CA2255810A1 - Apparatus for and method of testing electronic devices for electromagnetic interference - Google Patents
Apparatus for and method of testing electronic devices for electromagnetic interference Download PDFInfo
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- CA2255810A1 CA2255810A1 CA 2255810 CA2255810A CA2255810A1 CA 2255810 A1 CA2255810 A1 CA 2255810A1 CA 2255810 CA2255810 CA 2255810 CA 2255810 A CA2255810 A CA 2255810A CA 2255810 A1 CA2255810 A1 CA 2255810A1
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Abstract
An apparatus and method are provided, for carrying out electromagnetic interference testing of electronic devices, such as hearing aids. The apparatus has a device for holding an electronic device stationary and an antenna holder for holding an antenna for providing a source of electromagnetic radiation and for moving the antenna around the electronic device, e.g. through a hemispherical surface. The apparatus is intended to be suitable for testing for bystander interference and also for near field or user interference, which can be caused by cellular telephones and the like.
Description
B&P File No.: 680-165 BERESKIN & PARK CANADA
Title: Apparatus for and Method of Testing Electronic Devices for Electromagnetic Interference Inventor: Marco Candiago Title: Apparatus for and Method of Testing Electronic Devices for Electromagnetic Interference FIELD OF THE INVENTION
This invention relates to a test apparatus and to a method for measuring the susceptibility of electronic devices, particularly hearing aids, to electromagnetic interference (EMI).
BACKGROUND OF THE INVENTION
Awareness of the problems of electromagnetic interference (EMI) continue to increase, with the ever increasing number of electronic and electrical devices in use. Various proposals have been made for testing susceptibility of electronic devices to transmitted RF fields. The intention is to determine whether any particular device will experience problems when exposed to RF fields which it will likely encounter in normal use.
A particular problem can arise with medical devices.
Malfunction of such devices, e.g. heart and pace makers and the like can be fatal. For other devices, such as hearing aids, the consequences of EMI may not be fatal, but can be extremely unpleasant to users. For example, it can result in a hearing aid emitting a variety of sounds at high volumes, which can make users reluctant to use them. With increased awareness of this EMI problem for hearing aids, the European economic community (EEC) in 1998 has proposed a harmonized standard (IEC 118-13) which sets out minimum immunity levels for a hearing aid. This is one of many requirements that the hearing aid must pass in order to obtain a "CE" mark, and this is required for hearing aids marketed in Europe ("CE" is a French acronym for European Certification).
In North America in 1996, a summit meeting between three working groups (people with hearing loss, hearing aid manufacturers and the digital wireless telephone industry), was formed to investigate the issue of EMI interference, and to address various perceived shortcomings of the European standard. The American National Standards Institute (ANSI) established a committee or group C63, which in turn established a task group (TC C63.19), to develop standards in cooperation with representatives of the three main groups and other interested parties. This task group is seeking to develop a North American standard which not only addresses issues of bystander interference, i.e. interference to a hearing aid wearer caused by use of a digital cellular telephone by someone else in relatively close proximity, with which the European standard exclusively deals, but also with user or near field interference as well which a hearing aid wearer will experience when using a digital cellular telephone and other devices.
Fundamentally, when measuring EMI for a hearing aid or other device, there is a requirement to move an antenna transmitting an RF signal at a selected frequency relative to the device under investigation.
Often, the antenna is kept stationary and the device under investigation is moved relative to it. This is a technique that has been applied for hearing aids. This has a number of disadvantages. For a hearing aid, it is necessary to have an acoustic tube connected to the hearing aid, so that the acoustic output of the hearing aid, in response to the EMI radiation can be measured.
This becomes difficult if the hearing aid is moved about. Additionally, techniques with a stationary antenna do not permit full spherical motion for the hearing aid about the antenna.
SUMMARY OF THE INVENTION
In accordance with first aspect of the present invention, there is provided an apparatus, for carrying out electromagnetic interference testing of electronic devices, the apparatus comprising:
a device holding means for holding an electronic device stationary; and an antenna means for holding an antenna for providing a source of electromagnetic radiation and for moving the antenna around the electronic device.
