Filter with spurious characteristic controlled

A filter comprising:

• a substrate;
• connection means for providing electrical connection;
• a filter circuit on a top surface of said substrate including at least a resonator electromagnetically resonating at a resonance frequency at a microwave band and a millimeter wave band, for filtering an input signal from said connection means through said resonator and outputting the filtered signal through said connection means;
• a metal box including a top plate confronting said top surface and said filter circuit, side walls, and a bottom plate, for containing and supporting said substrate and filter circuit, a portion of said side walls supporting said connection means, wherein a first portion of said input signal is transferred through said filter circuit and a second portion of said input signal is transferred through a portion of said metal box in the wave-guided mode, said second portion providing a spurious characteristic of said filter, an inside surface of said top plate having a shape other than a plane to control the spurious characteristic, wherein said top plate has a thickness between a top surface thereof and said inside surface and said thickness decreases stepwise and then, increases stepwise in a direction.

A filter comprising:

• a substrate;
• connection means for providing electrical connection;
• a filter circuit on a top surface of said substrate including at least a resonator electromagnetically resonating at a resonance frequency at a microwave band and a millimeter wave band, for filtering an input signal from said connection means through said resonator and outputting the filtered signal through said connection means;
• a metal box for containing and supporting said substrate and filter circuit, said metal box including:
• a top plate confronting said top surface of said substrate and said filter circuit, side walls, and a bottom plate;
• wherein a first portion of said input signal is transferred through said filter circuit, a second portion of said input signal is transferred through said top plate of said metal box in the wave-guided mode, said second portion provides a spurious characteristic of said filter, and an inside surface of said top plate has a protruding portion in which a thickness of said top plate successively increases and then, successively decreases in a direction to shift a spurious resonance frequency in said spurious characteristic.

A filter comprising:

• a substrate;
• connection means for providing electrical connection;
• a filter circuit on a top surface of said substrate including at least a resonator electromagnetically resonating at a resonance frequency at a microwave band and a millimetric wave band, for filtering an input signal from said connection means through said resonator and outputting the filtered signal through said connection means;
• a metal box including a top plate confronting said top surface and said filter circuit, side walls, and a bottom plate, for containing and supporting said substrate and filter circuit, a portion of said side walls supporting said connection means, wherein a first portion of said input signal is transferred through said filter circuit and a second portion of said input signal is transferred through a portion of said metal box in a guided mode, said second portion providing a spurious characteristic of said filter, said side wall having a protruding portion to control the spurious characteristic, wherein said protruding portion is arranged at a comer of successive two of said side walls and combined with said successive two of said side walls.

A filter comprising:

• a substrate;
• connection means for providing electrical connection;
• a filter circuit on a top surface of said substrate including at least a resonator electromagnetically resonating at a resonance frequency at a microwave band and a millimeter wave band, for filtering an input signal from said connection means through said resonator and outputting the filtered signal through said connection means;
• a metal box including a top plate confronting said top surface and said filter circuit, side walls, and a bottom plate, for containing and supporting said substrate and filter circuit, a portion of said side walls supporting said connection means, wherein a first portion of said input signal is transferred through said filter circuit and a second portion of said input signal is transferred through a portion of said metal box in the wave-guided mode, said second portion providing a spurious characteristic of said filter,
• further comprising a dielectric plate on an inner surface of said metal box on the side of said top surface of said substrate,
• wherein said second portion of said input signal is transferred through said portion of said metal box and said dielectric plate in a guided mode, said dielectric plate shifting said spurious characteristic of said filter.