Apparatus and method for detecting electromagnetic wave source, and method for analyzing the same

• US 6,411,104 B1
• Filed: 04/20/2000
• Issued: 06/25/2002
• Est. Priority Date: 04/23/1999
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Shinbo, Kenichi, Uesaka, Kouichi
• Primary Examiner(s): Sherry, Michael J.
• Assistant Examiner(s): Nguyen, Trung Q.
• Application Number:
  US09/553,319
• Time in Patent Office: 796 Days
• Field of Search: 324/72.5, 324/95, 324/360, 324/615, 324/633, 324/240, 324/244, 324/242, 324/239, 324/158.1, 324/703, 340/600
• US Class Current: 324/633
• CPC Class Codes: G01R 29/0814 Field measurements related to measuring influence on or from apparatus, components or humans EMC, EMI and similar testing in general G01R31/001, e.g. in ESD, EMI, EMC, EMP testing, measuring radiation leakage; detecting presence of micro- or radiowave emitters; dosimetry; testing shielding; measurements related to lightning
• CPC Class Codes: G01R 29/0821 rooms and test sites therefor, e.g. anechoic chambers, open field sites or TEM cells for testing antennas G01R29/105

Abstract

There are provided electromagnetic wave source detecting apparatus and method as well as electromagnetic wave source analyzing system and method which can detect and analyze a source of (electromagnetic disturbing wave) representing a main factor in generating an electromagnetic field remotely of the apparatus in order to suppress the electromagnetic field intensity at the remote distance from the apparatus to below a regulated value. In the present invention, a magnetic field near an object 110 to be measured is measured by a set of at least two or more probes 101 and 102, a position of an electromagnetic wave source is detected through simplified calculation of one function using a phase difference between the two probes, a current distribution on the measured object is determined by solving simultaneous equations containing the position information and magnitudes of measured magnetic fields and an electromagnetic field at a remote distance from the apparatus is determined from the current distribution, thereby identifying the source representing the main factor in generating the electromagnetic field remotely of the apparatus.

Claims

1. An electromagnetic wave source detecting apparatus comprising:

a plurality of probes for measuring intensities of an electromagnetic field generated from an object to be measured of an electronic apparatus at each measuring position; and

calculation means for calculating a phase difference or time difference between magnetic fields associated with said probes from the electromagnetic field intensities measured by the individual plural probes at each measuring position, determining a locus of a presumptive electromagnetic wave source on the measured object plane on the basis of the phase difference or time difference calculated at each measuring position, 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 of an electromagnetic wave source existing in said measured object.

2. An electromagnetic wave source detecting apparatus according to claim 1, wherein said plurality of probes are arranged on the same probe axis at the individual measuring positions.

3. An electromagnetic wave source detecting apparatus according to claim 1, wherein said plurality of probes are arranged on the same probe axis vertical to said measured object plane at the individual measuring positions.

4. An electromagnetic wave source analyzing method comprising collating a position of an electromagnetic wave source existing on a measured object identified by using the electromagnetic wave source detecting apparatus as recited in claim 1 with information as to a mounting state of said measured object.

5. An electromagnetic wave source detecting apparatus comprising:

a plurality of probes for measuring intensities of an electromagnetic field generated from an object to be measured of an electronic apparatus at each position; and

calculation means for calculating a phase difference or time difference between magnetic fields associated with said probes from the electromagnetic field intensities measured by the individual plural probes at each measuring position, determining a locus of a presumptive electromagnetic wave source on the measured object plane on the basis of the phase difference or time difference calculated at each measuring position, 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 of an electromagnetic wave source existing inside said measured object and further calculating magnitude of a current in the electromagnetic wave source existing at the identified position on the basis of the electromagnetic field intensities measured by said probes at each measuring position.

6. An electromagnetic wave source detecting apparatus according to claim 5, wherein said plurality of probes are arranged on the same probe axis at the individual measuring positions.

