This paper presents millimeter wave characterization and models of various wire bond transitions between chip’s ground-signal-ground pad (GSG) and microstrip (MS), include single-wire-nomatch MS-GSG transition, double-wire-nomatch MS-GSG, single-wire-match MS-GSG transition, and double-wire-match MS-GSG transition. It also presents the 3D full-wave electromagnetic simulation. Analysis results show that the double-wire-match MS-GSG transition’s characteristic is better than other three transitions in the whole W band. The accurate extracted parameter values are used for the lumped equivalent circuit model, whose simulation results are good with the full wave simulation results. The error between lumped equivalent circuit and full-wave models is of the order of ±0.2dB for S11 and S21 in the frequency range 75 - 105GHz. The proposed lumped equivalent circuit is suitable to be implemented in commercial microwave CAD tools for the electromagnetic sensor designing.