Optimized Design of Low Loss Differential Mode Bilateral Coplanar Waveguide

The optimized design of a low loss differential mode bilateral coplanar waveguide (DBCPW) is presented. It is based on the printed circuit board (PCB) technology without using the vias. The conductor loss is reduced by decreasing the current crowing on the signal lines. The simulation results show that after the optimization the magnitude of S21 of the proposed DBCPW reaches to -0.190 dB at 37.5GHz with a length of 40 mm. It is the best one compared with that of optimized microstrip line, coplanar waveguide (CPW) and differential coplanar waveguide (DCPW), which is -0.473 dB, -0.249 dB and -0.219 dB, respectively. It was found that the optimized results from the lowest loss may also give the reasonable value of the characteristic impedance. The propagation phase constant of DBCPW is also given, which presents its low dispersion characteristic. The proposed DBCPW is useful both in circuits and in antennas, especially for millimeter wave antenna arrays with electrically large size where the requirement on the loss of the transmission line is quite critical.