GB2325053A - Measurement of microwave radiation - Google Patents

Measurement of microwave radiation Download PDF

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Publication number
GB2325053A
GB2325053A GB9709299A GB9709299A GB2325053A GB 2325053 A GB2325053 A GB 2325053A GB 9709299 A GB9709299 A GB 9709299A GB 9709299 A GB9709299 A GB 9709299A GB 2325053 A GB2325053 A GB 2325053A
Authority
GB
United Kingdom
Prior art keywords
microwave
microwave radiation
measurement
frequency selective
level
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB9709299A
Other versions
GB9709299D0 (en
Inventor
Christopher Budd
Stewart Robert Chesterfield
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Matra Bae Dynamics UK Ltd
Original Assignee
Matra Bae Dynamics UK Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Matra Bae Dynamics UK Ltd filed Critical Matra Bae Dynamics UK Ltd
Priority to GB9709299A priority Critical patent/GB2325053A/en
Publication of GB9709299D0 publication Critical patent/GB9709299D0/en
Priority to CA002288860A priority patent/CA2288860A1/en
Priority to JP10548902A priority patent/JP2000513106A/en
Priority to PCT/GB1998/001333 priority patent/WO1998052058A1/en
Priority to EP98920659A priority patent/EP0980530A1/en
Publication of GB2325053A publication Critical patent/GB2325053A/en
Priority to NO995463A priority patent/NO995463L/en
Withdrawn legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R21/00—Arrangements for measuring electric power or power factor
    • G01R21/02—Arrangements for measuring electric power or power factor by thermal methods, e.g. calorimetric
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/28—Testing of electronic circuits, e.g. by signal tracer
    • G01R31/282—Testing of electronic circuits specially adapted for particular applications not provided for elsewhere
    • G01R31/2822—Testing of electronic circuits specially adapted for particular applications not provided for elsewhere of microwave or radiofrequency circuits

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Investigating Or Analyzing Materials Using Thermal Means (AREA)

Abstract

A microwave radiation pulse measuring device comprises calorimetric means 2 and a frequency selective filter 3. The filter 3 being arranged between the calorimetric means 2 and the source of the microwave radiation 1. The calorimetric means may comprise a reservoir of ethanol which absorbs the filtered microwave energy and expands up a capillary tube 5 such that the level of the ethanol within the capillary indicates the level of microwave energy absorbed. The level of the liquid in the capillary may be measured using a capacitive arrangement. The frequency selective filter may comprise a dielectric layer on which is formed an array of conductive elements. Two such layers may be arranged such that they may be moved relative to one another to adjust the frequency of the filter.

Description

MEASUREMENT OF MICROWAVE RADIATION This invention relates to apparatus for the measurement of the power and spectra of microwave radiation. The invention has particular application to the measurement of brief, intense microwave pulses.
In certain areas of engineering design and research, there is a need to characterise the outputs of devices which generate brief (often sub-microsecond) but very powerful (often gigawatt) bursts of broadband and microwave energy. In such cases, two of the key features to be determined are often total pulse energy and spectrum.
It is widely acknowledged in the microwave measurement community that such measurements are very difficult to perform reliably and accurately, especially in those cases where the source device is destroyed in the microwave-emission process and can therefore emit only one pulse.
One of the difficulties in this measurement task is that all conventional microwave pulse measurement techniques require a triggering signal; basically to determine the moment at which data capture begins. This can be a serious problem with expensive one-shot devices since the triggering process usually itself requires some empirical adjustment.
The present invention has the advantage that it requires no triggering mechanism.
Further, the invention provides a means for measurement of the microwave energy emitted by a pulsed device within a particular band of frequencies. By employing a bank of such instruments, total energy output and spectrum of a microwave pulse can be measured.
The present invention comprises apparatus for the measurement of microwave radiation including calorimetric means, thermally responsive to incident microwave radiation emitted from a remote source, and a frequency selective filter located between said calorimetric means and said source for passing a pre-defined band of microwave frequencies.
The invention thus allows the measurement of total microwave power only in that frequency band which passes through the filter.
It has the advantage that it can be reused indefinitely, providing a continuous scale of absorbed energy. The calorimetric means may be of the type in which the incident microwave energy is absorbed by a liquid (eg ethanol). The liquid then expands along a capillary tube and the expansion of the liquid is used to infer the change in its temperature and (indirectly) the amount of microwave energy absorbed.
Preferably the calorimeter is insulated from other sources of heat and vibration or mechanical shock.
One suitable type of calorimeter is described in Conference Proceedings "BEAMS 96" pp461-464 by A.L. Lisichkin et al.
Preferably the frequency selective filter comprises a dielectric surface on which arrays of conducting elements are printed. Two or more such dielectric surfaces may be stacked to form a composite assembly. The spacing and size of the conducting elements and the spacing of the surfaces dictate the frequency band limiting properties of the filter. US 4307404 describes a similar device for antenna applications.
The filter may optionally incorporate means for moving one surface relative to another thereby modulating its frequency characteristics. This modulation of the frequency characteristic is described in detail in European patent EP-B-468623.
An embodiment of the invention will now be described, by way of example only with reference to the drawings.
Therein, a source 1 of brief, intense microwave pulses irradiates an ethanol filled calorimeter 2 via a band-pass filter 3. The calorimeter 2 comprises a reservoir 4 and capillary 5.
The band-pass filter 3 is a layered frequency selective surface assembly having a plurality of dielectric substrates each with an array of electrically conductive elements disposed thereon. The geometry of the arrays and the spacing between substrates is chosen to match the frequency pass-band of interest.
Those frequencies which are allowed to pass through the filter 3 irradiate the ethanol contained within the calorimeter 2 causing heating and expansion of the liquid.
The expansion of liquid is measured by monitoring its level in the capillary 5. This can be done by bonding two metallic strips 6 to the outer surface of the capillary and measuring the capacitance change.

