Reserch On The Multi-frequency Feed Antenna In Remote Sensing Detection

At present, in the process of satellite remote sensing detection field, the requirement of remote sensing antenna is also constantly rising up, multi-band multiplexing,function integration and structure miniaturization antenna get more attention than before. A multi-band antenna can make full use of remote sensing satellite spectrum resources and reduce cost. In the field of remote sensing area,multi-band miniaturization antenna has become a hot topic research. Aiming at this question,this article uses Model Matching Method to analysis and design an feed antenna structure that can be used in six bands(89/36.5/22.3/18.6/10.63/6.6GHz).First of all, considering about the higher mode’s influence to the waveguide structure’s performance, this paper decides to use Model Matching Method to theoretically analysis some typical waveguide structure in order to give the theory foundation to the waveguide structure designment and parameter optimization. And then,considering the more structure parameters of the waveguide structure, such as multiple diaphragm filter,because they have too many parameters needing a lot of simulation time so as to have a bad efficient. So this paper decided to use MATLAB software to analysis them, and use Genetic Algorithm to write an optimizer to get the best parameters, then take these parameters into HFSS electromagnetic simulation software to build the model and simulate to verify the feasibility of the method.Secondly, on account of the requirement of a series of the waveguide structures which are used for multi-band feed, such as ortho-mode transducer, duplexer,rectangular waveguide-circular waveguide T junction, rectangular waveguide-coaxial waveguide T junction, coaxial turnstile, curved staircase waveguide,splitter, this paper will respectively build model and optimize. Finally put all those structure together by mean of the public port to achieve no consumption of cascade, creating three relative and independent structure of each other,89 GHz circular waveguide transmission structures,36.5/22.3/18.6GHz tri-band OMT coaxial waveguide transmission structures and 10.63/6.6GHz dual-band OMT coaxial waveguide transmission structures,the three structures are put together by coaxial nesting method to achieve the function of six-band transmission.Then starting designing the feed horn antenna segment, considering about the corrugated horn antenna structure is complex, differently to process as well as the cost is high. This paper decided to use dielectric loaded horn which has the same performance as the corrugated horn to be the feed antenna structure.Dielectric loaded horn can create an axisymmetric directivity diagram by transfering HE11 mixed model wave and has low side-lobe as well as low cross polarization. The structure of the multi-band feed is same with the structure of the feed waveguide.It’s divided three parts,89 GHz conical horn,36.5/22.3/18.6GHz tri-band dielectric loaded horn anddual-band dielectric loaded horn.On the account of the large difference of these three structures’ size,we can ignore the coupling influence.At last,the feed waveguide structure and the feed horn antenna are connected together.The feed is completed so far and it will achieve the goal of transmitting six-band cross polarization wave.