A Compact and Low-Radiation CPW Probe Pad Using CBCPW-to-Microstrip Transitions for V-Band LTCC Applications

In this paper, a compact and low-radiation coplanar waveguide lines (CPW) probe pad using vialess conductor-backed coplanar waveguide (CBCPW)-to-microstrip transitions is presented for V-band low-temperature cofired ceramic (LTCC) applications. To reduce the radiation loss due to open-end and transition discontinuities, a vialess CBCPW structure with a edge cut back is proposed. The back pad and an optimum transition length suppress the radiation loss of the standard CPW probe pad by 30% and 10%, respectively, compared to a conventional vialess transition. In particular, at 66 GHz, radiation is completely suppressed for the proposed transition and its insertion loss is 0.15 dB at that frequency.