In this paper, structure and microwave properties of a substrate removed GaAs/AlGaAs traveling wave electro-optic modulator structure were analyzed and simulated by using the finite element numerical technique for lower loss, simultaneous matching of optical and microwave velocities and impedance matching with 50 Ω. The effects of core layer thickness, claddings thicknesses, and width of the modulator on the microwave effective index nm were investigated, the characteristic impedance ZC, the microwave losses α, and the half-wave voltagelength product VπL were calculated. The results of the simulation suggest that the electrical bandwidth of 22 GHz and the optical bandwidth of 48 GHz can be obtained for fully matched, lower loss structure, which correspond to a 13 V$cm drive voltage.