Research And Design Of Vehicle Ultra-wideband Antennas

In recent years,the rapid development of wireless technology has put forward higher requirements for the quality and security of modern communication system communication.Frequency-hopping spread-spectrum mobile communication technology is widely used in military communication because of its randomness and strong anti-interference and antifading ability.However,in order to realize the application of frequency-hopping spread spectrum communication technology,it is necessary to use the whip antenna with broadband and ultra-wideband antenna.Therefore,based on the modern military requirements,this paper designs two VHF/UHF band Ultra-Wideband Antennas,and the main work is as follows:1.Research and design of ultra-wideband whip antenna.Based on the idea of structure equivalence,the method that the stepped tapered structure is equivalent to the biconical structure is studied.In order to solve the problem of the split of the ultra-wideband antenna pattern,the metal sleeve loading technology is studied,so as to improve the radiation characteristics of the antenna by changing the local current distribution of the dipole antenna through the loading technology.In addition,the multi-section tapered coaxial structure is proposed to realize impedance matching technology in a wide frequency range.The prototype test shows that the VSWR is less than 3 in the working bandwidth,the pattern keeps horizontal omni-directional,and the gain in 95% of the bandwidth is greater than 1dBi,except for some frequency points in the low-frequency band.2.Research and design of ultra-wideband array antenna.Based on the research of the above-mentioned ultra-wideband whip antenna,the ultra-wideband binary array antenna is studied to further improve the gain of the low-frequency antenna to meet the needs of vehicle-mounted applications.Through the analysis of the mutual impedance between the array elements,it is proposed to load a tight coupling structure between the two elements to increase the radiation resistance of the antenna at low-frequency points,thereby improving the radiation efficiency of the antenna and increasing the gain of the antenna.In addition,a T-shaped coaxial mismatch equal power divider is used to feed the binary array antenna.The prototype test shows that the antenna VSWR is less than 3 and the gain is greater than 1dBi in the working frequency band(wherein 98% of the working frequency band is greater than2 dBi,and 85% of the working frequency band is greater than 3dBi).