EP0980529A1 - Apparatus for the measurement of microwave radiation - Google Patents
Apparatus for the measurement of microwave radiationInfo
- Publication number
- EP0980529A1 EP0980529A1 EP98920653A EP98920653A EP0980529A1 EP 0980529 A1 EP0980529 A1 EP 0980529A1 EP 98920653 A EP98920653 A EP 98920653A EP 98920653 A EP98920653 A EP 98920653A EP 0980529 A1 EP0980529 A1 EP 0980529A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- resistive element
- source
- microwave radiation
- measurement
- microwave
- 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- Withdrawn
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R29/00—Arrangements for measuring or indicating electric quantities not covered by groups G01R19/00 - G01R27/00
- G01R29/08—Measuring electromagnetic field characteristics
Definitions
- This invention relates to measurement of microwave energy and has particular application to the measurement of brief, intense microwave pulses.
- source comprises; a resistive element, and means for coupling microwave radiation from the source to the resistive element.
- the resistive element may conveniently take the form of an electrically conducting track or semi-conducting track deposited on a suitable insulating substrate.
- the coupling means may comprise an antenna and microstrip transmission line.
- electrical circuit means may be provided for measuring the electrical resistance of said element.
- resistance can be monitored as a function of temperature.
- frequency selective filter can be located between the antenna
- This feature allows the measurement of microwave energy within a particular band of frequencies.
- the energy coupled to the resistive element via the coupling means causes heating of the element.
- This heating effect may be sufficient to vaporise the element completely and permanently, to melt it temporarily or to bring about a temperature-dependent change in resistance without altering its physical state.
- Vaporisation or melting and re-freezing of the element can be determined by visual inspection (with the aid of a microscope if necessary).
- vaporisation, melting and refreezing or a temperature-dependent change in resistance can be monitored by measuring the electrical resistance of the element.
- Suitable electrical circuitry for doing this could comprise a constant
- Figure 1 is a schematic plan view of a resistive element formed on a substrate in accordance with the invention
- FIG. 2 is a schematic circuit diagram of apparatus for the measurement of microwave radiation in accordance with the invention.
- Figure 3 is a schematic diagram of a second, alternative embodiment.
- Figure 1 shows a silicon wafer 1 which acts as a mechanical support. On top of the silicon wafer 1 is spun a layer of polyimide 2.
- the polyimide layer 2 acts as an electrical and thermal insulator.
- Aluminium pads 4 are deposited at either end of the
- insulator such as
- Polyimide may be applied over the metal track and pads.
- Polyimide has the advantage of a greater dielectric
- Each connecting wire 5 is connected via one of two capacitors Cl and C2 to a transmission line 6 whose end remote from the resistive element 3 terminates in an antenna 7.
- the antenna 7 can be any conventional device receptive to the microwave frequencies
- Each connecting wire 5 is also connected, via one of two inductors LI and L2 to a constant current source 8.
- a DC voltmeter 9 monitors the voltage across the resistive element 3.
- the purpose of the inductors LI and L2 is to isolate the constant current source 8 and voltmeter 9 from the microwave
- the capacitors Cl and C2 isolate the transmission line 6
- the dimensions of the resistive element 3 are the dimensions of the resistive element 3
- a short and intense microwave pulse is emitted from a remote microwave source 10.
- Microwave energy detected by the antenna 7 is coupled into the resistive element 3 via the transmission line 6 and causes sufficient heating for the element to vaporise. Once the element has vaporised, the voltmeter will indicate that an open circuit exists. (Alternatively this can be inferred from visual inspection of the element ) .
- duration of a pulse is just enough to melt the element.
- the resistive element is designed so that it will not melt at the anticipated heating levels.
- the resistance value of the element 3, monitored by the voltmeter 9 changes as a function of temperature.
- measured resistance value gives an indication of the energy received by the element 3 from the remote source 10.
- the apparatus can be any one of the two modes of operation. In this third mode of operation, the apparatus can be any one of the two modes of operation.
- the substrate does not act as an effective heat sink.
- the substrate 1 is provided
- Figure 3 shows a further embodiment of the invention in which a second resistive element 11 is included on the same substrate 1 as the first element 3.
