Magnetic Field Probe MMP500

  • photo:Magnetic Field Probe MMP500

    Magnetic Field Probe MMP500

    • Conducted disturbance noise measurement up to 9kHz low frequency
    • Optimum for measuring power electronics equipment.

The LISN (Line Impedance Stabilization Network) is used for conducted disturbance noise test.

However, the magnetic field probe MMP500 was born based on the desire to perform this test more easily or to identify the noise source.

This conducted disturbance noise can be easily measured with MMP500 and signal analyzer MSA538E/MSA558E.

MMP500 was completed through joint development with the Tokyo Metropolitan Industrial Technology Research Institute.


  1. Optimum for measuring power electronics equipment.
  2. Using this measurement system, it is possible to measure the conducted disturbance noise of the power supply line without electrical contact and without using LISN. In addition, the disturbance noise on PCB can be measured without contact. Optimum for measuring power electronics equipment used in such as automotive industry.

  3. Precompliance conducted disturbance noise measurement
    • If this system is used, the problem will be solved in the laboratory or outdoors.Save time and money.
    • The signal analyzer MSA538E/558E can operate on battery (4 hours operating time ), so no AC power supply is required.
    • The formal test may be performed once with the official test system (LISN) at the end.
  4. Simple system
  5. The conducted disturbance noise can be measured by a simple system with only the magnetic field probe MMP500 and signal analyzer.


  6. Compatible with various currents 
  7. This probe can handle large current of DC and AC.

  8. Three detection modes
  9. This measurement system has three detection modes of PosPK (positive peak), QP (quasi-peak) and AV (average).

Measurement of conducted disturbance noise

The following is an example of measuring conducted disturbance noise of a power supply line as a DUT (Device Under Test).

Measure placing the probe as perpendicular to the power supply line as possible, aligning the marker of the probe with the power supply line and making contact with the power supply line.

It affects the rotation sensitivity and distance sensitivity described on the following.

In this measurement example, the sheath’s thickness of the power supply line affects the distance sensitivity.

Assuming that the thickness of sheath is 0.5 mm, the disturbance noise is measured as 1.25dB lower because the distance sensitivity is 2.5dB/mm.


  • REF:
    Reference level. By lowering REF, the difference between the average noise level and the limit value can be increased.
  • RBW:
    Resolution bandwidth.
  • VBW:
    Video bandwidth. By using VBW, the average noise level is lowered, and the measurement dynamic range is expanded.
  • MaxHold:
    Max Hold function. By using MaxHold, the noise that occurs intermittently can be captured.

【Fig.1】Full measurement range 〔PosPK detection〕

  • Grasp the noise generation situation in the full measurement range.
    Setting items Setting value
    REF 110dBμV
    RBW 120kHz
    VBW 10kHz
    MaxHold 32 times
  • 図1

【Fig.2】962kHz noise 〔AV detection〕

  • Measure the AV detection value of 962kHz noise that exceeds the limit line at PosPK.
    Setting items Setting value
    REF 90dBμV
    RBW 9kHz
    VBW 1kHz
    MaxHold off
  • 図1

【図3】70.7MHzノイズ [QP検波]

  • PosPKで限度値を超えた70.7MHzノイズのQP検波値を測定します。
    Setting items Setting value
    REF 90dBμV
    RBW 120kHz
    VBW 10kHz
    MaxHold off
  • 図1

[Example of standard value]

Frequency Limit value RBW
9 to 50kHz 110dBμV 300Hz(6dB)
50 to 150kHz 90 to 80 dBμV
150 to 500kHz 66 to 56 dBμV 9kHz(6dB)
0.5 to 5MHz 56 dBμV
5 to 30MHz 60 dBμV
30 to 100MHz 64 to 54 dBμV 120kHz(6dB)

Rotation sensitivity

The marker position of the probe shows 0°.
An error of approx. ± 1dB occurs in the range of 0 to ± 30°.


Distance sensitivity

As the probe moves away from the power supply line, the level of the disturbing noise decreases.
"approx. 2.5dB/mm@1 to 2mm, approx. 6.8dB@3mm and approx. 8.5dB@4mm".


Level calibration method

The level is calibrated by the 50Ω microstrip line method.
The level is measured aligning the marker of magnetic field probe with the 50Ω microstrip line and contacting with it. 

  • Level calibration points: 10 points (linear interpolation is performed at frequencies other than the calibration points)
  • Two kinds of calibration coefficients
  1. Typical calibration coefficient
    Typical values of calibration coefficient are installed in the signal analyzer MSA538E/558E. Usually, the measurement can be done using this values (select "MMP500").
  2. Calibration coefficient attached to MMP500
    Input the calibration coefficient attached to MMP500 from the PC using the command, and install it in “USER B” of MSA538E/558E. When using this, select "USER B". More accurate measurements will be done.

