Sign up today for our weekly newsletter that contains the latest product news and exclusive promotions for our customers. ETS-LINDGREN'S COPPER RF SHIELDING uses both a superior RF attenuator and the durability of bolted, light weight modular panels to ensure reliable performance. ETS-Lindgren is the leader in design-build radio frequency (RF) shielding solutions for MRI systems with over 6,500 successful installations worldwide. In every wireless system, almost every wire becomes an antenna or a receiver, and the spurious signals they inadvertently receive or transmit can degrade the overall performance of the RF subsystem. EMI is basically disruptive electromagnetic energy that is emitted by one portion of the circuit and reaches other portions of the circuit or the external world via conducted or radiated paths. Whether your design is a cell phone, a tablet, a portable computer, or some other portable product, good PCB layout is critical to keeping EMI to a minimum. Emitted radiation, generated by both differential and common-mode currents, propagates along a conducting medium or by radiation through space.
Shorter wavelengths can approach the physical dimensions of many EUTs (Equipment Under Test), which leads to possible cavity resonance effects. Even weak coupling at these extremely high frequencies can induce strong oscillations which can then couple to any other points in the enclosure or the oscillations can radiate. Once the PCB design has been optimized for minimal emissions, the next stage of the design process is to shield critical sections of the board to prevent emissions, or prevent emissions from other portions of the system from affecting sensitive circuits. Shielding can be a stand-alone solution, but it is more cost-effective when used in conjunction with other suppression techniques such as grounding, filtering, and, as mentioned earlier, proper circuit-board design to minimize the loop area.
Pi is the incident power, Pe is exit power, Fi is incident electric magnetic or plane wave field intensity, and Fe is exit electric, magnetic, or plane wave field intensity. Shields can take on many shapes and sizes, and range from simple metal boxes to conductive foams and metal films. The ability of the shielding to block or absorb the RF signals is determined by several factors – the conductivity of the material, the permeability of the material, and the material thickness. However, regardless of the gasket type, key factors to consider when choosing a gasket are RF impedance (R + jX, where R = resistance, jX = inductive reactance), shielding effectiveness, compressibility, compression forces, compression range, compression set, and environmental sealing. Enclosures containing emitters should be designed for maximum absorption loss of the emitted field. Enclosures containing receptors should be designed for maximum reflection loss of the received field. This overview of shielding approaches shows that basic shielding theory is really not so basic. DTi offers the FA Series RF Absorber Materials for the suppression of electromagnetic waves in electronic devices. Shielding box or shielding equipment by metal shielding electromagnetic wave, has excellent electromagnetic wave shielding properties.
Shielding box can be widely used in wireless communication modules, such as Bluetooth, GSM, WCDMA, WLAN, WiMAX, RFID, car remote control, or wireless communications products such as mobile phones, wireless LAN, wireless router, wireless headsets, Bluetooth headsets, data card, walkie-talkie during board test and final test. RF shielding materials are an important consideration when designing electronic components because these materials help ensure that the electronic device will perform to its optimum functionality. This article will discuss factors to consider when selecting RF shielding materials for an electronic device.
This article will provide a sample plan to assist in determining precisely what factors must be considered to reduce the cost of dealing with the mitigation of EMI. The chart in Figure 1 shows that EMI costs can be held to a minimum if they are considered at the beginning of the project.
A comprehensive “EMI Control Plan” should be developed, and it can be organized as detailed below. A carefully executed EMI control plan will show where RF shielding materials will be required.
Electrically conductive elastomers (EcE) that are hollow will reduce material costs as well as compression forces. A cost-effective alternative to standard products is modified standard products, such as shown in Figure 3. Many manufacturing processes used for producing standard products can be altered to produce “modified standard” products. Custom RF shielding products (Figure 4) still play a large role in the design of electronics products. Always fabricate enclosures from the fewest number of pieces and utilize existing metal structures such as the ground layer in the PCB, internal metal divisions, or disk drive base plate as part of the shield. Whenever possible, use a knife-edge or pan-edge panel arrangement for doors and access panels. Shield gaskets should be installed to provide the highest surface conductivity, conductive-to-conductive condition. In all cases, the gasket material should be selected or plated to achieve galvanic compatibility.
Placing larger blanket orders with set release dates will allow the RF shielding manufacturer to plan ahead and will lower the price.
