The contact properties between metal and monolayer chemical vapor deposition (CVD) graphene were investigated, and coplanar waveguides (CPWs) composed of CVD graphene-based signal lines and Au-based ground lines were fabricated. The reflection coefficients of the CPWs were experimentally measured from 1 to 15 GHz. The contact properties were represented using the equivalent circuit model, which consists of paralell contact resistance R_c and paralell contact capacitance C_c. The calculated reflection coefficients of the model nearly agreed with the measured ones, which indicated that this model is suitable for analyzing the contact properties between metal and graphene up to 15 GHz. Bacause the impedance of C_c (|1/(ωC_c )| = 4.8×10^-3 Ω) is four orders of magnitude lower than that of R_c (50 Ω) at 15 GHz, the current flow is more capacitive and efficient than that in the DC band. The ratio of power consumption and power storage in the microwave band to the total power consumption in the DC band decreased with increasing frequency and incresing C_c. Therefore, higher C_c is preferable in designing microwave devices with a metal/graphene-based feeding structure, such as antennas and transmission lines.