Advantageously, the antenna means for holding and displacing the antenna is configured to move the antenna in a spherical surface centered on the electronic device. Preferably, the antenna means for holding and displacing the antenna comprises a generally cylindrical support ring for adjusting the angular position of the antenna in a horizontal plane, and a support means extending from the support ring for adjusting the vertical angle of the antenna. The support means can comprise a yolk extending through an arc centered on the device holding means, and slidably mounted on the support ring, and an antenna holder movably mounted on the yolk.
Conveniently, the antenna holder is slidably mounted to the yolk, the slidable mount being such as to frictionally retain the antenna holder in position.
Preferably, the main body of the antenna holder includes a central opening for a central shaft of an antenna, and the locking means comprises a locking member slidably mounted in an aperture, for movement transversely of the central opening, the locking member including an opening corresponding to the central opening of the main body, and spring biassing means, biassing the opening of the locking member out of alignment with the central opening, whereby, in use, with a central shaft of an antenna located in the central opening, the locking member is biased against a central shaft, to secure the central shaft in position.
More preferably, the device holding means includes a stationary cross member mounted on the base, and a mount, the mount being mounted on the cross member and including moveable jaws for securing an electronic device. Further, there can be provided screw members, mounting the stationary cross member to the base, to permit the vertical position of the stationary cross member to be adjusted. The mount is preferably movably mounted on the stationary cross member to enable the lateral position of the mount to be adjusted.
Another aspect of the present invention provides a method of measuring the susceptibility of an electronic device to electromagnetic interference, the method comprising the steps of:
(1) mounting the electronic device in a stationary position;
(2) providing an antenna and providing antenna with a desired high frequency electromagnetic signal;
(3) traversing the antenna through a desired series of positions relative to the electronic device; and (4) making a measurement of the electromagnetic interference detected at the device for each position of the antenna.
A further variant, applicable to both the apparatus and method, is to provide a stationary aerial, and then mount the hearing aid or other device for movement around it.
Preferably, the antenna is moved through a plurality of positions located substantially in a spherical surface centered on the electronic device.
More preferably, the method is applied to a hearing aid, and step (4) then comprises detecting the acoustic output of the hearing aid, to determine the effects of electromagnetic interference.
BRIEF DESCRIPTION OF THE DRAWING FIGURES
For a better understanding of the present invention and to show more clearly how it may be carried into effect, reference will now be made, by way of example, to the accompanying drawings in which:
Figure 1 is a schematic view showing conventional spherical coordinates;
Figure 2 is a perspective view of an apparatus in accordance with the present invention;
Figure 3 is a perspective view of an antenna holder for use with the apparatus of the present invention; and Figure 4 is a detail showing connection of a dipole antenna.
Title: Apparatus for and Method of Testing Electronic Devices for Electromagnetic Interference Inventor: Marco Candiago Title: Apparatus for and Method of Testing Electronic Devices for Electromagnetic Interference FIELD OF THE INVENTION
This invention relates to a test apparatus and to a method for measuring the susceptibility of electronic devices, particularly hearing aids, to electromagnetic interference (EMI).
BACKGROUND OF THE INVENTION
Awareness of the problems of electromagnetic interference (EMI) continue to increase, with the ever increasing number of electronic and electrical devices in use. Various proposals have been made for testing susceptibility of electronic devices to transmitted RF fields. The intention is to determine whether any particular device will experience problems when exposed to RF fields which it will likely encounter in normal use.
A particular problem can arise with medical devices.
Malfunction of such devices, e.g. heart and pace makers and the like can be fatal. For other devices, such as hearing aids, the consequences of EMI may not be fatal, but can be extremely unpleasant to users. For example, it can result in a hearing aid emitting a variety of sounds at high volumes, which can make users reluctant to use them. With increased awareness of this EMI problem for hearing aids, the European economic community (EEC) in 1998 has proposed a harmonized standard (IEC 118-13) which sets out minimum immunity levels for a hearing aid. This is one of many requirements that the hearing aid must pass in order to obtain a "CE" mark, and this is required for hearing aids marketed in Europe ("CE" is a French acronym for European Certification).
