The low conductivity and thin layers of the inlget-printed metal conductors have always been a big concern in paper-based printed electronics for high frequency applications. To provide the fundamental knowledge, the high frequency characteristics of inlget-printed coplanar waveguides on paper substrate were studied experimentally in terms of characteristic impedance and conductor losses using the time domain reflectometry technique. The influences of different printing settings and of geometric parameters on the waveguide's properties were investigated. Considering the measurement accuracy in high frequency characterization, one sample with an impedance of 51.2 Ω was achieved. The electrical stability of the samples was also studied and explained. In addition, one waveguide sample was printed in a way that the pattern area with the highest current density is thickened. This variable ink-layer thiclozess approach has successfiilly been proven as a promising solution to reduce the conductor losses and yet consuming less ink.