Claims (7)

1. Apparatus for the measurement of microwave radiation including calorimetric means, thermally responsive to incident microwave radiation emitted from a remote source, and a frequency selective filter located between said calorimetric means and said source for passing a pre-defined band of microwave frequencies.
2. Apparatus according to claim 1 in which the calorimetric means comprises a reservoir of liquid whose expansion in response to irradiation of microwave energy is measured by monitoring its level in a capillary tube.
3. Apparatus according to claim 2 in which the level of liquid in the capillary tube is determined by measuring the capacitance of the capillary tube.
4. Apparatus according to either of claims 2 or 3 in which the liquid is ethanol.
5. Apparatus according to any preceding claim in which the frequency selective filter comprises at least one dielectric substrate on which is printed an array of electrically conducting elements.
6. Apparatus according to claim 5 in which the frequency selective filter comprises at least two such dielectric substrates and means for moving one surface relative to another.
7. Apparatus for the measurement of microwave radiation substantially as hereinbefore described with reference to the drawing.
GB9709299A 1997-05-09 1997-05-09 Measurement of microwave radiation Withdrawn GB2325053A (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
GB9709299A GB2325053A (en) 1997-05-09 1997-05-09 Measurement of microwave radiation
CA002288860A CA2288860A1 (en) 1997-05-09 1998-05-08 Measurement of microwave radiation
JP10548902A JP2000513106A (en) 1997-05-09 1998-05-08 Measuring microwave radiation
PCT/GB1998/001333 WO1998052058A1 (en) 1997-05-09 1998-05-08 Measurement of microwave radiation
EP98920659A EP0980530A1 (en) 1997-05-09 1998-05-08 Measurement of microwave radiation
NO995463A NO995463L (en) 1997-05-09 1999-11-08 Measurement of microwave radiation

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB9709299A GB2325053A (en) 1997-05-09 1997-05-09 Measurement of microwave radiation

Publications (2)

Publication Number Publication Date
GB9709299D0 GB9709299D0 (en) 1997-06-25
GB2325053A true GB2325053A (en) 1998-11-11

Family

ID=10811963

Family Applications (1)

Application Number Title Priority Date Filing Date
GB9709299A Withdrawn GB2325053A (en) 1997-05-09 1997-05-09 Measurement of microwave radiation

Country Status (6)

Country Link
EP (1) EP0980530A1 (en)
JP (1) JP2000513106A (en)
CA (1) CA2288860A1 (en)
GB (1) GB2325053A (en)
NO (1) NO995463L (en)
WO (1) WO1998052058A1 (en)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2189029A (en) * 1986-04-14 1987-10-14 Max Planck Gesellschaft Microwave calorimeter
US4968150A (en) * 1988-03-02 1990-11-06 Asea Brown Boveri Ltd. Process and arrangement for measuring the energy of a microwave pulse
GB2253519A (en) * 1990-09-07 1992-09-09 Univ Loughborough Reconfigurable frequency selective surfaces

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB8902415D0 (en) * 1989-02-03 1989-03-22 Varilab Ab Sensor
GB2246474A (en) * 1990-07-24 1992-01-29 British Aerospace A layered frequency selective surface assembly

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2189029A (en) * 1986-04-14 1987-10-14 Max Planck Gesellschaft Microwave calorimeter
US4968150A (en) * 1988-03-02 1990-11-06 Asea Brown Boveri Ltd. Process and arrangement for measuring the energy of a microwave pulse
GB2253519A (en) * 1990-09-07 1992-09-09 Univ Loughborough Reconfigurable frequency selective surfaces

Also Published As

Publication number Publication date
GB9709299D0 (en) 1997-06-25
CA2288860A1 (en) 1998-11-19
WO1998052058A1 (en) 1998-11-19
NO995463L (en) 2000-01-10
NO995463D0 (en) 1999-11-08
JP2000513106A (en) 2000-10-03
EP0980530A1 (en) 2000-02-23

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Legal Events

Date Code Title Description
WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)