In North America in 1996, a summit meeting between three working groups (people with hearing loss, hearing aid manufacturers and the digital wireless telephone industry), was formed to investigate the issue of EMI interference, and to address various perceived shortcomings of the European standard. The American National Standards Institute (ANSI) established a committee or group C63, which in turn established a task group (TC C63.19), to develop standards in cooperation with representatives of the three main groups and other interested parties. This task group is seeking to develop a North American standard which not only addresses issues of bystander interference, i.e. interference to a hearing aid wearer caused by use of a digital cellular telephone by someone else in relatively close proximity, with which the European standard exclusively deals, but also with user or near field interference as well which a hearing aid wearer will experience when using a digital cellular telephone and other devices.
Fundamentally, when measuring EMI for a hearing aid or other device, there is a requirement to move an antenna transmitting an RF signal at a selected frequency relative to the device under investigation.
Often, the antenna is kept stationary and the device under investigation is moved relative to it. This is a technique that has been applied for hearing aids. This has a number of disadvantages. For a hearing aid, it is necessary to have an acoustic tube connected to the hearing aid, so that the acoustic output of the hearing aid, in response to the EMI radiation can be measured.
This becomes difficult if the hearing aid is moved about. Additionally, techniques with a stationary antenna do not permit full spherical motion for the hearing aid about the antenna.
SUMMARY OF THE INVENTION
In accordance with first aspect of the present invention, there is provided an apparatus, for carrying out electromagnetic interference testing of electronic devices, the apparatus comprising:
a device holding means for holding an electronic device stationary; and an antenna means for holding an antenna for providing a source of electromagnetic radiation and for moving the antenna around the electronic device.
Advantageously, the antenna means for holding and displacing the antenna is configured to move the antenna in a spherical surface centered on the electronic device. Preferably, the antenna means for holding and displacing the antenna comprises a generally cylindrical support ring for adjusting the angular position of the antenna in a horizontal plane, and a support means extending from the support ring for adjusting the vertical angle of the antenna. The support means can comprise a yolk extending through an arc centered on the device holding means, and slidably mounted on the support ring, and an antenna holder movably mounted on the yolk.
Conveniently, the antenna holder is slidably mounted to the yolk, the slidable mount being such as to frictionally retain the antenna holder in position.
Preferably, the main body of the antenna holder includes a central opening for a central shaft of an antenna, and the locking means comprises a locking member slidably mounted in an aperture, for movement transversely of the central opening, the locking member including an opening corresponding to the central opening of the main body, and spring biassing means, biassing the opening of the locking member out of alignment with the central opening, whereby, in use, with a central shaft of an antenna located in the central opening, the locking member is biased against a central shaft, to secure the central shaft in position.
More preferably, the device holding means includes a stationary cross member mounted on the base, and a mount, the mount being mounted on the cross member and including moveable jaws for securing an electronic device. Further, there can be provided screw members, mounting the stationary cross member to the base, to permit the vertical position of the stationary cross member to be adjusted. The mount is preferably movably mounted on the stationary cross member to enable the lateral position of the mount to be adjusted.
Another aspect of the present invention provides a method of measuring the susceptibility of an electronic device to electromagnetic interference, the method comprising the steps of:
(1) mounting the electronic device in a stationary position;
(2) providing an antenna and providing antenna with a desired high frequency electromagnetic signal;
(3) traversing the antenna through a desired series of positions relative to the electronic device; and (4) making a measurement of the electromagnetic interference detected at the device for each position of the antenna.
A further variant, applicable to both the apparatus and method, is to provide a stationary aerial, and then mount the hearing aid or other device for movement around it.
Preferably, the antenna is moved through a plurality of positions located substantially in a spherical surface centered on the electronic device.
More preferably, the method is applied to a hearing aid, and step (4) then comprises detecting the acoustic output of the hearing aid, to determine the effects of electromagnetic interference.
BRIEF DESCRIPTION OF THE DRAWING FIGURES
For a better understanding of the present invention and to show more clearly how it may be carried into effect, reference will now be made, by way of example, to the accompanying drawings in which:
Figure 1 is a schematic view showing conventional spherical coordinates;
Figure 2 is a perspective view of an apparatus in accordance with the present invention;
Figure 3 is a perspective view of an antenna holder for use with the apparatus of the present invention; and Figure 4 is a detail showing connection of a dipole antenna.
