E-Band Plate-Laminated Waveguide Filters and Their Integration Into a Corporate-Feed Slot Array Antenna With Diffusion Bonding Technology

This paper demonstrates plate-laminated waveguide filters in diffusion bonding technology for the first time and shows their uses in the integration with a corporate-feed slot array antenna for E-band ultrahigh capacity point-to-point communications. First, a single-cavity resonator model is studied and the measured high unloaded quality of 2121 at 79.07 GHz indicates its potential in the design of low-loss filters. Consequently, a sixth-order T-shaped cavity bandpass filter that comprises of ten cavity resonators is developed. It exhibits insertion losses of 3.4 and 3.3 dB at 78.5 GHz at two output ports, a 3-dB fractional bandwidth of 20.5%, as well as a small in-band amplitude/phase difference. Then, a fourth-order bandstop filter based on a band-rejection element is presented. It provides a high rejection level of 55 dB at 78.5 GHz and insertion losses of 0.44 and 0.28 dB at 73.5 and 83.5 GHz. The architectures of the proposed filters show attractive compatibility properties for integration. Finally, the proposed filters are fully integrated into a corporate-feed circuit of a 16 × 16-element slot array antenna without an interconnection circuit. With the seamless integration, the proposed building blocks demonstrate well-preserved high efficiency (only a low loss is introduced by the filters) and unchanged radiation characteristic (low sidelobe level, low cross polarization, and high directivity) in the designed passband, as well as specified bandstop performance.