The Miniaturization Of Spiral Antenna And The Research On Conformal Array Antenna On Cone Platform

The development of the spiral antenna is very mature, and the research of the antenna element and its feed system is common. However, the simulation of the whole system with reflecting cavity is very few, and it has no good matching effect and the radiation characteristic is poor. The research of conformal array is hot but difficult. Only the professional sector can provide the computer resources needed for its simulation. The calculation method and the radiation rules of conformal array antennas is not perfect. So the research on the radiation characteristics of conformal array antennas is of great significance to the development of conformal arrays.In this paper, we first introduce the theory of planar spiral antenna and conformal antenna array. The planar equiangular spiral antenna with the bandwidth of 8-18 GHz which covered X band and Ku band is designed. The composite structure and the crank arms are used to carry out the miniaturization design. The antenna with a diameter of 36 mm in the same frequency band narrowed to only 20 mm. The microstrip balun is designed to achieve the transformation of the balanced antenna to the unbalanced coaxial line and the transformation of impedance. In order to realize the high gain of the antenna, a conical reflector is designed. The unidirectional radiation of the antenna is realized and the gain of the antenna is increased by about 3 d B while maintaining the bandwidth. The whole structures of antenna, the balun and the reflector are simulated and optimized. The VSWR of the antenna system is less than 2.5 in the whole band, and the radiation of the antenna is improved obviously.The conformal antenna array is studied in this paper synchronously. We put the little antennas on the cone with the largest area so the conformal antennas can be simulated. In order to realize the gain of 15 d B, we design a conformal array of 4×5 at first. And I use the 1×4 array parallel to the cone to verify the conformal effect. On both sides of the antenna deflection is too oblique resulting in the split of the direction graph. Then 1×3 array parallel to the cone is simulated. We regard it as an unit and array synthesis is carried out along the direction of the cone. Thus, the radiation characteristics of conformal array are obtained. The gain of the array after adding the reflecting cavity is sufficient to meet the requirement of 15 d B and the sidelobe level is less than-13 d B. At the same time, the simulation resource is greatly saved, which provides a good idea for the research of conformal array.