A design of stripline-coaxial vertical transition with ultra-broadband

A vertical transition of stripline-coaxial is presented in this paper. The discontinuousness between the stripline and coax is decreased by increasing the diameter of the coaxial inner conductor and changing the width of the stripline at the connecting location. The simulation results indicate the vswr and insertion loss are below 1.1 and 0.1dB from 1 GHz to 18 GHz, respectively. A prototype 4 ways power divider is also developed with the proposed vertical transition, whose measured vswr is below 1.3 with 40% bandwidth. And the measured insertion loss is less than 0.5 dB. The whole performance is equivalent to the horizontal transition, even better in a certain band. The rationality and practicability of this design are confirmed.