Bidimensional electromagnetic emission level monitoring equipment

• US 5,300,879 A
• Filed: 06/18/1991
• Issued: 04/05/1994
• Est. Priority Date: 06/18/1990
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Inomata, Masayuki, Hatakeyama, Ken-Ichi, Fujihara, Noboru, Harada, Takashi, Masuda, Norio
• Primary Examiner(s): NGUYEN, VINH P
• Application Number:
  US07/717,087
• Time in Patent Office: 1,022 Days
• Field of Search: 324/95, 324/77 D, 324/239, 324/240, 324/242, 324/244, 324/158 R, 343/703, 219/10.55 M, 219/10.55 D, 340/600
• US Class Current: 324/95
• 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

Abstract

Bidimensional electromagnetic emission level monitoring equipment for detecting the electric fields or the magnetic fields of RF (Radio Frequency) emissions from equipment under test by moving an electromagnetic probe bidimensionally. The measuring frequency, the scanning range of the probe, and the distance between measuring points are entered on a keyboard of a controller. A spectrum analyzer selectively receives RF emissions of a designated frequency from the probe in response to an instruction from the controller and feeds emission level signal data to the controller as digital signals. A probe scanning section loaded with the probe is moved bidimensionally by a motor driver under the control of the controller. The controller delivers to a display an emission level distribution signal representative of an electromagnetic distribution based on the emission level data and position data associated with the probe.

Claims

1. Bidimensional electromagnetic emission level monitoring equipment comprising:

an electromagnetic probe for detecting electromagnetic fields;

selective receiving means for separating components having a designated frequency from said fields and generating emission level signals representative of emission levels of said fields having said designated frequency;

outputting means associated with said selective receiving means for outputting emission level signal data corresponding to said emission level signals;

a probe scanning section for carrying said electromagnetic probe thereon and for moving said electromagnetic probe in bidimensional directions in a bidimensional plane;

inputting means for inputting scanning parameters designating a measuring frequency of said fields to be measured and effective for measuring points where said electromagnetic probe should detect said fields;

controller means for supplying to said selective receiving means a frequency corresponding to said measuring frequency entered on said inputting means as said designated frequency;

means for generating position data representative of said measuring points on the basis of said scanning parameters entered on said inputting means and for feeding to said probe scanning section a scanning control signal produced by converting said position data to a displacement of said electromagnetic probe; and

means for generating electromagnetic emission level data by calculating electromagnetic emission levels in response to said emission level signal data and outputting said electromagnetic emission level data together with said position data as an emission level distribution signal representative of an electromagnetic emission level distribution;

wherein said probe scanning section comprises;

a base in the form of a plate for supporting said probe scanning section;

a plurality of first guidance bars extending vertically from and affixed to opposite end portions of said base at one end thereof;

a cross bar provided between and perpendicular to said plurality of first guidance bars and slidable with opposite ends thereof guided by said first guidance bars;

a first stepping motor to which a shift signal from a motor driver is applied for causing said cross bar to slide;

a first drive transmission mechanism for converting a rotary motion of said first stepping motor to a linear motion for driving said cross bar;

a second guidance bar extending between opposite ends of said cross bar;

a probe holder for holding said electromagnetic probe and for sliding on said cross bar while being guided by said second guidance bar;

a second stepping motor to which said shift signal from said motor driver is applied for causing said probe holder to slide; and

a second drive transmission mechanism for converting a rotary motion of said second stepping motor to a linear motion for driving said probe holder.

2. Equipment as claimed in claim 1, further comprising a top plate affixed to the other end of said plurality of first guidance bars and extending parallel to said base.

3. Equipment as claimed in claim 1, wherein said first drive transmission mechanism comprises:

pulleys each affixed to opposite end portions of said plurality of first guidance bars, the rotary motion of said first stepping motor being transmitted to one of said pulleys by a worn gear; and

a belt passing over two of said pulleys and affixed to opposite end portions of said first guidance bars, and affixed at one point to said cross bar.

4. Equipment as claimed in claim 3, wherein said pulleys and said belt mesh with each other with gear teeth.

5. Equipment as claimed in claim 3, wherein at least one of said pulleys located at corresponding positions in the opposite end portions of said base is interconnected by a shaft.

6. Equipment as claimed in claim 1, further including;

pulleys affixed to opposite end portions of said second guidance bar, the rotary motion of said second stepping motor being applied to one of said pulleys; and

a belt passing over said pulleys and affixed to the opposite ends of said second guidance bar, and affixed at one end to said probe holder.

7. Equipment as claimed in claim 1, wherein said probe scanning section is made of a non-magnetic material except for said base and said first and second stepping motors.

8. Equipment as claimed in claim 5, wherein said probe scanning section is made of a non-magnetic material except for said base, said first and second stepping motors, and said shaft.