Research On Wideband Leaky Coaxial Cables And Leaky Wave Antennas For 5G Applications

Leaky coaxial cable and leaky wave antenna based on periodic leaky wave structure because of that have wideband radiation characteristics and are widely used in wireless communication and detection systems.With the development of the Fifth Generation Mobile Communication（5G）Technology,the width and number of communication frequency band are increasing rapidly,and the demand for the coverage of communication and detection beam are increasing.Therefore,new challenges are posed to the single spatial harmonic radiation bandwidth and beam scanning angle characteristics of leaky coaxial cable and leaky wave antenna.To solve this problem,this paper studies the bandwidth broadening method of single spatial harmonic radiation of periodic leaky wave structure based on TEM mode transmission line,and proposes a wideband leaky coaxial cable structure with high-order spatial harmonic radiation suppression and a wideband wide-angle scanning leaky wave antenna structure.The research results can provide theoretical and technical support for the design of wideband leaky wave radiation structure in 5G communication and detection applications.The main work and innovations are summarized as follows:1.A high-order spatial harmonic radiation suppression method based on the periodic leaky wave structure of TEM mode transmission line is proposed.Based on this method,a wideband leaky coaxial cable structure with–2^ndto–4^thspatial harmonic radiation suppression characteristics is designed to realize wideband matching and stable radiation without strong reflection points in the frequency band of 0.9GHz-3.7 GHz.On this basis,the standing wave characteristic optimization method of high-order space harmonic radiation suppression leaky cable based on periodic structure small reflection theory is further proposed,which effectively reduces the standing wave ratio of leaky cable in the working frequency band.2.Aiming at the problem that the number of slots in the cycle increases and the processing difficulty of densely distributed slots increases with the increase of high-order spatial harmonic suppression times of leaky cable,a high-order spatial harmonic radiation suppression wideband leaky cable structure with circumferential combined slot arrangement is proposed,which not only realizes the higher-order spatial harmonic radiation suppression,but also reduces the slot distribution density in the cycle.Based on this structure,the wideband leakage cable with–2^ndto-5^thspatial harmonic radiation suppression is designed,processed and tested,the stable working characteristics of the leakage cable in the frequency band of 0.7 GHz-3.7 GHz are realized,and the effectiveness of the proposed design method is verified.3.Based on the substrate integrated coaxial transmission structure,a wideband wide-angle scanning leaky wave antenna with-2^ndto-4^thspatial harmonic radiation suppression is designed.The antenna realizes the wide-angle scanning characteristics of-1^stspatial harmonic from-73°to 60°in the frequency band of 14 GHz-40 GHz,which effectively improves the beam scanning angle range of single spatial harmonic of the antenna.The variation range of radiation gain of the antenna is 5 to 14.6 d Bi,and the radiation efficiency is more than 45%.The wideband leaky wave antenna is processed,and the test results are in good agreement with the simulation results,which verifies the working performance of the antenna.