# US 11,442,086 B2 · Microwave radiation detector

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- Number: US 11,442,086 B2
- Document ID: US11442086B2
- Status: Granted
- Kind: B2
- Application number: 16/766,152
- Filed: 2018-11-22
- Published: 2020-09-10
- Granted: 2022-09-13
- Earliest claimed: 2017-11-23
- Assignees: IQM Finland Oy
- Applicants: IQM Finland Oy
- Inventors: Mikko Mottonen; Roope Kokkoniemi; Visa Vesterinen; Russell Lake
- Web page: https://patentgrep.com/patent/US11442086B2

## CPC

- G01R 21/02: by thermal methods {, e.g. calorimetric}
- G01K 7/006: {using superconductive elements}
- G01K 11/006: {using measurement of the effect of a material on microwaves or longer electromagnetic waves, e.g. measuring temperature via microwaves emitted by the object (G01K17/003, G01J5/00 take precedence; measuring the effect of a material on X-, gamma- or particle radiation G01K11/30)}
- H10N 60/12: Josephson-effect devices
- G01J 2005/208: {superconductive}
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)
- G01K: MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR (radiation pyrometry G01J5/00)
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- G01J: MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY (light sources F21, H01J, H01K, H05B; investigating properties of materials by optical means G01N)

## Abstract

A detector of microwave radiation includes a signal input and a detector output. An absorber element of ohmic conductivity is coupled to said signal input through a first length of superconductor. A variable impedance element, the impedance of which is configured to change as a function of temperature, is coupled to the detector output through a second length of superconductor. The detector also includes a heating input and a heating element coupled to the heating input through a third length of superconductor. The absorber element, the variable impedance element, and the heating element are coupled to each other through superconductor sections of lengths shorter than any of said first, second, and third lengths of superconductor.

## Claims

### Claim 1

A detector of microwave radiation, comprising:
a signal input and a detector output;
an absorber element of ohmic conductivity, coupled to said signal input through a first length of superconductor; and
a variable impedance element, the impedance of which is configured to change as a function of temperature, coupled to said detector output through a second length of superconductor,
wherein:
the detector comprises a heating input,
the detector comprises a heating element coupled to said heating input through a third length of superconductor, and
said absorber element, said variable impedance element, and said heating element are coupled to each other through superconductor sections of lengths shorter than any of said first, second, and third lengths of superconductor to allow hot electron diffusion between said absorber element, said variable impedance element, and said heating element while blocking quasiparticle thermal transport of heat through said first, second, and third lengths of superconductor.

### Claim 2 (depends on 1)

The detector according to claim 1, further comprising microwave filters along at least one of said first and third lengths of superconductor.

### Claim 3 (depends on 1)

The detector according to claim 1, further comprising a low-pass or band-pass microwave filter along said third length of superconductor.

### Claim 4 (depends on 1)

The detector according to claim 1, further comprising a band-pass microwave filter along said first length of superconductor.

### Claim 5 (depends on 4)

The detector according to claim 4, wherein said band-pass microwave filter is controllable with regard to at least one of: middle frequency of its pass band, or width of its pass band.

### Claim 6 (depends on 1)

The detector according to claim 1, wherein:
said heating input is a first heating input coupled to a first end of said heating element, and comprises a first heating current lead and a first voltage measurement connection; and
said detector comprises a second heating input that is coupled to a second end of said heating element, and comprises a second heating current lead and a second voltage measurement connection.

### Claim 7 (depends on 1)

The detector according to claim 1, wherein:
said absorber element and said variable impedance element have a common longitudinal axis; and
said heating element runs parallel to at least one of said absorber element and said variable impedance element with a perpendicular displacement therefrom.

### Claim 8 (depends on 1)

The detector according to claim 1, wherein:
said variable impedance element has a longitudinal axis; and
said absorber element and said heating element form a pattern that is symmetrical with respect to the longitudinal axis of said variable impedance element.

### Claim 9

A detector arrangement for detecting microwave radiation, comprising:
at least one detector; and
a resonance measurement circuit configured to measure the resonance frequency of a tank circuit coupled to said detector output,
wherein:
the detector is a detector of microwave radiation,
the detector comprises a signal input, a detector output, an absorber element of ohmic conductivity coupled to said signal input through a first length of superconductor, and a variable impedance element the impedance of which is configured to change as a function of temperature,
the variable impedance element is coupled to said detector output through a second length of superconductor,
the detector comprises a heating input,
the detector comprises a heating element coupled to said heating input through a third length of superconductor, and
said absorber element, said variable impedance element, and said heating element are coupled to each other through superconductor sections of lengths shorter than any of said first, second, and third lengths of superconductor to allow hot electron diffusion between said absorber element, said variable impedance element, and said heating element while blocking quasiparticle thermal transport of heat through said first, second, and third lengths of superconductor.

### Claim 10 (depends on 9)

The detector arrangement according to claim 9, further comprising:
a heating current controller configured to make a heating current of known magnitude flow through said heating input.

### Claim 11 (depends on 10)

The detector arrangement according to claim 10, wherein:
said heating input is a first heating input coupled to a first end of said heating element in said detector, and comprises a first heating current lead and a first voltage measurement connection;
said detector comprises a second heating input that is coupled to a second end of said heating element in said detector, and comprises a second heating current lead and a second voltage measurement connection;
said heating current controller comprises a series coupling of a voltage source and a ballast resistor, coupled across said first and second heating current leads; and
said detector arrangement comprises a voltmeter coupled across said first and second voltage measurement connections.

### Claim 12 (depends on 11)

The detector arrangement according to claim 11, wherein:
the detector arrangement is configured to calibrate the detector by making said series coupling feed a calibrating current through said heating element and measuring corresponding change in the resonance frequency of the tank circuit; and
the detector arrangement is configured to measure changes in the resonance frequency of the tank circuit during detection of microwave radiation and to produce a measurement signal indicative of such changes.

### Claim 13 (depends on 11)

The detector arrangement according to claim 11, wherein:
the detector arrangement is configured to make said series coupling feed a compensating current through said heating element in dependence with a feedback coupling to keep the resonance frequency of the tank circuit constant during detection of microwave radiation; and
the detector arrangement is configured to produce a measurement signal indicative of the magnitude of said compensating current.