The Study Of Airborne Antenna And The Coupled Field Of Diplexer For Ku Band

Combing with the scientific research projects, an airborne antenna is designed in the dissertation and the coupled field of a diplexer for Ku band is analyzed. The concept of this dissertation can be divided into two parts: in the first part, an unidirectional airborne antenna has been analyzed and simulated, and a prototype has been fabricated and tested, the airborne antenna is verified with simulation and test; the coupled field of a diplexer for Ku band is analyzed in the second part, according to the simulated results, the relationship between structure distortion on the surface of waveguide and the electrical performance has been studied, and the diplexer has been tested.The elementary knowledge of airborne antenna is introduced firstly, which consists of the characteristic parameter, the general design requirements, the classification and the electromagnetic compatibility of the airborne antennas. Basis of this, two design methods about the airborne antenna, which works in the frequency range of 5.9~7.3GHz, are proposed. Planar slot antenna is proposed firstly, simplifying the surface of the airplane to be a large mental plane which inclines against the ground plane. Then proposed a monopole antenna which is placed in a cavitary, and discussing the various characters of the antenna when the electrical size of the airplane is changing from small to large. The simulated results of the two antennas are analyzed, and based on the second antenna design method; the engineering prototype of antenna is fabricated and tested. The measured results indicate that in the frequency range of 6.13GHz to 6.96GHz, the VSWR of the monopole antenna, which is placed in a cavitary, is less than 2, and the peak gain of the antenna is more than 1dB. The non-circularities of the H-plane Omni-directional pattern is less than 8dB and the measured results show good agreement with the simulated results, means that the design is valid.Secondly, basic theory of the waveguide transmission is introduced in this dissertation, and based on that, a diplexer for Ku band is discussed, and the relationship between structure distortion on the surface of waveguide and the electrical performance has been studied, and then get the limit of the distortion. The measured results of the sample diplexer are given finally.