A Compact W-band Diplexer for Integration with an Electronically Steerable Focal Plane Array Antenna System

A waveguide folded diplexer is presented that is designed to provide frequency division duplex operation of electronically steerable focal-plane-array (FPA) antennas for W-band wireless backhaul links. This design overcomes manufacturing challenges associated with small dimensions at these high frequencies (reaching the required tolerance of $\pm 15 \mu \mathrm{m}$) and the difficulties of integration with the closely-spaced FPA elements. Bandpass filters for the 94-97 GHz and 106-109GHz bands are synthesized utilizing waveguide cavity TE
102
resonators with inductive iris coupling through a combined analytical-numerical optimization approach. The final assembly has a three-fold compact 10th-order configuration and the prototype is manufactured using CNC milling. The measured reflection coefficients are ≤ −15dB, the isolation level is ≥ 55dB, and the insertion loss is ~ 1dB.