The highest DC bias of PR-01 should not exceed 50Vdc. It is recommended to test after the power supply of the DUT is connected and stabilized.

When users use the function of EMC Pretest > AC Voltage Probe, the Pre-amplifier preset is turned off. PR-01 is mainly used to measure the EMI signal of the AC power supply.  A large signal feedback during the low frequency measurement is likely to occur that will damage the RF end of the GSP-9330. Therefore, when using the function of the AC Voltage Probe, the preamplifier is preset off. Users can still turn on the amplifier according to the requirements of the measurement.

The characteristics of the PR-01 are listed below. Users can also find the relevant specifications in the GKT-008 user manual.

The measurement result of Debug Mode is not processed.

The Debug Mode is the default mode, and the measurement results are not processed, and the Pretest Mode is the mode after adding the Correction Factor of the PR-01 AC Probe.

The SMA Cable model in the GKT-008 is GTL-303 and its specifications are:

• Insertion Loss: Less than 1.5dB, 0 ~ 3GHz.
• Return Loss: Less than -18dB, 0 ~ 3GHz.

Because the principle of the near field probe is not the same as the working principle of the antenna, there is no antenna factor parameter.

The function of the antenna is to convert the electric field strength ES of the received electromagnetic wave into a voltage , which is measured and displayed by the output port connected to the spectrum analyzer, and the relationship with the antenna factor  is as follows:

is the electric field strength of the signal,is the voltage generated at the output port of the antenna.

In a linear representation,

But in the logarithmic expression,

Therefore, the electric field strength of the electromagnetic wave is equal to the measured reading value (voltage, dBuV) of the spectrum analyzer plus the antenna factor (dB/m). For example, a spectrum analyzer connected to a Biconical antenna has a signal of 30dBuV at 320MHz and an antenna factor of 28dB/m, then the electric field strength is 30dBuV+28dB/m =58dBuV/m.

In the case of the far field of the electromagnetic field described above, the electric field strength Es transmitted in the air is related to the wave impedance Z, which is defined as Z = E / H (the electric field E divided by the magnetic field H). The wave impedance Z of the far field is a constant 377 (120pi) Ohm, which represents that the relationship between the measured value of the electric field and the magnetic field is fixed. The antenna factor can be utilized here.

However, the wave impedance Z of the EMI probe in the near field is not fixed. It is related to the radiation source, the test distance and the probe form. Unlike the fixed far field of 377 ohm, the near field probe does not have the antenna factor.

Using the near field electric field probe and the magnetic field probe to measure the near field electric field and the magnetic field respectively can only obtain the two components of the electromagnetic energy in the EMI signal. The GKT-008 can directly and effectively sense the actual electromagnetic energy.

The near field electric field probe and the magnetic field probe can only measure two components of the electromagnetic energy of the EMI signal. The actual electromagnetic energy is the vector outer product of the electric field and the magnetic field. Hence, the large near field magnetic field does not mean that it will radiate to become the interference of EMI. It is the same for the electric field. Therefore, measuring the near field electric field and the magnetic field is only a substitute method when the electromagnetic wave energy cannot be directly measured. Moreover, the electric field E and the magnetic field H respectively measured by the spectrum analyzer are difficult for the calculation of the electromagnetic energy vector by using the formula.

Moreover, in the process of EMI debugging, the problem of a magnetic field or an electric field must be considered to solve whether for isolation mechanism, filter circuit or grounding design of the circuit in terms of techniques and methods for solving the problem. The main method is to measure the frequency and amplitude (energy) of the EMI noise so as to confirm which circuit or component produces the interference signal source. The interference can be improved by suppressing the current (such as series resistance) or voltage (such as parallel bypass capacitor).

Using the near field probe of GKT-008 to directly measure the electromagnetic energy can directly measure the actual near field electromagnetic energy. There is no need to measure the electric field and the magnetic field separately by using GKT-008, which becomes a more efficient tool. In some special applications, separate analysis of the electric and magnetic fields is required such as larger power motor rotation systems.

Spectrum analyzer with an input impedance of 50 W can use the GKT-008 probe. However, the functions related to GKT-008 in the EMC Pretest built in GSP-9330 cannot be used.

In terms of hardware architecture, the GKT-008 is designed to be used with a spectrum analyzer. Spectrum analyzer with 50 Ω input impedance can use the GKT-008 probe.

However, the GKT-008 has some very useful extension functions that must be used in conjunction with the EMC Pretest feature of the GSS-9330 spectrum analyzer. These features include:

1. Far field EMI measurement estimation
2. Estimation of EMI after the chip's pins are added with traces to the PCB
3. Estimation of EMI after the communications interface is connected to the cable
4. After near field probe ANT-04 is connected with TG, simulate signal source for EMS test

The Correction under EMI Test is used to compensate the signal measurement of the antenna when it is horizontally or vertically polarized; the 3m/10m Correction under Sensor Probe is converted into a 3m/10m anechoic chamber after using the signal measured by the ANT-04 probe. Simulation results. The former is the correction of the antenna far-field measurement, and the latter is the test of the near-field probe simulation in the anechoic chamber.

Yes, at this time, the RBW will switch to the EMI bandwidth according to the current frequency bandwidth.

After setting, each Trace will simultaneously scan PK+, QP, and AVG according to the settings.

When the EMI signal is too strong, the GSP-9330 will send a warning message to avoid damage to the spectrum analyzer. It is recommended to connect an attenuator before the input terminal.

To display two self-defined Limit Lines, please use the GSP-9330 dedicated PC software SpectrumShot.

This PC software must be collocated with the NI-VISA driver. Please download it from the NI website.