- This second element 11 is not coupled to the radiation source 10 but is connected to a constant current source 12 and DC voltmeter 13. Any fluctuations in ambient temperature are monitored by measuring resistance changes in the element 11 by the voltmeter 13. These measurements can then be used to compensate for resistance changes in the radiation sensitive element 3 due to
- a frequency selective filter shown ghosted in Figure 2 and 3 and designated 14 may be placed between said
- the frequency selective filter comprises a
- 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 .
- Such a filter may be incorporated with either of the embodiments of Figures 2 or 3 and employed in any of the three modes of operation described above.
Landscapes
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- General Physics & Mathematics (AREA)
- Variable-Direction Aerials And Aerial Arrays (AREA)
- Measurement Of Resistance Or Impedance (AREA)
- Investigating Or Analyzing Materials Using Thermal Means (AREA)
- Testing Or Measuring Of Semiconductors Or The Like (AREA)
Abstract
Apparatus for measuring the power of intense microwave pulses comprises a conducting track (3) formed on an insulating substrate (1, 2) and coupled to radiation from a remote source (10) via an antenna (7) and transmission line (6). The subsequent heating of the track (3) brings about a change in its resistance, which is monitored by a constant current source (8) and voltmeter (9). The degree of resistance change gives an indication of the energy content of the microwave pulse.
Description
APPARATUS FOR THE MEASUREMENT OF MICROWAVE RADIATION
This invention relates to measurement of microwave energy and 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 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 of requiring no
triggering mechanism.
According to the- present invention, apparatus for the measurement of microwave radiation emanating from a remote
source comprises; a resistive element, and means for coupling microwave radiation from the source to the resistive element.
The resistive element may conveniently take the form of an electrically conducting track or semi-conducting track deposited on a suitable insulating substrate.
The coupling means may comprise an antenna and microstrip transmission line.
Optionally, electrical circuit means may be provided for measuring the electrical resistance of said element.
As a further option, any fluctuations in ambient
temperature in the vicinity of the resistive element may be recorded by providing a further resistive device whose
resistance can be monitored as a function of temperature.
In some applications it may be desirable to band-limit
the radiation received by the antenna. In such cases a
frequency selective filter can be located between the antenna
and the remote source. This feature allows the measurement of microwave energy within a particular band of frequencies.
When a pulse of_ microwave energy is emitted by the
source, the energy coupled to the resistive element via the coupling means causes heating of the element.
This heating effect may be sufficient to vaporise the element completely and permanently, to melt it temporarily or to bring about a temperature-dependent change in resistance without altering its physical state.
Vaporisation or melting and re-freezing of the element can be determined by visual inspection (with the aid of a microscope if necessary).
Alternatively, vaporisation, melting and refreezing or a temperature-dependent change in resistance can be monitored by measuring the electrical resistance of the element. Suitable electrical circuitry for doing this could comprise a constant
current source and a voltmeter.
Whether the element vaporises, melts or merely heats up depends on its resistivity and the strength of the microwave
source, these values being a matter of design choice.
The vaporisation and melting thresholds and the
resistance variation with temperature for a particular element
can be determined by calculation or by a calibration
procedure.
Some embodiments of the invention will now be described, by way of example only, with reference to the drawings of which;
Figure 1 is a schematic plan view of a resistive element formed on a substrate in accordance with the invention,
Figure 2 is a schematic circuit diagram of apparatus for the measurement of microwave radiation in accordance with the invention, and
Figure 3 is a schematic diagram of a second, alternative embodiment.
It is convenient to employ microfabrication techniques in
the construction of the resistive element and therefore Figure 1 shows a silicon wafer 1 which acts as a mechanical support. On top of the silicon wafer 1 is spun a layer of polyimide 2.
The polyimide layer 2 acts as an electrical and thermal insulator.
On to the polyimide layer 2 is deposited a titanium track
which forms the resistive element 3.
Aluminium pads 4 are deposited at either end of the
titanium track 3 and connecting wires 5 are bonded to the pads 4.
Optionally a further layer of insulator, such as
polyimide, may be applied over the metal track and pads.
Polyimide has the advantage of a greater dielectric
strength and therefore a higher break-down voltage than air.
Referring now to Figure 2. Each connecting wire 5 is connected via one of two capacitors Cl and C2 to a transmission line 6 whose end remote from the resistive element 3 terminates in an antenna 7. The antenna 7 can be any conventional device receptive to the microwave frequencies
of interest.