The frequency characteristics of the MMP500 are calibrated in the signal analyzer MSA538E/558E, so that the correct measurement values can be observed on the screen.

*When using a spectrum analyzer other than MSA538E/558E, calibrate the measured level based on the attached calibration coefficient data.

How to use signal analyzer

  1. Selection of measurement with MMP500

    Select “Magnetic field measurement with MMP500” using MSA538E/558E function keys.

    • MEAS:Measuring function
    • MFS:Magnetic field strength measurement
    • PROBE :Probe selection
    • CP-2SA: 10MHz-3GHz magnetic field probe
    • MMP500 :9kHz-100MHz magnetic field probe
    • USER:Calibration coefficient of CP-2SA
    • USER B:Calibration coefficient of MMP500
  2. If the limit line of the standard is close to the average noise level, set to a lower REF.


Frequency range 9kHz to 100MHz (20kHz to 100MHz@MSA538E/558E)
Maximum measurement level 117dBμV
Analysis and display equipment MSA538E and MSA558E

■Detection method
PosPK(Positive peak), QP(Quasi-peak), AV(Average) detection

■Resolution bandwidth
300Hz(3dB) @9 to 150kHz
9kHz(6dB) @0.15 to 30MHz
120kHz(6dB) @30 to 100MHz

■QP detection time constant

RBW 300Hz 9kHz 120kHz
Time constant
Charge 1ms 1ms
Discharge 160ms 550ms


RBW = 300Hz:3dB bandwidth and PosPK (positive peak) only

Level calibration method 50Ω microstrip line method
Rotation sensitivity Deviation from 0° (marker position)
approx. ±1.2dB@0 to ±30°
Distance sensitivity Attenuation by distance from microstrip line (detector surface reference)
approx. 2.5dB/mm@1 to 2mm, approx. 6.8dB@3mm, approx. 8.5dB@4mm
Operating temperature 0 to 50°C (guaranteed at 23 ± 10°C)
Operating humidity less than 40°C/80%RH (guaranteed at less than 33°C/70%RH)
Storage temperature -20 to 50°C
Dimensions 14.5Φ×140mm (probe part) @excluding projections 10.5Φmm (detection portion) Total length:approx.1.2m
Weight approx. 70g (including cable)
Standard accessories Storage case, Adapter MA306, Calibration coefficient data, Operating manual

Storage case

Options ・PC software MAS500
・Logging software MAS510
・PC software for EMI MAS530


PC software MAS500

MAS500 is a software that controls the signal analyzer by the PC and displays the spectrum waveform on PC screen. MMP500 or USER B can be selected in M/F Probe of Measuring function , and the measurement results can be checked on the PC screen and saved.

Logging software MAS510

MAS510 is a logging software that collects the measurement data by uninhabited. It is optimum for watching an abnormal signal at night and recording the data by uninhabited for a long time.

PC software for EMI MAS530

MAS530 is a software used for conducted disturbance noise test. The frequency axis can also be displayed logarithmically. This is used in the "Conducted EMI test system MR2150" described in Related products.

Related products

Magnetic field probe CP-2SA

  • 写真:磁界プローブ CP-2SA

    The magnetic field detection portion of CP-2SA is a shielded loop structure that adopts glass ceramic multi-layer board technology with excellent high frequency characteristics. The magnetic fields of the pattern and the terminal of device on a printed circuit board can be measured. 

    Frequency range 10MHz to 3GHz
    Space resolution approx.0.25mm (depending on objects)
    Dimensions outside:12Φ×135mm
    probe tip:2mm(W)×1mm(T)

LISN (Line impedance stabilization network) MPW201B

  • 写真:ラインインピーダンス安定化回路網(LISN) MPW201B

    ラインインピーダンス安定化回路網(LISN) MPW201B

    When measuring the conducted disturbance noise discharged through the power supply line of EUT, the LISN is used to make constant the impedance of the power source observed from EUT side and to do measurement with reproducibility.
    Frequency range 150kHz to 30MHz
    Circuit type 50Ω/50μH and V type based on CISPR16-1
    Rated current 15A
    Power supply Single phase, 50/60Hz, 250VACmax
    Applicable models MSA438E/538E/558E

Conducted EMI test system MR2150

  • 写真:伝導性EMI試験システムMR2150


    MR2150 is a pre-compliance test system for conducted EMI. The development cost can be significantly reduced by debugging and evaluating EUT using this system before testing in the formal EMC site.


  • Products Catalog
  • How to use Magnetic Field Probe MMP500

*MICRONIX Corporation reserves the right to make changes in design, specification and other information without prior notice.

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