DETAILED DESCRIPTION OF THE INVENTION
Figure 1 shows schematically conventional spherical coordinates. In known manner, there is a radius factor R extending from an origin to a point in a spherical surface. The distances from the origin is determined by the length of the vector or radius. The angular position in an horizontal plane is indicated by the angle 8, and the angle for the vertical is indicated by ~.
Referring now to Figure 2, there is shown an apparatus i n accordance with the present invention generally designated by the reference 10. The apparatus 10 has a base 12. The base is cut in the form of a symmetrical cross, and includes a central vertical bore 14. In known manner, this bore 14 is fitted with a tapped or threaded metal insert, for mounting the apparatus 10 on a non-metallic tripod (not shown). The base 12, as for all components of the apparatus 10, is formed from UHMW, a type of polyethylene, selected for its low dielectric constant (2.3) and reasonable cost.
At either end of one of the arms of the cross or the base 12, there are two threaded bores in which are located two screw members 16.
Each screw member 16 comprises a threaded shaft 17 and an engagement knob 18, located below the base 12.
A stationary cross member 20 is located on the ends of the threaded shafts 17. The threaded shafts 17 are attached to the cross member 20 in a fashion that allows them to be rotated freely while remaining attached to the cross member 20. The base 12 contains holes with tapped threads of the same pitch of the threaded shafts 17 which are subsequently threaded through these tapped holes. Upon simultaneous clockwise or counter-clockwise rotation of the two threaded shafts 17, the cross member 20 will be moved vertically up or down.
In the center of the cross member 20, there is a hearing aid mount 22. A shallow slot in the base of the hearing aid mount 22 engages an elongate projection 24 along the top of the cross member 20, to permit the hearing aid mount to be displaced along the cross member 20. The mount 22 can also be rotated relative to the cross member 20.
The mount 20 includes a pair of jaws 26, one of which is stationary and the other of which engages a threaded shaft of a screw element 28, for displacing the jaws 26 relative to one another, to enable a hearing aid to be clamped and released.
A support ring 30 is mounted by a plurality of short columns 32 above the base 12. These columns 12 are 2.2 cm in length, to space the ring 30 by the distance above the base 12. The ring 30 is cylindrical and of uniform thickness radially and of uniform height in the vertical direction.
A yolk 34 is generally semi-circular. The yolk 34 includes lower ends 36, each provided with a slot 38. The slot is curved and corresponds to the radius of the support ring 30, to enable the yolk 34 to be rotated freely about a vertical axis on the ring 30.
Above the lower ends 36, the yolk 34 includes side slots 40, a top slot 42 and a bottom slot 44, separating four separate arcuate portions 46 from one another.
The slots 40, 42 and 44 extend through slightly more than 180°, so that the center of an antenna holder, detailed below, can traverse through a full 180°.
Referring now to Figure 3, the antenna holder is designated by the reference 50, and from the side has a generally arcuate shape, with radii corresponding to those of the yolk 34. The antenna holder 50 includes a central body portion 52 having a width corresponding to the width of the top and bottom slots 42, 44 and having radially inner and outer surfaces corresponding to the radially inner and outer surfaces of the arcuate portions 46, i.e. so as to be substantially flush with the inner and outer surfaces of the accede portions 46. On either side of the main body 52, there is a side projections or flanges 54, which has a curved profile corresponding to the side slots 40. Again, the width of these side projections 54 is such that they are substantially flush with side faces of the arcuate _7_ portions 46.
At the center of the antenna holder 50, there is a central opening 56 extending through the main body 52. Extending from one end of the main body 52 and perpendicular to the central opening 56, there is an aperture 58 of substantially rectangular cross-section. A locking member 60 is located in this aperture 58. The locking member 60 has an opening 62, corresponding to the central opening 56. A spring 64 biases the locking member 60 in that direction out of the aperture 58, so as to displace the opening 62 from alignment with a central opening 56. In use, when an antenna is located in the central opening 56, this spring action presses the locking member 60 against one side of the antenna, effectively to lock the antenna in position.
