Skip to navigation Skip to content

RF Blocking: RF Shields vs. RF Absorbers

Minute Read

Table Of Contents


    Key Points

    • The terms “RF shield” and “RF absorber” are often mixed up, and they are not the same thing.
    • However, they are often used in conjunction with one another.
    • Whether you need one or both manufactured, you need a high-quality, experienced manufacturing partner to help you.

    keypoints-bottom-borderOften, someone who is in the process of designing a part or device knows that they will need to prevent radio frequency (RF) signals from reaching certain parts of the device. They know that RF interference can cause sensitive devices to malfunction or fail, and that’s not something any engineer wants.

    So, they know they need to keep RF signals out. But do they need to do that with an RF shield, RF absorber or both? No matter how similar those two terms may sound to you right now, you need to understand that RF shields and RF absorbers are not the same thing. They both serve similar but distinct functions on and in devices across the spectrum of industries.

    In this post, the Modus Advanced team helps you break down the differences between RF shields and RF absorbers and how both items are used for RF blocking in general. Read on to learn everything you need to know.

    -- Article Continues Below --

    RF Shielding Resource Center

    Read Everything You Need To Know About RF Shielding 

    What Is an RF Shield?

    An RF shield is a device — usually made of metal but sometimes formed from plastic — that is designed with one purpose: RF blocking. It is typically formed to create a shielded enclosure that protects particularly RF-sensitive components within it. Alternatively, an RF shield may be formed around an RF-emitting device to block RF signals from escaping and interfering with nearby electronics.

    Classic examples of RF shields include the Faraday cage (the typical RF shield structure used in consumer kitchen microwaves) and the RF-shielded facilities that house MRI machines. However, the majority of RF shields in technologically advanced industries like defense, aerospace, medical devices and telecommunications are custom-built. In other words, there’s no end to the types of RF shields you may encounter or design for your own devices.

    What Is an RF Absorber?

    Generally, an RF absorber is a much simpler device than an RF shield. RF absorbers are typically formed from magnetic sheet stock and placed on a flat surface of a device much like a sticker.

    Using either magnetic stock material or elastomeric material filled with conductive and ferromagnetic particles, RF absorbers create a sort of electrical field around themselves. When RF signals reach them, they are polarized and remain with the electric field, effectively meaning they have been absorbed.

    RF Absorbers vs. RF Shields

    If you pay close attention to the actual words in the names of these two parts, you can start to truly understand the difference between RF shields and RF absorbers. Think of a shield like a shield on a medieval battlefield — it was meant to shield the user from stabbing swords and swinging axes. Think of an absorber like a sponge — it soaks up any liquid it comes into contact with.

    RF shields and absorbers run parallel to those two comparisons. RF shields block radio frequency interference (RFI) from reaching the enclosed part or components, while RF absorbers literally absorb RFI that reaches them. 

    -- Article Continues Below --


    Read the Case Study: How Signal Hound Overcame 6 Months of Delays

    Both Are Involved in RF Blocking

    If it isn’t already obvious, both RF shields and RF absorbers play a part in protecting devices from RFI. The difference is just in how they accomplish RF blocking. 

    RF shields rely on the properties of their materials and basic shapes to prevent offending signals from entering an enclosure — often by reflecting, redirecting or redistributing them. 

    RF absorbers, on the other hand, rely on the electric field from metal filler particles or the magnetic field from magnetic materials to polarize incoming radiation, which causes it to remain in the electric field of the absorber. This creates the effect of “absorbing” the incoming RF signals.

    They Are Often Used on the Same Devices

    RF shields and RF absorbers are two attempts to solve the same problem: RFI. That’s why they are often used on the same devices. If both do RF blocking but in different ways, in most cases, it can’t hurt to have both present on a sensitive device. In fact, RF absorbers are often applied to RF shields to enhance their RF blocking capabilities.

    Modus Advanced: RF Blocking Done Right

    While some RF absorbers are installed on or in RF shields, they are not the same thing. In the breakdown of RF shields vs. RF absorbers, some key details differentiate these two distinct but essential RF blocking tools. And it’s those kinds of details that can make or break a device’s functionality.

    That’s why it’s essential that not only you and your team understand the difference between RF shields and RF absorbers, but your chosen manufacturing partner understands the difference, too. Everyone needs to be on the same page as it relates to exactly how your device will prevent interference from RF signals. Even a slight miscalculation, manufacturing defect or similar oversight could leave your device dead in the water.

    You can’t have that. And you won’t if you work with Modus Advanced. Our team of engineers and seasoned professionals is dedicated to manufacturing quality and, by extension, your success. To learn more about how we can help you manufacture RF shields and apply RF absorbers, reach out to us by calling 925-960-8700 or contacting us online.


    Submit a design