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FAQ

What is the difference between RF shielding and EMI shielding? 

In everyday use, the terms are often used interchangeably. RF shielding generally refers to blocking higher-frequency wireless signals such as cellular and Wi‑Fi, while EMI shielding is a broader concept that covers a wider range of electromagnetic interference sources. In most residential applications, both types of protection are considered together.

Why would someone install a shielded room in a home? 

There are several common reasons, including reducing unwanted external RF signals, creating a more controlled environment for sensitive equipment, enhancing privacy by limiting signal leakage, setting up a secure workspace, improving sleep conditions in a low-interference environment, or even supporting specialized uses such as safe rooms or bunker-style builds.

Does RF shielding block Wi‑Fi, cellular, and Bluetooth? 

Yes. When properly designed and installed, a shielded room can significantly reduce or fully block wireless signals such as Wi‑Fi, cellular, Bluetooth, and GPS. The actual level of attenuation depends on factors like design specifications, door and seam quality, and the frequency range being targeted.
Which EMR measuring device is right for you, and how should you begin?
Before investing in any shielding materials, it’s important to first evaluate your environment for both EMF and RF radiation. For the most reliable assessment, we recommend using two separate devices: one specifically designed for EMF measurements and another dedicated to RF detection.
You can also find kits that combine both types of meters for added convenience, with options listed here.
Ultimately, the best choice of meter depends on the level of precision you require when identifying RF and EMF sources. In general, higher-end models provide greater sensitivity—allowing them to detect both very low and very high readings—as well as broader frequency ranges for more comprehensive coverage.
If you’re looking for more answers to common EMF FAQs, you can click here to book a free consultation with our EMF experts.

Which shielding material is best for me?

It often depends on the application, practicality in your environment, and budget. Viewing the product specification sheets will help to inform what types of applications may be best, and what range of frequencies are shielded.

Do I need to ground shielding materials?

Grounding of shielding materials is done to reduce nearby AC electric fields. It is also strongly recommended to prevent any chance of electrical shock, in the rare chance a live wire makes contact with the material. For example, this can happen if drilling into the wall, and accidentally striking a live wire. Grounding is recommended if the shielding material is applied to surfaces that have live wiring running behind.

What are sources of AC electromagnetic fields?

More information may be found here.

What are sources of radio frequency/microwave radiation?

More information may be found here.

What are sources of dirty electricity / MEP?

Common sources include:

  • dimmer switches
  • compact fluorescent lamps (CFLs), dimmable LEDs and halogen lights
  • Switched mode power supplies (e.g. AC-to-DC adapters for many devices)
  • Variable speed motors (e.g. energy-efficient appliances, front load washing machines)
  • Solar and inverter charging systems

I installed RF shielding material and I do not feel/see a change or I feel worse. Why?

  • Please be aware a total enclosure of RF shielding material is often required to achieve the maximum reduction listed on the product specification sheets. Assuming all interior and local RF sources have been addressed and/or eliminated, this may require mitigation materials on other areas (e.g. ceilings, walls, floors, doorways) for exterior RF sources.
  • If you have only shielded one or two surfaces, it is possible RF can be entering from the other side of the measuring space, including floors and ceilings.
  • Sometimes, the RF analyzer may not be sensitive enough to measure the new results (i.e. detecting and registering lower measurement values).
  • If available, using the sound signature analysis feature on an RF analyzer can assist in identifying RF sources.

I installed RF shielding material and still have bars on my cellphone, why?

It is very difficult to quantify RF with bars on a cellphone. All modern cellphones have the ability to adjust their power output in order to compensate for a weak signal, or to conserve battery in a strong signal environment. As you put a cell phone under a shielded enclosure, it recognizes it is not getting a signal any more so it boosts its power output in order to get one.  The phone may still show a bar or two because it is transmitting very hard to compensate for the weak signal present.  This is why an RF Meter is required, as it can accurately quantify the different levels inside the canopy vs outside the canopy. 

RF shielding material is best used at a distance that addresses far-field radiation (i.e. approximately 3 wavelengths away from RF source). Having the shielding material closer than this distance often only addresses near-field RF radiation. This may require finding out the operating frequency of the RF source, in order to find the wavelength.

Can I cover my router with Swiss Shield fabric to block RF radiation?

Please be aware the fabric may not perform to specification by covering a device such as a router. This is because the fabric is designed to be used against far-field radiation. By covering the router (i.e. having the fabric so close), it would only cover near-field radiation. If you decide you still want to cover your router with fabric for your own experimentation purposes, a fabric such as the Swiss Shield Ultima may be considered.

With routers, there are other variables to consider other than the router itself, such as other RF-emitting devices connected to it (e.g. laptop, phones). Same can be said for laptops and all the wireless devices used with it (e.g. wireless mouse, keyboards).

What are considered exposure safe levels?

More information may be found here.

How can I detect / measure 5G?

Most RF meters offered by SLT can measure the low-frequency band (~ 600 - 700 MHz) and mid-frequency band (~ 2.5 - 6 GHz) of 5G technology. Make sure the RF meter has a frequency range that covers these frequencies. Currently, SLT is not yet aware of a consumer-level product that is capable of detecting wireless RF in the 5G high-frequency band (~ 24 - 60 GHz).

How can I shield from 5G?

Generally, standard RF shielding materials (e.g. Yshield paint, RF Foil) may be used. Please note SLT does not yet have test data available in the frequency ranges of 24 GHz and above for products such as the fabrics, mesh, and window films.

Does RF shielding material reflect or absorb frequencies?

RF shielding materials are designed to reflect emissions from RF sources.

My Radio Frequency meter is showing a high reading, but I do not have any wireless sources around me?

It is important to address possibly unknown interior and local RF sources. There is still a possibility of exterior sources influencing the readings (e.g. cell tower, neighbor’s wireless sources).

Can I wear Swiss Shield fabrics as clothing?

SLT does not have specific recommendations for garments, since we have had mixed feedback on the application. The Swiss Shield fabrics work well for RF shielding. Although most of the Swiss Shield fabrics are considered non-conductive, the fabric does have metalized threads, so there is still the possibility of low-frequency AC electric field coupling if the fabric is close enough to your body. Generally, the greater the distance between yourself and the fabric, the better.

SLT normally recommends to focus efforts on areas in the home where you may spend the most time - especially the bedroom - before looking into portable options.


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