Research On Miniaturized Broadband Directional Antenna Technology

This thesis studies the working principle and design method of log-periodic antenna and Vivaldi antenna.It focuses on the miniaturization and common aperture technology of ultra-wideband antenna.Based on the requirements,two miniaturized broadband directional antennas are designed to meet the requirements of technical indicators in different application scenarios.The main research content of this article includes three parts.1.Research and design of miniaturization of broadband directional antennas.According to the basic theory of log-period antenna and Vivaldi antenna,a log-period antenna and Vivaldi antenna are designed at the full size,and then the size of the antenna is reduced by using miniaturization techniques such as bending,loading,and meandering.It provides theoretical method support for the subsequent solution of key problems 2.Research and design of short-wave log-periodic array.Firstly,a full-size short-wave broadband log-periodic antenna is designed based on the working principle of log-periodic antenna.Then,in view of the limitation of the grating lobe suppression interval during phased array antenna azimuth scanning,the lateral size of the antenna is reduced by using a miniaturization technology,so that the proposed antenna achieves miniaturization and highly efficiency performance.Meanwhile,the lateral size of the antenna is smaller than the array pitch.Then the sky wave propagation theory explored the relationship between the elevation angle of the log period antenna beam and the height of the front and rear ends of the antenna.Finally,in order to realize the low side-lobe characteristics of the log-period array antenna,according to Taylor's comprehensive theoretical simulation design,the scanning of the wideband array low-side-lobe beam pointing at ± 40° is obtained.3.Design of multi-band miniaturized common aperture circular polarized antenna.Aiming at the antenna index requirements and accommodation space limitation,the structure and common aperture form of the three frequency band antennas L,SC and X are determined.Based on the working principle of the Vivaldi antenna,two miniaturized broadband Vivaldi antennas in the SC band and X band were designed.The integrated design of the two antennas stacked up and down was proposed to achieve dual-frequency common-aperture linear polarization and dual-frequency circular polarization.characteristic.Then,the corresponding broadband 3d B directional couplers of SC and X-band antennas are designed separately to achieve dual circular polarization feed.The gain of the antenna is greater than-5d Bic in the full-band ± 60° beam range.On the other hand,a four-inverted-F antenna for L-band antennas and a cylindrical conformal design for a one-fourth power division phase-shifting network is proposed,which achieves a wide beam characteristic with a gain greater than-8.5d Bic within a beam range of ± 90°.The three antennas are reasonably arranged and optimized under the common aperture,and are integrated with the feed network for simulation and optimization.The completed miniaturized multi-band common aperture wide beam circular polarization antenna has been tested.It has been shown that all the antenna indicators have met the design requirements.