CPC H01P 1/207 (2013.01) [H01P 3/121 (2013.01); H01P 3/123 (2013.01)] | 20 Claims |
1. A multi-layer signal filter comprising at least three physical layers, wherein each layer has through going apertures arranged with an offset to the apertures of at least one adjoining layer, each layer further has a filter channel opening for receiving signals to be filtered, wherein the apertures are arranged along a perimeter outside the filter channel opening, and wherein the apertures are arranged with a central surface portion increasing the edge length of the aperture.
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