RadiMation Application Note 162

How to perform a MIL-STD-461 RE103, radiated emissions, antenna spurious and harmonic outputs test

This application note explains how the MIL-STD-461 RE103, radiated emissions, antenna spurious and harmonic outputs test can be performed with RadiMation^®.

The "RE103, radiated emissions, antenna spurious and harmonic outputs" test applies as an alternative to CE106 for testing transmitters with their intended antennas, ensuring emissions do not exceed RE102 limits in transmit mode. It is preferred for systems with active antennas or non-standard impedance curves. It applies from 10 kHz to 40 GHz, excluding the signal bandwidth and ±5% of the fundamental frequency, with larger exclusions for high-power Navy shipboard systems.

The exact requirements and test methods for the RE103 are specified in the MIL-STD-461.

Necessary equipment

The following devices should be configured:

• Measurement receiver
• Band rejection network
• Attenuators / filters
• Antenna

Correction files

Calculate the correction value for the far field

For the correct calculation of the ERP value the distance (R) is determined. See section 5.19.3.4a for details.
In this example a transmitter dipole antenna for 2.4 GHz is used which is smaller than the receive antenna. In this case we can use the following formula to calculate the far field distance $R={\frac {2D^{2}}{\lambda }}$ where:

• $D$ is the diameter of the antenna.
• $\lambda$ is the wavelength.

R = 6.25 cm = 0.0625 meters

To calculate the value for the correction file use the following formula: $20\log R$ The outcome of this formula should be used in a correction file.

In this case the value to correct for is: ${\displaystyle 20\log(0.0625)=-40{\text{$dB}}}

Create a correction file for the far field correction value:

    File

       New

          Correction

First create a correction file in RadiMation^® and specify the value of -40 for the applicable frequency range.

Save the correction file on disk and attach it to cable driver that will be used in the test equipment.

EUT Testing

EUT Testing equipment

The configuration of the eut testing test site should contain the following devices:

#	Device name	Tab in test site configuration window	note
	Antenna	Devices 1	The receiving antenna to use
	Spectrum analyser	Devices 2	The measurement receiver or spectrum analyser to use
Cables
①	Cable preamp-> analyser	Cables	Cable with a correction file specified for the band rejection filter or high pass filter
②	Cable preamp-> analyser	Cables	Cable with the specified loss of the used attenuator
③	Cable preamp-> analyser	Cables	Cable with a correction file specified for cable loss

Configure the EUT test

To perform the eut test, create a radiated emissions multiband test. The radiated emission multiband test, can be started by selecting from the menu:

    Tests

       Radiated Emission

          Multiband

Start

The start frequency of the test. For example 1 MHz.

Stop	The stop frequency of the test. For example 20 GHz.

Reference Level

The reference level set in the analyser. This setting is not used when a receiver is used.

Attenuation

The attenuation set in the receiver.

RBW	The RBW set in the receiver.

Step size

The step size set in the receiver.

Measure time

The measure time set in the receiver.

Preamplifier

The preamplifier setting set in the receiver.

Traces

The type of trace set in the receiver. For MIL-STD-461 RE103 the peak detector is used.

Test Equipment

The equipment used for the measurement.

Location type

The type of measurement that should be used. Set this to Antenna spurious and harmonic outputs.

Max Height

The maximum height for the antenna tower.

Min Height

The minimal height for the antenna tower.

Steps

The number of height positions to measure.

Move during measurement

If the antenna tower can move during the measurement.

Optimize Height

Find the optimal emission around a certain height. This is normally not used during MIL-STD-461 RE103 measurements, and can thus be unchecked.

Distance

The distance between the antenna and the EUT. The antenna distance determined in 5.19.3.4a.

Antenna Polarization

Which polarization is used, Vertical, Horizontal or Both.

Start Angle

The minimal turn table angle.

End Angle

The maximum turn table angle.

Steps

The number of angles to measure.

Turn during measurement

If the turn table can move during the measurement. This is normally not used during MIL-STD-461 RE103 measurements, and can thus be unchecked.

Optimize Angle

Find the optimal emission around a certain angle. This is normally not used during MIL-STD-461 RE103 measurements, and can thus be unchecked.

EUT Angle Offset

The offset of the EUT on the table. This is normally not used during MIL-STD-461 RE103 measurements, and can thus be set to 0 degrees.

Limit Lines

The applicable limit line can be added, in this example the "MIL-STD-461 RE102 XXX-XXX" limit line file.

All peaks above x dB below the limit line

Which level above x dB below the limit line the peaks should be detected.

Peak detection

How many peaks should be detected automatically. For a MIL-STD-461 RE103 peaks will be selected manually

Final peak measurement

It is possible to perform a final measurement on a peak with the selected detectors. Normally no final measurement is needed for the MIL-STD-461 RE103 measurement, and all detectors can thus be unselected.

Effectively Radiated Power

Decibel

Equipment Under Test

Resolution BandWidth