A broad-band LTCC integrated transition of laminated waveguide to air-filled waveguide for millimeter-wave applications

In this paper, a compact and broad-band integrated transition between laminated waveguide in a multilayer low-temperature co-fired ceramic (LTCC) substrate and standard air-filled rectangular waveguide is presented. A parallel inter-coupled two-pole filter equivalent circuit is employed to interpret the working mechanism of the transition and to predict the performance. A Ka-band prototype of the proposed broad-band transition is designed and fabricated in an LTCC substrate. The simulated and measured results of the prototyped transition show good agreement. It has been demonstrated, through the experimental results of the Ka-band prototype that the proposed transition configuration gives an effective bandwidth of over 8% with -15-dB return loss and average -0.4-dB insertion loss over the bandwidth at the Ka frequency band.