EMI / EMC probes

The EMC-100A, 100B, and 100C are loop probes which are sensitive to magnetic fields. They have integrated electrostatic shields, providing isolation from common-mode signals. As a result these probes deliver excellent repeatability. The different loop sizes allow the user to select the optimum probe for a given frequency. The smallest loop size has the best high-frequency response and spacial resolution but lower sensitivity. The larger loop has greater sensitivity but lower frequency response and spacial resolution.

The EMC-100D is a stub probe, sensitive to electric fields. With its 0.08" wide tip, this probe offers the highest spatial resolution. It is ideally suited to tasks such as tracking EMC sources down to the individual pins of an IC. It does not provide the common mode rejection of the 100A/B/C magnetic field probes, hence the sensitivity plotted above can change due to the user's grip on the probe or cable.

These probes require a display instrument (not included) such as spectrum analyzer, power meter, or oscilloscope with 50-ohm input impedance and sufficient sensitivity to show the power received from the probe. The probes have practically no minimum measurable field since the resolution will depend on your display instrument. No battery or power supply is needed for the probe. The probes are single-axis so they respond to fields orthogonal to the loop or parallel to the stub.

Features

Integrated electrostatic shield in the loop probes eliminates common-mode pickup.

Multiple loop sizes offer optimum sensitivity and spatial resolution at different frequencies.

Probe dimensions optimized for access to tight spaces.

Calibrated sensitivity up to 3 GHz, depending on model. Usable to beyond 6 GHz.

Can be driven by a signal source to generate fields for electromagnetic susceptibility testing.

Applications

Finding sources of EMC emissions problems.

Radiating susceptible circuits to find pickup points.

Noninvasive probing of RF circuits. The probes can be used to measure the signals present on an operational

PC board. For example, using a preamplifier, the probes can measure the characteristics of an oscillator,

such as frequency, sidebands, and phase noise.

Probe Specifications:

Dimensions:

Length, excluding connector: 6.35" (161 mm)

Tip thickness: 0.11" (2.8 mm)

Tip Diameter: See next to photos above.

Frequency Response and Sensitivity:

The curves above show the measured output power into 50 ohms.

Probe output power can also be computed from the following equations.

Loop Probes (EMC-100A/B/C): This equation is accurate within 3 dB from DC to the 3 dB point indicated in the

table below. The probes are usable at higher frequencies, but the sensitivity is uncalibrated. The first notch in

the frequency response of the probes occurs at the first resonance listed in the table.

Output Power = [X + 20*log10(B) + 20*log10(F)] dBm

Where B is the magnetic flux density in Tesla,

F is the frequency of the received signal in Megahertz

X is a scale factor from the following table:

Loop SizeX3-dB Frequency First Resonance

Large 85.1 50 MHz 500 MHz

Medium 67.1 1000 MHz 2600 MHz

Small 44.4 3100 MHz>6000 MHz

Electric Field Probe (EMC-100D): Stub probes tend to be less repeatable than shielded loop probes, due to the

presence of common-mode currents flowing on the outer surface of the probe or attached cable. As signals are

measured, it is common to see a few dB of variation in output power as the user changes their grip on the probe

or the attached cable. Because of this, the sensitivity of the 100D is not guaranteed. Typical sensitivity of the

Electric Field Probe is given by the following equation and in the 100D figure above.

Output Power = [-113.2 + 20*log10(E) + 20*log10(F)] dBm

Where E is the electric field strength, in Volts/meter

F is the frequency of the received signal in Megahertz

Connector: SMB male, 50 ohms (adapters also available see photos above).

Warranty: 30 day unconditional return policy. 1 year warranty