Each connecting wire 5 is also connected, via one of two inductors LI and L2 to a constant current source 8. A DC voltmeter 9 monitors the voltage across the resistive element 3.
The purpose of the inductors LI and L2 is to isolate the constant current source 8 and voltmeter 9 from the microwave
signal flowing through the resistive element 3.
The capacitors Cl and C2 isolate the transmission line 6
from the DC current provided by the constant current source 8.
Certain types of antennna may not dictate a need for
these capacitors, however.
Preferably the dimensions of the resistive element 3 are
chosen so that its electrical impedance matches that of the
transmission line 6 e.g. 50ohms.
In a first mode of operation, a short and intense microwave pulse is emitted from a remote microwave source 10.
Microwave energy detected by the antenna 7 is coupled into the resistive element 3 via the transmission line 6 and causes sufficient heating for the element to vaporise. Once the element has vaporised, the voltmeter will indicate that an open circuit exists. (Alternatively this can be inferred from visual inspection of the element ) .
This will give an indication that the electrical energy deposited in the resistive element 3 has exceeded a certain threshold.
It will be evident that in this mode of operation the apparatus is used as a one-shot device.
In the second mode of operation, the heating energy coupled into the element 3 from the remote source 10 for the
duration of a pulse is just enough to melt the element.
It can be shown by calculation that the energy required to melt a resistive element is typically a tenth of that
required to vaporise it.
It has also been observed that when the resistive element
melts then refreezes, a change in its geometrical configuration occurs. This change may be detectable by
visual inspection. However it has also been observed that
this change in geometrical configuration gives rise to a permanent change in the resistance. Thus by measuring the resistance of the element 3 before and after application of a microwave pulse, one can ascertain whether or not the melting threshold has been exceeded.
In a third mode of operation, the resistive element is designed so that it will not melt at the anticipated heating levels.
In this case, the resistance value of the element 3, monitored by the voltmeter 9 changes as a function of temperature. Thus, measured resistance value gives an indication of the energy received by the element 3 from the remote source 10.
In this third mode of operation, the apparatus can be
reused indefinitely.
For each mode of operation, it is preferred that the
heating process is confined to the resistive element i.e. that
the substrate does not act as an effective heat sink.
Therefore, it is recommended that the substrate 1 is provided
with an insulator which has a long thermal time scale compared
with the length of the microwave pulses of interest.
Polyimide fulfils this role for some applications.
Figure 3 shows a further embodiment of the invention in which a second resistive element 11 is included on the same substrate 1 as the first element 3. This second element 11 is not coupled to the radiation source 10 but is connected to a constant current source 12 and DC voltmeter 13. Any fluctuations in ambient temperature are monitored by measuring resistance changes in the element 11 by the voltmeter 13. These measurements can then be used to compensate for resistance changes in the radiation sensitive element 3 due to
ambient temperature fluctuations.
In some applications it may be desirable to band-limit the microwave frequencies incident on the antenna 7 from the
remote source 10.
If so, a frequency selective filter shown ghosted in Figure 2 and 3 and designated 14 may be placed between said
antenna 7 and source 10.
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 .
Such a filter may be incorporated with either of the embodiments of Figures 2 or 3 and employed in any of the three modes of operation described above.
Claims
1. Apparatus for the measurement of microwave radiation emanating from a remote source comprising:
a resistive element, and means for coupling microwave radiation from the source to
the resistive element.
2. Apparatus according to claim 1 in which the
resistive element is an electrically conducting track formed on an insulating substrate.
3. Apparatus according to claim 2 in which the insulating substrate includes a layer of polyimide.
4. Apparatus according to any preceding claim in which
the means for coupling microwave radiation from the source to
the resistive element comprises an antenna and microstrip
transmission line.
5. Apparatus according to any preceding claim and
including means for measuring the electrical resistance of the
resistive element.
6. Apparatus according to claim 5 in which the means
for measuring the electrical resistance of the resistive
element comprise a constant current source and a voltmeter.
7. Apparatus according to any preceding claim and
including a resistive device, sensitive to ambient temperature fluctuations, and means for monitoring the resistance of said
device.
8. Apparatus according to any preceding claim and further including a frequency selective filter for band-limiting the radiation received by the resistive element from the remote source.
