### Abstract

*Q*antenna is placed close to a conductive material, e.g., a hot metal plate, the effective noise temperature of the antenna becomes proportional to the temperature of the material. Contrary to the conventional noise thermometer in which a resistor is embedded in the material, the method requires neither galvanic nor thermal contact. If the antenna impedance at different frequencies is known, the temperature of the object can be calculated from the total voltage noise of the antenna. We show, however, that for high‐

*Q*antennae the knowledge of the impedance at resonance is adequate to determine the unknown temperature. Consequently, the temperature of moving objects can be measured via synchronous monitoring of the total noise of the antenna and its impedance at resonance. Since only electrically conductive objects create magnetic field noise, the method is immune to nonconductive contamination of the surface.

Original language | English |
---|---|

Pages (from-to) | 771 - 776 |

Number of pages | 6 |

Journal | Journal of Applied Physics |

Volume | 74 |

Issue number | 2 |

DOIs | |

Publication status | Published - 1993 |

MoE publication type | A1 Journal article-refereed |

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### Cite this

*Journal of Applied Physics*,

*74*(2), 771 - 776. https://doi.org/10.1063/1.354865

}

*Journal of Applied Physics*, vol. 74, no. 2, pp. 771 - 776. https://doi.org/10.1063/1.354865

**Inductive noise thermometer : Theoretical aspects.** / Seppä, Heikki; Varpula, Timo.

Research output: Contribution to journal › Article › Scientific › peer-review

TY - JOUR

T1 - Inductive noise thermometer

T2 - Theoretical aspects

AU - Seppä, Heikki

AU - Varpula, Timo

N1 - Project code: SÄH 1204

PY - 1993

Y1 - 1993

N2 - We describe a new noncontacting method for measuring the temperature of electrically conducting objects by sensing the magnetic field noise. When a high‐Q antenna is placed close to a conductive material, e.g., a hot metal plate, the effective noise temperature of the antenna becomes proportional to the temperature of the material. Contrary to the conventional noise thermometer in which a resistor is embedded in the material, the method requires neither galvanic nor thermal contact. If the antenna impedance at different frequencies is known, the temperature of the object can be calculated from the total voltage noise of the antenna. We show, however, that for high‐Q antennae the knowledge of the impedance at resonance is adequate to determine the unknown temperature. Consequently, the temperature of moving objects can be measured via synchronous monitoring of the total noise of the antenna and its impedance at resonance. Since only electrically conductive objects create magnetic field noise, the method is immune to nonconductive contamination of the surface.

AB - We describe a new noncontacting method for measuring the temperature of electrically conducting objects by sensing the magnetic field noise. When a high‐Q antenna is placed close to a conductive material, e.g., a hot metal plate, the effective noise temperature of the antenna becomes proportional to the temperature of the material. Contrary to the conventional noise thermometer in which a resistor is embedded in the material, the method requires neither galvanic nor thermal contact. If the antenna impedance at different frequencies is known, the temperature of the object can be calculated from the total voltage noise of the antenna. We show, however, that for high‐Q antennae the knowledge of the impedance at resonance is adequate to determine the unknown temperature. Consequently, the temperature of moving objects can be measured via synchronous monitoring of the total noise of the antenna and its impedance at resonance. Since only electrically conductive objects create magnetic field noise, the method is immune to nonconductive contamination of the surface.

U2 - 10.1063/1.354865

DO - 10.1063/1.354865

M3 - Article

VL - 74

SP - 771

EP - 776

JO - Journal of Applied Physics

JF - Journal of Applied Physics

SN - 0021-8979

IS - 2

ER -