Frequency selective limiting device

A frequency selective limiting unit operable to attenuate microwave signals above a preselected power level comprising:

• a signal-carrying conductor for passing a microwave signal therethrough, said conductor having a pair of end portions and a body portion intermediate said end portions;
• a ferrite covering positioned in surrounding relation with at least said signal-carrying conductor body portion;
• said ferrite covering being formed from generally parallel first and second ferrite members, each said member having a generally rectangular configuration with said first member having a length less than the length of said second member;
• said signal-carrying conductor being positioned between and secured to said first and second ferrite members, said conductor having a preselected length greater than said length of said first ferrite member and substantially equal to said length of said second ferrite member to expose said conductor end portions upon positioning said conductor between said first and second ferrite members;
• said signal-carrying conductor being supported over its entire length by said second ferrite member;
• RF shielding means surrounding said first and second ferrite members;
• said signal-carrying conductor and said first and second ferrite members adapted to be positioned in preselected spatial relation with DC magnet means, said DC magnet means providing said first and second ferrite members with an external DC biasing magnetic field;
• and
• said DC magnet means in association with said ferrite covering being operable to attenuate by a predetermined level a microwave signal above a preselected threshold power level passed through said signal-carrying conductor.

A method for assembling a frequency selective limiting unit operable in association with external DC biasing means to attenuate microwave signals above a preselected power level comprising the steps of:

• securing a generally planar second ferrite member to a metallized surface of a substrate layer;
• disposing a generally linear signal-carrying conductor having a pair of opposing end portions and a center body portion on said second ferrite member, said signal-carrying conductor having a length substantially equal to the length of said second ferrite member;
• disposing a generally planar first ferrite member having a length less than the lengths of said signal-carrying conductor and said second ferrite member on said signal-carrying conductor body portion;
• positioning said first ferrite member on said signal-carrying conductor so that said conductor opposing end portions are exposed;
• and
• surrounding the outer surfaces of said first and said second ferrite members with a metallic material to enclose said first and said second ferrite members in an RF shield.