9. Apparatus according to claim 9 in which the
frequency selective filter comprises at least one dielectric substrate on which is printed an array of electrically conducting elements.
10. Apparatus for the measurement of microwave radiation
substantially as hereinbefore described with reference to the
drawings.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB9709306A GB2325054A (en) | 1997-05-09 | 1997-05-09 | Apparatus for the measurement of microwave radiation |
GB9709306 | 1997-05-09 | ||
PCT/GB1998/001326 WO1998052056A1 (en) | 1997-05-09 | 1998-05-08 | Apparatus for the measurement of microwave radiation |
Publications (1)
Publication Number | Publication Date |
---|---|
EP0980529A1 true EP0980529A1 (en) | 2000-02-23 |
Family
ID=10811967
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP98920653A Withdrawn EP0980529A1 (en) | 1997-05-09 | 1998-05-08 | Apparatus for the measurement of microwave radiation |
Country Status (6)
Country | Link |
---|---|
EP (1) | EP0980529A1 (en) |
JP (1) | JP2000513105A (en) |
CA (1) | CA2288660A1 (en) |
GB (1) | GB2325054A (en) |
NO (1) | NO995464L (en) |
WO (1) | WO1998052056A1 (en) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CZ301885B6 (en) * | 2007-11-19 | 2010-07-21 | Ceské vysoké ucení technické - Fakulta elektrotechnická | Antenna matrix for measuring distribution of electromagnetic field intensity |
US10145938B2 (en) | 2014-04-26 | 2018-12-04 | Infineon Technologies Ag | Power sensor for integrated circuits |
CN112285434B (en) * | 2020-10-29 | 2022-04-22 | 中国舰船研究设计中心 | High-power microwave effect test system and method with monitoring and positioning functions |
Family Cites Families (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3575657A (en) * | 1969-05-14 | 1971-04-20 | Us Navy | Microwave detector mount and power bridge circuit |
CA1038035A (en) * | 1974-08-05 | 1978-09-05 | David L. Hollway | Microwave alarm |
US4044303A (en) * | 1975-11-10 | 1977-08-23 | John Reindel | Microwave radiation detector |
GB2031167A (en) * | 1978-09-18 | 1980-04-16 | Meyed Aluminium Ltd | Microwave detecting device |
US4539567A (en) * | 1983-09-12 | 1985-09-03 | Micrometrics, Ltd. | Microwave monitor |
US4752730A (en) * | 1985-10-28 | 1988-06-21 | The Narda Microwave Corp. | Radiation monitor diode detector with constant efficiency for both CW and pulsed signals |
GB9019628D0 (en) * | 1990-09-07 | 1992-04-08 | Univ Loughborough | Reconfigurable frequency selective surface |
US5171733A (en) * | 1990-12-04 | 1992-12-15 | The Regents Of The University Of California | Antenna-coupled high Tc superconducting microbolometer |
-
1997
- 1997-05-09 GB GB9709306A patent/GB2325054A/en not_active Withdrawn
-
1998
- 1998-05-08 JP JP10548899A patent/JP2000513105A/en active Pending
- 1998-05-08 WO PCT/GB1998/001326 patent/WO1998052056A1/en not_active Application Discontinuation
- 1998-05-08 EP EP98920653A patent/EP0980529A1/en not_active Withdrawn
- 1998-05-08 CA CA002288660A patent/CA2288660A1/en not_active Abandoned
-
1999
- 1999-11-08 NO NO995464A patent/NO995464L/en not_active Application Discontinuation
Non-Patent Citations (1)
Title |
---|
See references of WO9852056A1 * |
Also Published As
Publication number | Publication date |
---|---|
NO995464D0 (en) | 1999-11-08 |
GB9709306D0 (en) | 1997-06-25 |
WO1998052056A1 (en) | 1998-11-19 |
GB2325054A (en) | 1998-11-11 |
NO995464L (en) | 2000-01-10 |
CA2288660A1 (en) | 1998-11-19 |
JP2000513105A (en) | 2000-10-03 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
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17P | Request for examination filed |
Effective date: 19991021 |
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AK | Designated contracting states |
Kind code of ref document: A1 Designated state(s): DE ES FR GB IT SE |
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17Q | First examination report despatched |
Effective date: 20000707 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN |
|
18D | Application deemed to be withdrawn |
Effective date: 20001118 |