Response correction of a V-band narrow-band filter using tuning metal insertions and Aggressive Space Mapping

This paper describes a procedure to correct manufacturing deviations, usually critical at mm-wave frequencies. A 5-pole narrow-band filter centered at 60 GHz is designed using Groove Gap Waveguide (GGW) cavity resonators coupled by inductive windows. In the presented design, square-shaped tuning metal insertions are included in each cavity, coupling windows, and input-output ports. This strategy allows the design to be tuned by an optimization procedure using Aggressive Space Mapping (ASM) with full-wave simulation as coarse model, and the manufactured piece as the fine model. Since the GGW is a contact-less two-piece waveguide, and the piece with the insertions has a simple manufacturing process and reposition, by few low-cost iterations the desired response can be finally recovered. In the presented case, with one iteration it is obtained a centered response, which exhibits only 1.5 dB of insertion loss and good return loss in the pass band.