For high volume custom parts, tooling of high-speed progressive dies will reduce piece price.
Set up a safety stock program so that larger orders can be run through in one batch, thereby reducing the number of times the machines must be set up and run. Gary Fenical is the Senior EMC Engineer at Laird Technologies and is the author of many articles on EMC requirements for medical devices, Mutual Recognition Agreements, and guidelines to meet the essential requirements of the EMC Directive.


A recent study reveals radiation from solar events is unlikely to affect earth & the dose of radiation emitted during the events isn’t enough to harm people.
While protecting the radio and jumper cables from the elements, the carrier class RF shielding allows for better channel planning and increased performance by providing a lower noise floor with higher sustainable air rates and fewer errors. We rely upon superior construction technique and quality materials to achieve owner, architect, and contractor satisfaction.
ETS-Lindgren offers two primary types of RF floor systems: monolithic and modular cell type.
If you require further details regarding the transaction data, please contact the supplier directly. This energy can adversely affect circuit performance or even, if high enough, cause damage to human brain cells or other organs. Today’s designer must create a circuit board that has the lowest possible emitted radiation while operating at top speed to meet its performance goals.
Good use of ground planes and wiring layout that minimizes parasitic capacitance and ground loops goes a long way toward minimizing EMI. Differential-mode currents, flowing synchronously through both signal and power distribution loops, produce time-variant electromagnetic fields and, on simple one- or two-layer PCBs, loops are formed by the digital signals being transferred from one device to another that return by means of the power distribution traces. The resonant frequency is the frequency where integer half-wavelengths correspond to the dimension of the shielding enclosure. In addition to metal shields that surround key circuits, additional shielding in the form of gaskets and other materials are often used to effectively shield as much of the entire enclosure as possible. Unfortunately, designers often leave shielding as a last option since the shields can be installed once the design is completed. Samples from Laird Technologies, Würth Electronics, FotoFab, TDK, and 3M are shown in Figure 1. Additionally, the ability of the material to reflect the signals is controlled by both the permeability and conductivity. However, shielding gaskets typically fall into four principle categories: beryllium copper and other metal spring fingers, knitted wire mesh, conductive particle filled elastomers, and conductive fabric-over-foam. There are many factors to consider and designers should have a comprehensive knowledge of circuit design, EMI control, mandatory specifications, environmental issues, and other factors.
The FA Series covers a wide frequency range (10MHz ~ 18GHz) to provide excellent suppression of high frequency radiated noise, conduction noise, and electrical surge. The material is thin, lightweight, and flexible and can be applied to a variety of applications with the adhesive tape.
The Shielding chamber requires a large space and the price is higher, is not conducive to mass production of the production units, so the shielding box is a good replacement.
Considering RF shielding materials at the beginning of the application design phase assures that the right materials are chosen and that issues can be identified and dealt with early on in the process—a strategy that saves money and keeps the project on time. Taking these factors into account can save time and money and help assure peace of mind when designing an electronic device.
The plan will ensure the RF shielding material meets mandatory requirements and will help get the end product to market in a timely and efficient manner. At this time, it is wise to contact a manufacturer that provides comprehensive engineering services to assist in selecting the proper and least expensive solution to meet the RF shielding predictions. If it is known at the beginning of the project that the design requires shielding materials such as PCB, shields, RF gaskets, ferrites, etc., it is easier and more cost effective to design in standard products. Many times a standard profile or shape may come close to doing the job but just will not work.
Sometimes it is just a matter of changing the base material or the thickness of the material. Except for elastomers that continue to improve under compression, tests have shown that other gaskets yield little or no improvement in performance once good contact has been established. This arrangement eliminates the need for periodic threaded fasteners to preserve the shielding effectiveness of the enclosure. Gasket material should be mounted where it is least likely to be damaged by people or objects. If the mating materials must be environmentally protected, the protective coating should be electrically conductive. Tables are available that provide a list of compatible materials, along with the various platings that are available. This allows the manufacturer to acquire larger amounts of material at a better per-volume price. Specify a material the manufacturer uses frequently, and some of the savings of buying in volume will be reflected in the final price of the shielding design. There are many other considerations, including the selection of an appropriate gasket type, enclosure material, surface finish, and closure mechanism.
