development of high power microwave radiation technology, also adapte with the fast development of high power microwave technology.In order to overcome the challenge of HPM radiation system, this paper puts forward and study a novel high power microwave radiation antenna-high-power high-gain radial line array antenna.The design thought of high-power high-gain radial line array antenna is that: adopting several subarrays to form a high-gain array and each subarray is feeded by high power mutil-way power divider; the subarray adopt high power circularly-polarized antenna as radiation unit, uses the radial line as feeding waveguide, and applies coupling probes to feed energy from radial line to unit antenna; Finally using antenna radome to make the whole array at vacuum state and reaching comparatively high power-handling capacity. Theoretical principle related to the antenna are summarized and ameliorated systemically based upon the basic principle of high-power high-gain radial line array antenna.Base on the design thought of high-power high-gain radial line array antenna, the paper focuses on the key component of the array antenna-high power unit antenna. First, the paper gives the description of radiation mechanism and far-field radiation characteristic of cylinder helical antenna, analyzes the physical foundation of axial mode helical antenna as phase shifter. Second, proposeing a vacuum sealed scheme of short helical antenna based on the unit cell, which solves the sealed problem of high-gain array. Third, analyzing the power-handling capacity of antenna in the vacuum sealed scheme, and improving the performance of the unit antenna beased on the initial design. Finally, analyzing the mutual coupling between the two novel high-power unit antennas, and experiment on the vacuum properties of the sealed scheme, which verify the feasibility of the scheme.Then the paper studies the high-power radial line rectangular subarray. The high-gain array antenna can be formed by combination of several subarrays, and the performance of which can depend largely on the performance of the subarray. First, the paper describes the design of16-element rectangular lattice subarray, which use the novel high-power unit antenna as its radiation unit. The experiment result verifies the feasibility of the unit antenna. Then, research on the triangular lattice radial line subarray, which can save16%numbers of unit antenna compare to the rectangular lattice subarray. With the same unit antenna, the paper research on the3-element,4-element,6-element and8-element subarray, analyzing the matching condition and polarization characteristic, also realizing the methods to improve the performance of subarray. Finially, designing on12-element triangular lattice radial line subarray, and the feasibility of the subarray is verified by experiment.Afterwards, the paper studies the high-power muti-way power divider, which is used to feed the subarray. The key questions include that:high-power handling capacity, muti-way equal magnitude and phase output and equal patch feeding. In order to satisfy this requirement, the paper discusses two schemes. The first scheme is realized by radial line power divider and coaxial connection waveguide. Because of the requirements on equal patch feeding, which causes the coaxial connection waveguide complex and longer, also affects the high efficience and compact sturucture of the whole system. The second scheme is composed of coaxial-4way rectangular waveguide, HT waveguide and R-C converter, the power divider is in the same plane, so it have the advangates of short axial length, compact structure, alao meet the requirements on equal patch feeding, and the experiment verify the feasibility of the second schemes.At last, the high-power high-gain radial line array antenna is integrated and tested, which adopt16number of16-element subarray to form256units array antenna, and uses the second schemes of high-power16-way power divider to feed the subarray. The experiment and analysis realize that: the antenna gain is about30dB, axial radio is about ldB and power-handling capacity exceeds1GW.

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