Apparatus and method for broadband electromagnetic mode suppression in microwave and millimeterwave packages
AssigneeWemtec, Inc.
InventorWilliam E. McKinzie, III
Life of this patent
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Abstract
A parallel plate waveguide structure may be configured to suppress spurious propagating modes by including a lossy frequency selective surface (FSS) formed from a resistive film. The electromagnetic material properties of individual layers disposed between the conductive plates of the waveguide may be engineered to extend the suppression band of the fundamental TE mode up to the cutoff frequency of the second TE mode, and to simultaneously create a multi-octave TM mode suppression band. Applications include, for example, cavity mode suppression in microwave and millimeterwave assemblies at the board, package, and chip level.
Claims13
A package for an electrical circuit, comprising:
- a first conductive surface;
- a second conductive surface;
- a resistive layer disposed at a first fixed distance from the first conductive surface and a second fixed distance from the second conductive surface;
- a first dielectric material, having a relative dielectric constant greater than unity, disposed between the resistive layer and the first conductive surface;
- and
- a second dielectric material, having a relative dielectric constant greater than or equal to unity, disposed between the resistive layer and the second conductive surface,
- wherein the first distance, the second distance and the relative dielectric constants of dielectric layers disposed between the resistive layer and the conductive surfaces are selected such that propagation of a TE mode is suppressed in amplitude over a selected frequency interval;
- and, the resistive layer has an intrinsic resistance of at least 30 Ohms per square.
A method for controlling parallel-plate waveguide (PPW) modes in a package, the method comprising:
- providing a first and a second conductive surface at least one of the surfaces being a part of the package;
- and
- disposing a lossy frequency selective surface (FSS) between the first conductive surface and the second conductive surface;
- the lossy FSS further comprising;
- a dielectric layer with a resistive film formed thereon or within, and a pattern formed in the resistive film to form an impedance sheet having both a distributed resistance and a distributed capacitance,
- wherein the resistive layer has an intrinsic resistance of at least 30 Ohms per square.
Dependencies are inferred from the claim text.