The importance of a fully non-magnetic tripod in Shielding Effectiveness (SE) measurements

In Shielding Effectiveness (SE) measurements, the reliability of the result does not depend solely on the performance of the instrumentation used, but on the entire measurement system. Every element within the setup can influence the behavior of the electromagnetic field and, consequently, the quality of the data obtained.

Among these elements, the support used for positioning the measurement instrumentation is often underestimated. An unsuitable tripod, especially if it contains metallic components, can introduce alterations in the measurement and compromise the correct evaluation of shielding performance.

Why does metal affect Shielding Effectiveness measurements?

Shielding Effectiveness measurements aim to determine how well a shielding structure, such as a shielded room, a Faraday cage, or an MRI room, can attenuate an electromagnetic field.

During an SE measurement, the environment surrounding the antenna must remain as electromagnetically neutral as possible. The presence of metallic parts near the measurement point can instead modify the field through several phenomena:

• Reflection of the electromagnetic field: metal can alter signal distribution and modify the actual field present during the test
• Unwanted coupling: parasitic currents may be generated, affecting the behavior of the measurement system
• Result alteration: the measured value may include the effect of the support and not exclusively represent the shielding performance

In other words, an apparently secondary component can become an uncontrolled variable within the setup, compromising the validity of the result.

What errors can a non-non-magnetic tripod introduce?

The use of a standard tripod, such as those typically used in photography or general applications, can introduce errors that are difficult to identify, as they are not always immediately attributable to the support.

A tripod containing metallic parts may cause:

• false leakage points, making the shielding appear less effective than its actual performance
• result variations even with small changes in the support position
• reduced measurement repeatability, making it more difficult to compare results obtained under different conditions

When the measured data is not consistent, the cause is not always the measuring instrument: often, it is the overall setup that determines the quality of the result.

How to choose an antenna support for EMC measurements?

To ensure reliable and repeatable Shielding Effectiveness measurements, the antenna support must be designed for EMC and RF applications, meeting specific construction requirements.

A suitable tripod must be:

• completely non-magnetic
• free from any metallic components, including screws, joints, or internal parts
• made of non-conductive materials, such as fiberglass or equivalent materials

These characteristics help minimize the interaction between the support and the electromagnetic field, keeping measurement conditions as close as possible to those defined by test procedures.

Why is a non-magnetic tripod important for compliance with SE standards?

Shielding Effectiveness measurements are typically performed according to procedures defined by standards such as IEEE Std 299 and MIL-STD-285, where proper setup configuration is essential to obtaining reliable results.

Using a fully non-magnetic tripod helps ensure that the measurement result reflects the actual shielding capability of the tested structure, rather than effects introduced by the support system.

Why is every detail of the setup important in Shielding Effectiveness measurements?

In EMC and RF measurements, every component present in the test area can influence the final result. The tripod should not be considered a simple accessory, but an integral part of the measurement system.

Choosing a fully non-magnetic and metal-free support ensures greater accuracy, reliability, and repeatability, reducing the risk of misinterpreting data.

A correct measurement does not depend only on the instrument used: often, it is the quality of the setup that determines the quality of the result.