How is Shielding Tested to Determine Shielding Effectiveness?

Shielding effectiveness testing is a core competency of Keystone Compliance. We have developed a process that allows us to test samples of various sizes. Our capabilities are wide-ranging and we provide guidance from the completion of the test plan to the issuance of the test report.

We have several setups available within our lab. We can accommodate the testing of various materials of different sizes and a complete spectrum of frequencies. Our EMC lab features seven chambers and multiple ground plane and ESD work stations.

If you need professional shielding effectiveness or EMC testing, you have come to the right place. Please contact us to start a conversation and request a quote.

The remainder of this page will address the shielding effectiveness testing process.

No matter the standard for shielding effectiveness, the general procedure for testing shielding effective compliance follows the same process.

First, two antennas are set up on opposite sides of the sample for test. One antenna acts as a transmit antenna. It is connected to a signal generator to sweep through the required frequency range.  The second antenna is a receive antenna. This antenna measures the received field strength. This information is stored in data form. This data represents the signal attenuation, or loss of signal through the barrier.

As a verification of results, there is a step prior step to the actual measurement of the sample under test. This step requires a calculation of the dynamic range such that accurate results are being made. Therefore, two measurements must be made. The first with no barrier. This means there is nothing between the transmitting and receiving antenna.

The second measurement is with a barrier. This is typically a metallic surface that is the best under materials used in shielding. The resulting signal should be the floor level noise of the antenna and receiver with additional safety margin. This is usually 6 dB, to take account for error.

Once these two verification measurements are taken, the dynamic range can be calculated. This is simply the difference between the maximum and minimum signals. The amount of dynamic range must be greater than the amount of desired signal attenuation from the enclosure shielding from the sample.

Otherwise, the unit outperforms the test chamber, and thus concludes the sample shields better than the chamber, which should never be the case. It is important to always verify data, especially if the outcome appears to support this situation.

There are two kinds of measurements that can be taken regarding an electric or magnetic field. The first is a far field electromagnetic wave. The second is a near field electromagnetic field. When considering a far field electromagnetic wave measurement, this is when the electric and magnetic field are orthogonal or perpendicular to each other. The normal, or along with, is the direction of the energy generation.

In the test setup, this would be the signal generator. For the opposite direction, this is just the opposite case. This is where there is no region where the electric and magnetic fields are related at all. In other words, considering the working of an antenna system, the near field is very close to the antenna, and far field means further away.

In addition to determining the shielding of materials, we can also access the shielding of cables. The shielding of cables can reduce the coupling of radio waves, electromagnetic fields and electrostatic fields. The amount of reduction can vary based on several factors.

For instance, the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest can all have an impact. Also impacting the effectiveness of the shielding is the size, shape and orientation or apertures in a shield to an incident electromagnetic field.

Electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as RF Shielding. When purchasing off the shelf products or components, it is always important to review the shielding capabilities of the product.

Ready to determine the performance of your material, cable, product or facility. Regardless of the need, Keystone Compliance is the shielding effectiveness test lab for you. Our accredited engineers provide guidance throughout the test program. We understand the importance of antenna distances and positioning.

Our ISO-17025 accredited lab generate test reports that are recognized throughout the world. Our customers have the confidence of knowing that all of the necessary testing can be completed accurately, timely and affordably in our lab.

Request a Quote to learn firsthand why so many manufacturers partner with Keystone Compliance to meet their shielding effectiveness testing needs.