Additive Manufacturing of E-Plane Cut Extracted Pole Waveguide Filters With Frequency-Dependent Coupling Apertures

This paper presents additive manufactured extracted pole waveguide filters. The filters are realized with an E-plane cut, which allows the manufacturing with low cost fused deposition modeling (FDM) techniques. Classical extracted pole waveguide filters consist of at least one non-resonating node which couples the extracted pole cavity usually in the H-plane. However, this cutting plane introduces high losses especially if low cost manufacturing techniques are used for the fabrication. The design proposed here stacks the extracted pole cavity above (or even below) the non-resonating node. Advantageously, an extra transmission zero (TZ) apart from the one generated by each extracted pole section can be observed. Additive manufacturing techniques furthermore allow the realization of complex structures. The filters proposed here utilize up to two frequency-dependent coupling apertures, while each frequency-dependent coupling introduces one further TZ nearby the passband.