Abstract
We proposed a broadband bandpass filter for the 60-GHz wireless communication in this work. The device was composed by one short and one open resonator, which was likely to provide composite right/left-handed propagation in the passband. The procedure of designing the device included analyzing the resonance modes of the resonators, estimating the dimensions of the resonators according to the theoretic resonance modes and determining the complete structure parameters through electromagnetic wave simulations. From analyzing the simulation results, the structure was then modified into a short resonator and an I-shaped resonator to improve the performance, and the same design procedure was performed again for this structure. In the result of simulation, we obtained a passband centered at 60.5 GHz with 10.9% fractional bandwidth, and the composite right/left-handed propagation in the passband was verified at the same time. Three fabrication processes capable of grounding the short resonator in the bandpass filter were investigated to realize the device. They were the SU-8 microfabrication, the low temperature co-fired ceramics (LTCC) technology and the UV-lithography on the alumina board. Among the three processes, groundings of the short resonators were achieved by vias for the former two processes and by side-sputtered electrodes for the latter process. Simulation of the device structure for each process was done to optimize the performance. Finally, the device was fabricated by the UV-lithography on alumina board and measured. The measurement result showed a 60 GHz passband similar to the simulation result.