A Novel Pinned Cover Design With an Array of Three-Dimensional n-Pole Elements for Low-Frequency Filtering of Microwave Circuit Packages

In the proposed study, a novel miniaturized cover design including three-dimensional (3-D) n-pole (two-, three-, and four-pole) elements, instead of a conventional pinned cover consisting of an array of pins with circular cross section, is suggested to move the bandgap to lower frequencies. The frequency response of the proposed cover design is numerically compared with the conventional pinned cover to show the effect of the number of poles on the filter performance. Furthermore, an experimental study is performed for miniaturized cover with a 5 × 5 array of 3-D three-pole elements to validate the numerical results. Finally, a simple S-shaped 50-Ω microstrip transmission line is built and mounted on the cavity, and the magnitude of the scattering parameters as well as the vertical electric field distributions are compared for the cases with and without an array of 3-D three-pole elements to demonstrate the cavity mode suppression.