Integrated capacitance structures in microwave finline devices

An apparatus for detecting microwave energy in a waveguide, said apparatus including a dielectric substrate disposed within said waveguide and extending between opposing first and second interior walls of said waveguide, said dielectric substrate having thereon metallization on a first substantially planar surface, said metallization defining at least a detection region upon said first surface, said metallization defining a gap of exposed dielectric surface between opposing margins of metallization, said metallization further forming an input transition region of said dielectric surface, the improvement wherein:

• said dielectric substrate forms a taper at a leading edge thereof from maximum waveguide dimension of said substrate to minimum waveguide dimension of said substrate thereby to define a transition from a free-space waveguide to a dielectrically-loaded waveguide, said taper defining an angle of no greater than thirty degrees with said first and second interior walls;
• said metallization including at least a first metallization layer;
• and
• a termination region on said dielectric surface, said termination region being defined by said first metallization layer, said first metallization layer having formed therein a slot of exposed dielectric surface of a length up to about one quarter-wavelength in axial length of said waveguide, said slot defined by a first margin and a second margin opposing said first margin, said slot extending from said detection region to a termination boundary, said first metallization layer being d.c.-isolated from ground potential on said dielectric substrate in order to permit extraction of a detected signal as a d.c. signal from said first metallization layer.

An apparatus for detecting microwave energy in a waveguide, said apparatus including a dielectric substrate disposed within said waveguide and extending between opposing first and second interior walls of said waveguide, said dielectric substrate having thereon metallization on a first substantially planar surface, said metallization defining at least a detection region upon said first surface, said metallization defining a gap of exposed dielectric surface between opposing margins of metallization, said metallization further forming an input transition region of said dielectric surface, the improvement wherein:

• said metallization includes at least a first metallization layer, said apparatus further including a termination region on said dielectric surface, said termination region being defined by said first metallization layer, said first metallization layer having formed therein a slot of exposed dielectric surface of a length up to about one quarter-wavelength in axial length of said waveguide, said slot defined by a first margin and a second margin opposing said first margin, said slot extending from said detection region to a termination boundary, said first metallization layer being d.c.-isolated from ground potential on said dielectric substrate in order to permit extraction of a detected signal as a d.c. signal from said first metallization layer;
• said metallization further including a second metallization layer and a third metallization layer, said second metallization layer being d.c.-coupled to said first interior wall and said third metallization layer being d.c.-coupled to said second interior wall, said first and second metallization layers defining said detecting region at the position of closest convergence of opposing third and fourth margins of said second and third metallization layers on said dielectric surface, said detecting region having mounted thereto a diode, said diode being coupled between said third margin and said second margin across said detecting region, and thereby between said second metallization layer and said third metallization layer.

An apparatus for detecting microwave energy in a waveguide, said apparatus including a dielectric substrate disposed within said waveguide and extending between opposing first and second interior walls of said waveguide, said dielectric substrate having thereon metallization on a first substantially planar surface, said metallization defining at least a detection region upon said first surface, said metallization defining a gap of exposed dielectric surface between opposing margins of metallization, said metallization further forming an input transition region of said dielectric surface, the improvement wherein:

• said metallization includes at least a first metallization layer, and a second metallization layer, said first metallization layer being d.c. isolated from ground, said first metallization layer being separated from said second metallization layer by at least a first slit of dielectric material, and wherein said apparatus further includes at least a first distributed capacitance means comprising at least one metallization layer and at least one thin-film dielectric stratum, said distributed capacitance means being disposed along said first slit and bridging between said first metallization layer and said second metallization layer, wherein capacitance of said distributed capacitance means is sufficient to provide a.c. coupling between said first metallization layer and said second metallization layer.