Method and apparatus for testing microwave devices and circuits in a controlled environment

A method for measuring planar microwave components in a controlled environment without disturbing the controlled environment, comprising:

• mounting the component in a test fixture for use in characterizing planar microwave components in a controlled environment without disturbing the controlled environment during testing, wherein said fixture comprises:
• a mounting block;
• a pair of planar microwave connecting lines each having a first and second end, mounted on said mounting block and wherein the first end of said connecting lines are to be connected electrically to the component;
• a plurality of planar microwave calibration standards mounted on said mounting block;
• and
• a plurality of coaxial connectors mounted on said mounting block wherein said coaxial connectors are electrically connected to the second ends of said pair of connecting lines and to said plurality of calibration standards;
• electrically connecting the terminals of the component to the first ends of said connecting lines;
• placing said test fixture in an environmental control chamber, wherein said environmental control chamber includes a plurality of electrical feed-thrus each with a first coaxial terminal located within said chamber and a second coaxial terminal located outside said chamber;
• electrically connecting a pair of said plurality of first coaxial terminals to said pair of component connectors thereby forming a pair of component test terminals and electrically connecting the remainder of said plurality of coaxial first terminals to said calibration connectors to form a plurality of pairs of calibration terminals;
• establishing the controlled environment;
• calibrating a microwave testing apparatus, the steps of which consists of:
• preloading the microwave testing apparatus with a calibration routine,
• connecting said testing apparatus to each of said pairs of calibration terminals electrically, in sequence,
• measuring the S-parameters of each of the calibration standards,
• calculating calibration coefficients from said scattering (S) parameters using said calibration routine;
• and
• testing the component by electrically connecting said testing apparatus to said pair of component test terminals.

A microwave measurement system for use in characterizing planar microwave components in a controlled environment without disturbing the controlled environment during testing, wherein said system comprises:

• means for measuring microwave characteristics of the microwave components;
• an environmental control chamber containing a plurality of coaxial cables, electrically connected to said means for measuring microwave characteristics;
• a means for electrically connecting said chamber to said means for measuring microwave characteristics;
• means for controlling the environment within said chamber and connected to said chamber;
• and
• a test fixture for use in characterizing planar microwave components in a controlled environment without disturbing the controlled environment during testing, wherein said fixture comprises:
• a mounting block;
• a pair of planar microwave connecting lines each having a first and second end, mounted on said mounting block and wherein the first end of said connecting lines are to be connected electrically to the component;
• a plurality of planar microwave calibration standards mounted on said mounting block;
• and
• a plurality of coaxial connectors mounted on said mounting block wherein said coaxial connectors are electrically connected to the second ends of said pair of connecting lines and to said plurality of calibration standards;
• said test fixture located within said chamber wherein each of said plurality of coaxial connectors is electrically connected to one of said plurality of coaxial cables.

A microwave measurement system for use in characterizing planar microwave components in a controlled environment without disturbing the controlled environment during testing, wherein said system comprises:

• means for measuring microwave characteristics of the microwave components;
• an environmental control chamber containing a plurality of second coaxial cables, comprising:
• a hollow rectangular box;
• a rectangular lid wherein said lid is secured to the top of said box;
• a brass plate, located within said rectangular box which couples said test fixture to said means for establishing the controlled environment;
• a pair of detachable plates fixed securely to the sides of said rectangular box, wherein said pair of plates contain a first plurality of feed-thru ports through which the plurality of second coaxial cables are coupled through;
• a microwave switch, wherein said switch electrically connects each of said plurality of second coaxial cables individually with said means for measuring microwave characteristics for electrically connecting said chamber to said means for measuring microwave characteristics;
• a test fixture for use in characterizing planar microwave components in a controlled environment without disturbing the controlled environment during testing, wherein said fixture comprises:
• a mounting block;
• a pair of planar microwave connecting lines each having a first and second end, mounted on said mounting block and wherein the first end of said connecting lines are to be connected electrically to the component;
• a plurality of planar microwave calibration standards mounted on said mounting block;
• and
• a plurality of coaxial connectors mounted on said mounting block wherein said coaxial connectors are electrically connected to the second ends of said pair of connecting lines and to said plurality of calibration standards;
• said text fixture located within said chamber wherein each of said plurality of coaxial connectors is electrically connected to one of said plurality of second coaxial cables;
• and
• a means for cooling said chamber to cryogenic temperatures, wherein said means for cooling is connected to said chamber and comprises:
• said chamber to cryogenic temperatures further comprises:
• a closed-cycle helium gas refrigerator;
• a cold finger attached to said refrigerator and fixed to said brass plate, located within said rectangular box;
• a compressor, wherein said compressor includes a supply line and a return line which are both connected to said refrigerator;
• a temperature controller;
• a first temperature sensor attached to said cold finger and said temperature controller;
• a second temperature sensor attached to said test fixture and said temperature controller;
• a coil resistor connected to said test fixture and to said temperature controller, wherein said coil resistor is used to supply heat and therefore stabilize the temperature.

A text fixture for use in characterizing planar microwave components in a controlled environment without disturbing the controlled environment during testing, wherein said fixture comprises:

• a brass mounting block comprising:
• a base plate wherein said base plate is symmetric about one axis and comprises:
• a plurality of side edges, wherein said edges are parallel to each other and to said axis,
• a reflect area including two (2) of said plurality of side edges,
• at least one delay area including two (2) of said plurality of side edges, located next to said reflect area,
• a thru area including two (2) of said plurality of side edges, located next to said delay area,
• a plurality of side walls permanently fixed to and extending upward from said plurality of side edges of said base plate which include a plurality of holes wherein the length of said plurality of holes is parallel to said base plate;
• a pair of 50.OMEGA. microstrip connecting lines each having a first and second end, mounted on said reflect area of said mounting block, and wherein the first end of said connecting lines are to be connected electrically to the component, wherein said connecting lines comprise a gold conductor, a gold ground plane and an alumina dielectric;
• a plurality of 50.OMEGA. microstrip TRL calibration standards mounted on said mounting block, wherein said TRL calibration standards comprise a gold conductor, a gold ground plane and an alumina dielectric, wherein said TRL calibration standards further comprise:
• a thru line mounted on said thru area of said mounting block,
• at least one delay line, mounted on said delay area of said mounting block, and
• a pair of reflect lines, mounted on said reflect area of said mounting block;
• a plurality of SMA coaxial connectors mounted within said mounting block wherein said coaxial connectors are electrically connected to the second ends of said pair of connecting lines and to said plurality of calibration standards using wire bonds, and
• a plurality of screws inserted through and extending beyond said base plate for the purpose of securing said test fixture to the controlled environment.