A dipole antenna is indicated at 70 in Figure 2 and comprises in known manner the actual antenna elements 72 connected to a central shaft 74. A connection lead 76 extends from the upper end of the shaft 74. The shaft 74 and the connection lead 76 are fed through the central opening of the antenna holder 50, with the locking member 60 depressed to permit free insertion of the shaft 74. The connection lead 76 is then connected to a signal source.
At the center and at the end of the dipole, there are mounted distance markers 78 (Figure 3). These are also formed from UHMW polyethylene and are 1 cm long. These ensure that the aerial does not approach a hearing aid by less than 1 cm, as is required by test standards.
To hold the antenna holder in position, side plates 66 are secured by non-metallic screws to the side projections or flanges 54. The projections 54 and side plates 66 are dimensioned such that the side plates 66 frictionally engage the arcuate portions 46. This is such that the antenna holder 50 can be displaced by hand, but at the same time the frictional force is sufficient to retain the antenna holder, with the dipole antenna 70, at any set location.
The central shaft 74 of the antenna 70, at the top thereof, comprises an external body and a semi-rigid coaxial cable 80. A slide or -$-connector body 82 is also formed from UHMW polyethylene. This has an internal bore extending from one end to the other, and a female-female SMA connector 84 is located within a narrow section of this bore and secured in position by a pair of retention nuts 86. A dipole-male SMA
connector 88 is mounted on the end of the connector 84 and provides the connection to the coaxial cable 80 of the dipole. In known manner, the end of the connection lead 76 has a male connector, which as indicated connects to the other end of the female-female SMA connector 84.
In use, a hearing aid indicated schematically at 90 is located in the hearing aid mount 22 and the jaws 26 are adjusted to hold it securely.
If desired, the mount 22 is slid along the cross member 20 so that the hearing aid 90 centrally located. Similarly, depending on the dimensions of the hearing aid, the screw members 16 are adjusted, so that the hearing aid 90 is exactly at the center of the spherical surface corresponding to the yolk 34.
Then, the radial extent of the dipole antenna is adjusted, by use of the locking member 60. This is depressed, to release the dipole antenna 70, and the central shaft 74 is then slid in or out, until the desired radial extent is retained. The locking member 60 is then released.
A series of measurements at different angles of 8 and ~ can then be made. Different angles of A are obtained by rotating the yolk 34 relative to the support ring 30. For this purpose, the support ring 30 can be provided with suitable angular markings. The angle ~ adjustment is obtained by sliding the antenna holder 50 along the yolk 34. Again, at least one of the arcuate portions 46 can be marked to indicate the angular position of ~.
In this manner, any desired sets of coordinates (R, 8, ~) can be obtained in a hemisphere. To obtain readings in the complementary hemisphere, it is simply necessary to release the hearing aid or other device from the mount 22 and invert it.
For this apparatus, a hearing aid can be tested for only directional immunity to near field high frequency electric and magnetic fields. It is preferred for the hearing aid to be held stationary by a clamping mechanism and the dipole is to move around the hearing aid. The dipole antenna 70 is provided with 1 cm distance markers attached to the center and to the ends so no part of the dipole will come closer than 1 cm to the hearing aid as defined by the currently developing C63.19-19XX standard.
The apparatus is advantageous as compared to other current devices, in that the hearing aid, which has acoustic tubing attached to it and is not easily rotated is held stationary, while the radiating dipole antenna 70 is moved around it. However, for some applications, it may be preferred to hold the dipole stationary on the mount 22, and to mount the hearing aid on the holder 50, modified for that purpose.
The dipole antenna 70 can be readily exchanged, by detaching it from the antenna holder 50, and passing its connection lead 76 through the opening 56. The apparatus 10 allows for accurate positioning of the dipole antenna 70, so that repeatable EMI measurements can be made.
Figure 1 shows schematically conventional spherical coordinates. In known manner, there is a radius factor R extending from an origin to a point in a spherical surface. The distances from the origin is determined by the length of the vector or radius. The angular position in an horizontal plane is indicated by the angle 8, and the angle for the vertical is indicated by ~.
