Design of 4–5GHz transition from double-ridge waveguide to coaxial line

This paper presents a transition from double-ridge waveguide to coaxial line, working at 4-5 GHz. The size of the double-ridge waveguide is WRD350. The design of the transition is based on the theory of mode conversion and step-impedance matching. The transition between the high and low impedance is achieved by employing the Chebyshev type of quarter-wavelength step-impedance matching. Using lead-inserted transition for leading the coaxial probe insert the waveguide, as we know, the dominant mode of the ridge waveguide is different from the coaxial line. If the inner conductor of the connector contacts the down-ridge directly, the VSWR of two ports is very bad. However, when the probe has a cylinder bottom and increasing impedance matching transitions, a good performance can be got. Using simulation software HFSS, the simulation results show that the VSWR in the frequency range 4-5 GHz is less than 1.1. The test results show that the adapter has a good performance.