Design Of Wide-band Coupling Leaky Coaxial Cables

Leaky coaxial cable is a kind of coaxial cables of which the outer conductor isincomplete closed. It has two functions of both transmission line and continuousantenna. It is widely used in confined areas such as mines, subways, tunnels, caves,high-speed railway, underground markets, military bunkers, and other buildings in blindor semi-blind zones for wireless communications because of its particularity andsignificant effects. The research on leaky coaxial cable is of profound significance.First of this paper, the structure, classification and the theory, mode, direction ofradiation of leaky coaxial cables is briefly introduced. And then, it describes mainelectrical characteristics of leaky coaxial cables including characteristic impedance,operation frequency band, coupling loss and attenuation constant, which are illustratedwith examples through software simulation. Finally，a kind of wide-band coupling leakycoaxial cable is designed according to the relevant theory and standards.The cable designed in this paper is foamed polyethylene dielectric corrugatedcopper tube outer conductor leaky coaxial cable, which belongs to coupling leakycoaxial cables. The characteristic impedance, coupling loss and attenuation constant ofthe leaky coaxial cable in this paper satisfy the relevant standards in particularfrequencies by electromagnetic simulation analyzing and sample testing, and themeasurement results are in agreement with the simulation results. The relevant theoryand design method of leaky coaxial cable described in this paper could be used todevelop other types of leaky coaxial cables, and they have good universality.