Referring now to Figure 2, there is shown an apparatus i n accordance with the present invention generally designated by the reference 10. The apparatus 10 has a base 12. The base is cut in the form of a symmetrical cross, and includes a central vertical bore 14. In known manner, this bore 14 is fitted with a tapped or threaded metal insert, for mounting the apparatus 10 on a non-metallic tripod (not shown). The base 12, as for all components of the apparatus 10, is formed from UHMW, a type of polyethylene, selected for its low dielectric constant (2.3) and reasonable cost.
At either end of one of the arms of the cross or the base 12, there are two threaded bores in which are located two screw members 16.
Each screw member 16 comprises a threaded shaft 17 and an engagement knob 18, located below the base 12.
A stationary cross member 20 is located on the ends of the threaded shafts 17. The threaded shafts 17 are attached to the cross member 20 in a fashion that allows them to be rotated freely while remaining attached to the cross member 20. The base 12 contains holes with tapped threads of the same pitch of the threaded shafts 17 which are subsequently threaded through these tapped holes. Upon simultaneous clockwise or counter-clockwise rotation of the two threaded shafts 17, the cross member 20 will be moved vertically up or down.
In the center of the cross member 20, there is a hearing aid mount 22. A shallow slot in the base of the hearing aid mount 22 engages an elongate projection 24 along the top of the cross member 20, to permit the hearing aid mount to be displaced along the cross member 20. The mount 22 can also be rotated relative to the cross member 20.
The mount 20 includes a pair of jaws 26, one of which is stationary and the other of which engages a threaded shaft of a screw element 28, for displacing the jaws 26 relative to one another, to enable a hearing aid to be clamped and released.
A support ring 30 is mounted by a plurality of short columns 32 above the base 12. These columns 12 are 2.2 cm in length, to space the ring 30 by the distance above the base 12. The ring 30 is cylindrical and of uniform thickness radially and of uniform height in the vertical direction.
A yolk 34 is generally semi-circular. The yolk 34 includes lower ends 36, each provided with a slot 38. The slot is curved and corresponds to the radius of the support ring 30, to enable the yolk 34 to be rotated freely about a vertical axis on the ring 30.
Above the lower ends 36, the yolk 34 includes side slots 40, a top slot 42 and a bottom slot 44, separating four separate arcuate portions 46 from one another.
The slots 40, 42 and 44 extend through slightly more than 180°, so that the center of an antenna holder, detailed below, can traverse through a full 180°.
Referring now to Figure 3, the antenna holder is designated by the reference 50, and from the side has a generally arcuate shape, with radii corresponding to those of the yolk 34. The antenna holder 50 includes a central body portion 52 having a width corresponding to the width of the top and bottom slots 42, 44 and having radially inner and outer surfaces corresponding to the radially inner and outer surfaces of the arcuate portions 46, i.e. so as to be substantially flush with the inner and outer surfaces of the accede portions 46. On either side of the main body 52, there is a side projections or flanges 54, which has a curved profile corresponding to the side slots 40. Again, the width of these side projections 54 is such that they are substantially flush with side faces of the arcuate _7_ portions 46.
At the center of the antenna holder 50, there is a central opening 56 extending through the main body 52. Extending from one end of the main body 52 and perpendicular to the central opening 56, there is an aperture 58 of substantially rectangular cross-section. A locking member 60 is located in this aperture 58. The locking member 60 has an opening 62, corresponding to the central opening 56. A spring 64 biases the locking member 60 in that direction out of the aperture 58, so as to displace the opening 62 from alignment with a central opening 56. In use, when an antenna is located in the central opening 56, this spring action presses the locking member 60 against one side of the antenna, effectively to lock the antenna in position.
A dipole antenna is indicated at 70 in Figure 2 and comprises in known manner the actual antenna elements 72 connected to a central shaft 74. A connection lead 76 extends from the upper end of the shaft 74. The shaft 74 and the connection lead 76 are fed through the central opening of the antenna holder 50, with the locking member 60 depressed to permit free insertion of the shaft 74. The connection lead 76 is then connected to a signal source.
At the center and at the end of the dipole, there are mounted distance markers 78 (Figure 3). These are also formed from UHMW polyethylene and are 1 cm long. These ensure that the aerial does not approach a hearing aid by less than 1 cm, as is required by test standards.