7. An electromagnetic wave source detecting apparatus according to claim 5, wherein said plurality of probes are arranged on the same probe axis vertical to said measured object plane at the individual measuring positions.

8. An electromagnetic wave source detecting apparatus according to claim 5, wherein said calculation means further calculates inversely an electromagnetic field intensity at a desired remote distance on the basis of the calculated magnitude of a current in the electromagnetic wave source existing at the identified position on said measured object.

9. An electromagnetic wave source analyzing method comprising analyzing whether an electromagnetic field intensity at a desired remote distance calculated by using the electromagnetic wave source detecting apparatus as recited in claim 8 satisfies the VCCI standards.

10. An electromagnetic wave source detecting apparatus comprising:

a plurality of probes for measuring intensities of an electromagnetic field generated from an object to be measured of an electronic apparatus at each measuring position; and

calculation means for calculating a phase difference or time difference between magnetic fields associated with said probes from the electromagnetic field intensities measured by the individual plural probes at each measuring position, determining a locus of a presumptive electromagnetic wave source on the measured object plane on the basis of the phase difference or time difference calculated at each measuring position, 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 of an electromagnetic wave source existing inside said measured object, and further calculating magnitudes of current distribution in a plurality of electromagnetic wave sources existing at individual plural positions identified similarly on the basis of the electromagnetic field intensities measured by said probes at each measuring position.

11. An electromagnetic wave source detecting apparatus according to claim 10, wherein said plurality of probes are arranged on the same probe axis at the individual measuring positions.

12. An electromagnetic wave source detecting apparatus according to claim 10, wherein said plurality of probes are arranged on the same probe axis vertical to said measured object plane at the individual measuring positions.

13. An electromagnetic wave source detecting apparatus according to claim 10, wherein said calculation means further calculates inversely an electromagnetic field intensity at a desired remote distance on the basis of the calculated magnitude of a current distribution in each of the plurality of electromagnetic wave sources existing at each of the identified plural positions on said measured object.

14. An electromagnetic wave source analyzing method comprising analyzing whether an electromagnetic field intensity at a desired remote distance calculated by using the electromagnetic wave source detecting apparatus as recited in claim 13 satisfies the VCCI standards.

15. An electromagnetic wave source detecting method comprising the steps of measuring intensities of an electromagnetic field generated from an object to be measured of an electronic apparatus at each measuring position by using a plurality of probes,

calculating a phase difference or time difference between magnetic fields associated with said probes from the magnetic field intensities measured at each measuring position, determining a locus of a presumptive electromagnetic wave source on the measured object plane on the basis of the phase difference or time difference calculated at each measuring position, 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 of an electromagnetic wave source existing inside said measured object.

16. An electromagnetic wave source detecting method comprising the steps of measuring intensities of an electromagnetic field generated from an object to be measured of an electronic apparatus at each measuring position by using a plurality of probes,

calculating a phase difference or time difference between magnetic fields associated with said probes from the electromagnetic field intensities measured at each measuring position, determining a locus of a presumptive electromagnetic wave source on said measured object plane on the basis of the phase difference or time difference calculated at each measuring position, detecting an intersection of loci of the presumptive electromagnetic wave source which are determined at a plurality of measuring positions to calculate and identify an electromagnetic wave source existing inside said measured object, and further calculating magnitude of a current in the electromagnetic wave source existing at the identified position on the basis of the electromagnetic field intensities measured by said probes at each measuring position.

17. An electromagnetic wave source detecting apparatus comprising:

a plurality of probes for measuring intensities of an electronic field or magnetic field generated from an object to be measured of an electronic apparatus at each measuring position; and

calculating means for calculating a phase difference or time difference between electric fields or magnetic fields associated with said probes from the intensities measured by the individual plural probes, calculating and identifying a position of an electromagnetic wave source existing in said object to be measured by using the phase difference or time difference thus calculated.