E-plane techniques tune filters to 170 GHz

CAD algorithms have been developed to improve E-plane filter designs for the three viable configurations of direct coupled cavity filters in mm-wave applications. A passband ripple, upper and lower band edge frequencies, the number of sections and/or out-of-band rejection needed specify the filter once the device dimensions are set. The width of the inductive strips and spacings are then calculated. An analysis program applies a scattering matrix to project the frequency response of the filter for comparison with the design goals. The inductive strips of the filters are supported by a split-block housing which is manufactured by a numerically-controlled machine. The strips themselves are formed photolithographically and chemically etched to achieve accuracies exceeding 0.013 mm. Features of a Chebyshev filter produced using the techniques are described.