To hold the antenna holder in position, side plates 66 are secured by non-metallic screws to the side projections or flanges 54. The projections 54 and side plates 66 are dimensioned such that the side plates 66 frictionally engage the arcuate portions 46. This is such that the antenna holder 50 can be displaced by hand, but at the same time the frictional force is sufficient to retain the antenna holder, with the dipole antenna 70, at any set location.
The central shaft 74 of the antenna 70, at the top thereof, comprises an external body and a semi-rigid coaxial cable 80. A slide or -$-connector body 82 is also formed from UHMW polyethylene. This has an internal bore extending from one end to the other, and a female-female SMA connector 84 is located within a narrow section of this bore and secured in position by a pair of retention nuts 86. A dipole-male SMA
connector 88 is mounted on the end of the connector 84 and provides the connection to the coaxial cable 80 of the dipole. In known manner, the end of the connection lead 76 has a male connector, which as indicated connects to the other end of the female-female SMA connector 84.
In use, a hearing aid indicated schematically at 90 is located in the hearing aid mount 22 and the jaws 26 are adjusted to hold it securely.
If desired, the mount 22 is slid along the cross member 20 so that the hearing aid 90 centrally located. Similarly, depending on the dimensions of the hearing aid, the screw members 16 are adjusted, so that the hearing aid 90 is exactly at the center of the spherical surface corresponding to the yolk 34.
Then, the radial extent of the dipole antenna is adjusted, by use of the locking member 60. This is depressed, to release the dipole antenna 70, and the central shaft 74 is then slid in or out, until the desired radial extent is retained. The locking member 60 is then released.
A series of measurements at different angles of 8 and ~ can then be made. Different angles of A are obtained by rotating the yolk 34 relative to the support ring 30. For this purpose, the support ring 30 can be provided with suitable angular markings. The angle ~ adjustment is obtained by sliding the antenna holder 50 along the yolk 34. Again, at least one of the arcuate portions 46 can be marked to indicate the angular position of ~.
In this manner, any desired sets of coordinates (R, 8, ~) can be obtained in a hemisphere. To obtain readings in the complementary hemisphere, it is simply necessary to release the hearing aid or other device from the mount 22 and invert it.
For this apparatus, a hearing aid can be tested for only directional immunity to near field high frequency electric and magnetic fields. It is preferred for the hearing aid to be held stationary by a clamping mechanism and the dipole is to move around the hearing aid. The dipole antenna 70 is provided with 1 cm distance markers attached to the center and to the ends so no part of the dipole will come closer than 1 cm to the hearing aid as defined by the currently developing C63.19-19XX standard.
The apparatus is advantageous as compared to other current devices, in that the hearing aid, which has acoustic tubing attached to it and is not easily rotated is held stationary, while the radiating dipole antenna 70 is moved around it. However, for some applications, it may be preferred to hold the dipole stationary on the mount 22, and to mount the hearing aid on the holder 50, modified for that purpose.
The dipole antenna 70 can be readily exchanged, by detaching it from the antenna holder 50, and passing its connection lead 76 through the opening 56. The apparatus 10 allows for accurate positioning of the dipole antenna 70, so that repeatable EMI measurements can be made.
Claims (17)
1. An apparatus, for carrying out electromagnetic interference testing of electronic devices, the apparatus comprising:
a device holding means for holding an electronic device stationary; and an antenna means for holding an antenna for providing a source of electromagnetic radiation and for moving the antenna around the electronic device.
a device holding means for holding an electronic device stationary; and an antenna means for holding an antenna for providing a source of electromagnetic radiation and for moving the antenna around the electronic device.
2. An apparatus as claimed in claim 1, wherein the antenna means for holding and displacing the antenna is configured to move the antenna in a spherical surface centered on the electronic device.
3. An apparatus as claimed in claim 2, wherein the antenna means for holding and displacing the antenna comprises a generally cylindrical support ring for adjusting the angular position of the antenna in a horizontal plane, and a support means extending from the support ring for adjusting the vertical angle of the antenna.
4. An apparatus as claimed in claim 3, wherein the support means comprises a yolk extending through an arc centered on the device holding means, and slidably mounted on the support ring, and an antenna holder movably mounted on the yolk.