The FAE can provide guidance as to the most economical choices in terms of materials and labor.
The modular floor system is the quickest to install, while the monolithic floor system protects against non-catastrophic flood events and is the recommended floor system for all MRI applications. This article will examine some of the approaches and off-the-shelf products that can be used to minimize RF interference through the use of shielding and ground planes to prevent spurious signals from interfering with wireless system operation. Thus the goal in any RF design is to reduce emitted radiation to a level that meets or stays below any mandated industry requirements for operation, safety, and health. These loops also act as antennas and pick up the time-variant electromagnetic fields, which create noise in the loops.


However, by incorporating shielding considerations from the beginning of the design process, designers can deliver a more cost-effective and generally more efficient system design.
In addition to the many off-the-shelf solutions, designers can work with the shielding vendors to create a custom shape to meet their specific system needs. Part of the design challenge for shielding must take into account such issues as airflow, mechanical strength, and still other factors. Each of these materials has distinct advantages and disadvantages, depending upon the application.
The FA Series is available in sheet or roll form but can be die cut to custom shapes and sizes.
A generalized breakdown of the costs for producing RF shielding materials is one-third material, one-third labor, and one-third overhead. If problems are uncovered too late in the development phase, a product might fail to meet requirements and not make it to market at all. However, there are quite a number of such hollow profiles available as standard products, and they are therefore less expensive than custom-molded shapes. Usually, it is a matter of cutting to length, removing fingers, adding holes, extending or reducing dimensions, or adding secondary operations such as bends or various geometries. For large doors, it is usually better to mount the gasket on a door frame where some protection is afforded.
If the gasket includes a separate environmental seal, that seal should be facing the external environment. Other material such as phosphor bronze, stainless steel, or cold-rolled steel may be an acceptable choice. Effective forecasting also allows a manufacturer to dicker with suppliers, thus further reducing material costs. Up-front costs are higher than choosing secondary tooling, but a lot of handling down the road is eliminated. For those inexperienced in enclosure design, construction, and testing of a prototype is highly recommended.
The FAE will also provide important information on fasteners, spacing, and base material thickness, an important factor in dealing with closure forces of the gasket on the case of the apparatus.
Many shields incorporate apertures (holes) in their structure to allow air to flow through, helping reduce thermal buildup in circuit sections that dissipate significant amounts of power. The experts on the Board are charged with providing advice and overseeing product development.
RF shielding is a complex subject and requires experience and trained engineers familiar with both the nuances of the materials and geometries required.
Similarly, there must be a solid ground plane level to provide the “sixth” side of a Faraday cage.
Most standard profiles can be modified in various ways to provide a custom RF gasket or PCB shield without incurring the costs of custom tooling.
In such cases, it is necessary to work with a knowledgeable engineer who knows what modifications can be made to the standard products to produce an altered product that fits a particular design. However, if a custom product is required, it is imperative that an engineering company be chosen, rather than just a manufacturer. A designer must be knowledgeable about the qualities of a particular gasket and the demands of a specific application. The cost of maintaining close tolerances will?greatly exceed that of opting for larger shielding gaskets. It may be deliberate, or it may occur incidentally—for example, on the hinge side of a door when the gasket is used in compression. For removable panels, it is usually better to mount the gasket on the panel so that when the panel is removed, the gasket is no longer near the work area.
There are also other considerations such as pre-plating with bare edges allowed, or even in lower volumes, allowing one bare edge so that the part can be processed in batches rather than one at a time.
High-volume tooling is also a factor in holding down costs when modified standard products are used. Simply going to a catalog and trying to pick out an RF gasket or shield for an application rarely works. If a product has proved reliable in many applications, the manufacturer will likely keep making it available to customers. A true engineering company will have an engineer properly design the required custom product.
Be sure to choose a gasket with both minimum compression force and maximum working height range, and be sure to provide a positive stop.
In either case, engaging the gasket from the wrong direction will damage the fingers and will impair shielding effectiveness. If RF gaskets are required, it is essential to provide the proper sized and shaped surface to achieve effective installation. When designing custom shielding, try to incorporate readily available parts (such as a “D” lance) whenever feasible.
Does the application require the exceptional properties of beryllium copper (BeCu), or will a less expensive material work?



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