Characteristics Of Multi-Frequency Feed Antenna Based On Mode Matching

In recent years,more and more horn antennas have been used in the field of satellite communications because of their high communication stability,low insertion loss,and ability to carry large power capacity.The traditional corrugated horn structure is relatively simple,and the mouth-surface field has a relatively regular structure.Such an antenna structure has a relatively simple radiation field expression.However,for a complex antenna structure,it is often difficult to design its structure directly,and its structure needs to be designed through some numerical calculation methods.At present,communication technology has developed very well.Those traditional antenna design models are far from meeting the needs of modern communications.In this way,people have proposed the use of numerical calculation techniques to design and optimize the antenna structure,which can be more efficient..This paper makes a detailed analysis of satellite traffic systems that are increasingly in demand in the military and civilian areas.Combined with the application background and theoretical analysis of modern antennas,this paper proposes a new set of numerical methods for designing and optimizing antennas.Including the detailed analysis of common non-uniform waveguide junctions,coaxial structures and hybrid waveguide structures,theoretical modeling and numerical calculations,the internal transmission losses,impedance characteristics and radiation characteristics of the antenna are obtained.Improve the accuracy and speed of the design.This paper first introduces the origins of various electromagnetic field component expressions in each coordinate system,which leads to a pattern matching method for the discontinuous structure of the waveguide inside the metal cavity.Through rigorous mathematical derivation,the intrinsic characteristics of each discrete waveguide junction are obtained.Pattern mutual coupling coefficient matrix.A realistic antenna structure is equivalent to a multimode circuit model so that an algorithm can be used to design and optimize.This paper introduces the numerical calculation method of the metal waveguide port.The spherical wave expansion method is a common calculation method for the waveguide surface.The S-parameter inside the metal conductor is obtained by the pattern matching method,and then the S-parameter of the antenna radiation surface is obtained by the spherical wave expansion method,so that the complete S-parameter of the antenna is obtained.When the mode of the feed port of the antenna is determined,the amount of electromagnetic radiation at any position in the entire space can be obtained.The isolation between ports and the reflection coefficient of each port can also be calculated accordingly.In order to verify the accuracy of the numerical algorithm,two Ku/Ka-band dual-frequency feed antennas that can be designed using numerical algorithms are designed,and a new type of medium-loaded dual-frequency feed antenna is proposed to ensure its goodness.The radiation characteristics.The feed antenna is mainly used for the feed of the reflector antenna of the satellite ground station.The size of its structure is strictly limited,which can effectively improve the radiation efficiency.Both feed antennas can achieve good port reflection coefficients,low crosspolarization levels,relatively stable phase centers,and ideal rotational symmetry patterns.The principle is to make use of the pattern matching method to construct the horn that needs to be designed into an ideal mathematical model.Among them,many structural parameters need to be optimized.In this way,its ideal mathematical model has become a multi-objective function,combined with the genetic algorithm to give initial values,iterates,set the number of iterations,cutoff frequency,the number of models to be considered,etc.,run through MATLAB,until the optimization of the target results convergence.The resulting data is the optimized result of the antenna.Comparing with full-wave simulation software such as HFSS and CST,it can verify the algorithm's extremely high calculation efficiency and high numerical accuracy.This method has certain versatility and can be designed and optimized for some rotationally symmetric structures.In addition,the analysis of the structure loaded by the dielectric rod can also be performed.Mainly for a complex structure of the feed horn system,can effectively establish a mathematical model to achieve multi-objective and multimode system optimization.Sufficient accuracy can be guaranteed.Embodies the high efficiency of numerical calculations.At the end of this paper,in order to solve the inefficiency of traditional full-wave simulation technology in designing and optimizing multiple indexes,a complete optimization design algorithm is proposed systematically and applied in some common practical contexts.