5. An apparatus as claimed in claim 4, wherein the antenna holder is slidably mounted to the yolk, the slidable mount being such as to frictionally retain the antenna holder in position.
6. An apparatus as claimed in claim 5, wherein the antenna holder includes locking means for holding an antenna in position.
7. An apparatus as claimed in claim 6, wherein the yolk is substantially semi-circular, and includes a pair of lower ends, and wherein each lower end includes a downwardly facing slot which engages the support ring.
8. An apparatus as claimed in claim 7, wherein the yolk comprises a plurality of arcuate portions, with top, bottom and side slots being defined between the arcuate portions, and wherein the antenna holder includes projections located in the top, bottom and side slots.
9. An apparatus as claimed in claim 8, wherein the antenna holder includes side plates secured thereto and frictionally engaging the arcuate portions, to retain the antenna holder in any desired location.
10. An apparatus as claimed in claim 9, wherein the main body of the antenna holder includes a central opening for a central shaft of an antenna, and wherein the locking means comprises a locking member slidably mounted in an aperture, for movement transversely of the central opening, the locking member including an opening corresponding to the central opening of the main body, and spring biassing means, biassing the opening of the locking member out of alignment with the central opening, whereby, in use, with a central shaft of an antenna located in the central opening, the locking member is biased against a central shaft, to secure the central shaft in position.
11. An apparatus as claimed in claim 6, which includes a base and a plurality of upwardly extending spacer elements extending between the base and the support ring, to space the support ring from the base.
12. An apparatus as claimed in claim 11, wherein the base includes a central bore, adapted for mounting on a tripod.
13. An apparatus as claimed in claim 11, which device holding means includes a stationary cross member mounted on the base, and a mount, the mount being mounted on the cross member and including moveable jaws for securing an electronic device.
14.~An apparatus as claimed in claim 13, which includes screw members, counting the stationary cross member to the base, to permit the vertical position of the stationary cross member to be adjusted.
15. An apparatus as claimed in claim 14, wherein the mount is movably counted on the stationary cross member to enable the lateral position of to mount to be adjusted.
16. A method of measuring the susceptibility of an electronic device to electromagnetic interference, the method comprising the steps of:
(1) mounting the electronic device in a stationary position;
(2) providing an antenna and providing antenna with a desired high frequency electromagnetic signal;
(3) traversing the antenna through a desired series of positions relative to the electronic device; and (4) making a measurement of the electromagnetic interference detected at the device for each position of the antenna.
16. A method as claimed in claim 15, wherein the antenna is moved through a plurality of positions located substantially in a spherical surface centered on the electronic device.
(1) mounting the electronic device in a stationary position;
(2) providing an antenna and providing antenna with a desired high frequency electromagnetic signal;
(3) traversing the antenna through a desired series of positions relative to the electronic device; and (4) making a measurement of the electromagnetic interference detected at the device for each position of the antenna.
16. A method as claimed in claim 15, wherein the antenna is moved through a plurality of positions located substantially in a spherical surface centered on the electronic device.
17. A method as claimed in claim 16, which comprises applying the method to a hearing aid, and wherein step (4) comprises detecting the acoustic output of the hearing aid, to determine the effects of electromagnetic interference.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US17562198A | 1998-10-20 | 1998-10-20 | |
| US09/175,621 | 1998-10-20 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2255810A1 true CA2255810A1 (en) | 2000-04-20 |
Family
ID=29549555
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2255810 Abandoned CA2255810A1 (en) | 1998-10-20 | 1998-12-07 | Apparatus for and method of testing electronic devices for electromagnetic interference |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2255810A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2005083834A1 (en) * | 2004-02-11 | 2005-09-09 | Sony Ericsson Mobile Communications Ab | Gsm radiated sensitivity measurement technique |
-
1998
- 1998-12-07 CA CA 2255810 patent/CA2255810A1/en not_active Abandoned
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2005083834A1 (en) * | 2004-02-11 | 2005-09-09 | Sony Ericsson Mobile Communications Ab | Gsm radiated sensitivity measurement technique |
| US7477877B2 (en) | 2004-02-11 | 2009-01-13 | Sony Ericsson Mobile Communications Ab | GSM radiated sensitivity measurement technique |
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