Electricity: measuring and testing – Impedance – admittance or other quantities representative of... – Distributive type parameters
Reexamination Certificate
2000-04-20
2002-06-25
Sherry, Michael J. (Department: 2829)
Electricity: measuring and testing
Impedance, admittance or other quantities representative of...
Distributive type parameters
C324S095000, C324S703000
Reexamination Certificate
active
06411104
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to apparatus and method for detecting an electromagnetic wave source which can detect and identify the position of the source of an unwanted electromagnetic wave (electromagnetic disturbing wave) in an electronic apparatus such as a product mounting various kinds of electronic parts on a printed board, as well as system and method for analyzing an electromagnetic wave source which can analyze whether the standards of VCCI (Voluntary Control Council for Interference by Information Technology Equipment) are satisfied.
Electromagnetic interference due to an unwanted electromagnetic wave occurs frequently concomitantly with the recent widespread use of information communication apparatus and the like and therefore, in unwanted electromagnetic radiation suppressing technology, a technique has been required which can detect a source in order to suppress the unwanted electromagnetic wave (electromagnetic disturbing wave) which is the cause of the electromagnetic interference.
Exemplified as conventional techniques concerning the method for detection of an electromagnetic wave source are “A Proposal for Searching for Electromagnetic Wave Sources by Using a Synthetic Aperture Technique” by Junichi Kikuchi et al, Transactions of the Institute of Electronic Information and Communication Engineers of Japan, B-II, October 1985 (prior art 1), “Search for Electromagnetic Wave Sources by Using Maximum Entropy Method” by Junichi Kikuchi et al, Transactions of the Institute of Electronic Information and Communication Engineers of Japan, B-II, September 1986 (prior art 2), “Electromagnetic Field Measurement and Numerical Analysis for EMC Problems” by Sho-se Hayashi, NEC Techniques, September 1993 (prior art 3) and JP-A-4-329376 (prior art 4).
In the prior art 1, minute mono-pole antennas serving as electric field probes are arrayed along a Cartesian coordinate system on a plane at intervals of about ¼ of the wavelength to obtain a result equivalent to the measurement of an unwanted electromagnetic wave using an aperture-front antenna equal to the array area. A position on the aperture front where an electromagnetic wave source exist is identified from a phase shift of the measured value and the operation time can be shorter than that in other techniques and values of both the magnitude and phase can be detected, but there arises a problem that the resolution is rough, amounting up to about ¼ of the wavelength.
In the prior art 2, the maximum entropy method is applied to time-series information of electromagnetic wave measured continuously for a constant time to provide a power spectrum which in turn is made to correspond to the position of an electromagnetic wave source in two-dimensional space. While the positional accuracy is high to advantage, there arise problems that measurement must continue for the constant time or more, phase information of the source cannot be detected and a remote field cannot be determined through calculation.
In the prior art 3, an electromagnetic wave source area is divided into minute gratings, simultaneous equations of current and magnetic field are set up by using the same number of measuring values as that of grating points and the equations are solved to identify the electromagnetic wave source position. Given that the electromagnetic wave source exists on the minute grating and the measuring value is stringently correct, the position can be obtained in the form of a point and true values of the magnitude and phase can be obtained. But, if at least one of the factors contains an error, then there will arise problems that the simultaneous equations do not converge and any solution cannot be obtained or quite an erroneous solution is calculated.
In the prior art 4, an electromagnetic field radiated from an electromagnetic radiation source is measured by a stationary reference antenna and a movable measuring antenna, the amplitude of an electromagnetic field received by the measuring antenna and the phase difference between electromagnetic fields measured by the reference antenna and measuring antenna are used to provide a presumptive expression concerning distribution of electromagnetic disturbing sources and the position of an electromagnetic disturbing source is presumed by a spatial differential value of the presumptive expression. Accordingly, there arises a problem that unless the number of measuring points measured by the measuring antenna is considerably large, a point where the spatial differential value becomes large cannot be found and the accuracy of presumption is degraded.
The present invention contemplates solving the above problems and an object of the present invention is to provide electromagnetic wave sources detecting apparatus and method which can detect and identify a source of unwanted electromagnetic wave (electromagnetic disturbing wave) existing at an arbitrary position on an object to be measured with high accuracy and at a high rate by using a relatively small number of measuring points for the purpose of suppressing the electromagnetic field at a remote location from the apparatus.
Another object of the invention is to provide electromagnetic wave source analyzing system and method which can analyze and decide whether the measured object satisfies the VCCI standards.
Still another object of the invention is to provide electromagnetic wave source analyzing system and method which can survey factors of a source of unwanted electromagnetic wave (electromagnetic disturbing wave) detected on the measured object.
SUMMARY OF THE INVENTION
To accomplish the above objects, an electromagnetic wave source detecting apparatus according to the invention comprises a plurality of probes for measuring intensities Hm (inclusive of phase data) of an electromagnetic field generated from an object to be measured of an electronic apparatus at each measuring position (x
m
, y
m
) which changes two-dimensionally along a measured object plane near the measured object, and calculation means for calculating a phase difference &Dgr;&phgr;
m
=(&phgr;
2
−&phgr;
1
)
m
or time difference &Dgr;t
m
=(t
2
−t
1
)
m
between magnetic fields associated with the probes from the electromagnetic field intensities Hm measured by the individual plural probes at each measuring position (x
m
, y
m
), calculating a difference d between distances from a presumptive electromagnetic wave source on the basis of the phase difference or time difference calculated at each measuring position, determining a locus of the presumptive electromagnetic wave source on the measured object plane from the distance difference d and geometrical relations (for example, z
1
, z
2
) of the plurality of probes to the measured object and detecting an intersection of loci of the presumptive electromagnetic wave source which are determined at a plurality of measuring positions to calculate and identify a position (x
s
, y
s
)
n
of an electromagnetic wave source existing in the measured object.
Further, an electromagnetic wave source detecting apparatus according to the invention comprises a plurality of probes for measuring intensities Hm (inclusive of phase data) of an electromagnetic field generated from an object to be measured of an electronic apparatus at each measuring position (x
m
, y
m
) which changes two-dimensionally along a measured object plane near the measured object, and calculation means for calculating a phase difference &Dgr;&phgr;
m
=(&phgr;
2
−&phgr;
1
)
m
or time difference &Dgr;t
m
=(t
2
−t
1
)
m
between magnetic fields associated with the probes from the electromagnetic field intensities Hm measured by the individual plural probes at each measuring position (x
m
, y
m
), calculating a difference d between distances from a presumptive electromagnetic wave source on the basis of the phase difference or time difference calculated at each measuring position, determining a locus of the presumptive electromagnetic wave source on the measured object plane from th
Shinbo Kenichi
Uesaka Kouichi
Antonelli Terry Stout & Kraus LLP
Hitachi , Ltd.
Nguyen Trung Q.
Sherry Michael J.
LandOfFree
Apparatus and method for detecting electromagnetic wave... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus and method for detecting electromagnetic wave..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus and method for detecting electromagnetic wave... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2904468