Photo courtesy of Pepro LLC
Think about the need for EMI shielded ventilation panels – what they do and why you need them. Are you fully protecting that hardened enclosure with the right option? Does it measure up to standards for your civilian or military application?
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Honeycomb Waveguide – An Attenuation Performance Explanation of a MAJR Products Honeycomb Waveguide Panel due to the Effect of a Waveguide Beyond Cuttoff Principle
A shielding honeycomb waveguide panel is a product that lets air flow into and out of an EMI/RFI shielded enclosure. The entering fresh air may be either cooled, heated, or at ambient temperature depending on the shielded enclosure environment and contents. For electronic equipment, the primary reason for airflow is usually to cool electronics; if a manned military shelter the reason is to circulate fresh air and to either cool or heat the air depending on the external environment.
Depending on the wavelength of the electromagnetic wave entering the honeycomb waveguide panel, every cell of the metal honeycomb core provides attenuation (shielding) to that electromagnetic wave and is described as a waveguide below cutoff.
Each individual honeycomb cell acts as a waveguide and because the honeycomb cell aperture (height and width) is much smaller than a half wavelength of the electromagnetic wave entering the honeycomb, the honeycomb cell attenuates the wave.
Attenuation is accomplished by increased wave impedance and reflection cancellation as the electromagnetic wave propagates through the honeycomb waveguide thickness and number of cells. The thicker the honeycomb cell, the more attenuation the honeycomb panel will provide, therefore an approximation is Attenuation (dB) = 28 x Thickness / width.
Depending on the polarization of the electromagnetic wave, the only frequencies of the electromagnetic wave that pass without attenuation through the honeycomb cells are those that have a half wavelength dimensionally smaller than the diagonal dimension of the cell.
To learn more about MAJR’s Honeycomb Waveguide Panels or other products, like: EMI/RFI Shielded Ventilation Panels, EMI/RFI Shielded Fan Ventilation Panels, EMI/RFI Shielded Air Filtration Panels, or EMI/RFI Shielded Honeycomb Ventilation Panels, visit our website and fill out the form or call us at 877-625-7776.
When ordering connector gaskets, military contractors and electronics, IT, andtelecommunication companies often find it challenging to find suppliers that both offer a comprehensive range of gaskets and can deliver orders within a short period of time. As a result, procurement professionals, purchasing managers, and others responsible for buying materials frequently spend hours researching suppliers looking for one that can cater to their specific needs. Since it is so difficult to find the combination of choice, quality, speed, and cost-effectiveness, it is not unusual for them to have to order from multiple suppliers to meet their various requirements.
That is why in June, we launched our new website, ConnectorGasket.com. It is specifically designed to provide our customers with a convenient, quick, and cost-effective way to fulfill all their connector gasket needs with just a few swipes, taps, or clicks.
To cater to the needs of customers from the military, consumer, industrial, instrumentation, and medical electronics sectors, as well as from the IT and telecommunications industries, we offer affordable QPL-qualified gaskets and commercial grade gaskets. There are currently four styles available for online purchase:
By creating their own accounts, customers can keep track of their orders and easily re-order when needed. Plus, by selecting the two-day delivery option, customers never have to hold up their production cycles due to late deliveries, thereby ensuring they can fulfill their own orders as scheduled. Companies that have factored long delivery times into their own production cycles—and by extension, into their order fulfillment capabilities—can leverage our fast delivery to reduce their production cycle times and offer their own customers speedier turn-around.
Customers are also encouraged to visit our main site, MAJR Products, where we offer many other types of gaskets, including military EMI/RFI shielding gaskets and custom-made gaskets that can be manufactured to companies’ precise specifications.
Interested to learn more? Go to ConnectorGasket.com to browse our products, place your first order, or request more information.
Sources:
Creative brief
Press release June 19
Any electronic device emits some level of electromagnetic radiation. Electromagnetic interference (EMI) shielding and radio frequency interference (RFI) shielding products are used when the EMI/RFI of an electronic product or system, in particular high frequency operations, necessitates attenuation of EMI/RFI to a specific level; the attenuation of a radiated emission to a certain level is designated in industry as shielding. MAJR Products EMI/RFI shielding solutions are able to meet even the most stringent EMC requirements.
Understanding antennas and electromagnetic fields is the first step to understanding EMI/RFI shielding. EMI/RFI shielding is important for achieving electromagnetic-compatibility (EMC) for electronic products including digital systems. EMC design is concerned with preventing electronic devices from not interfering with its own operation (crosstalk) in addition to the reduction of electromagnetic radiation that may interfere with other electronic equipment and systems when operating in an intended environment.
EMC design also involves preventing circuits from misbehaving as a result of ambient EMI/RFI from communication towers, aircraft, radio stations, etc… With digital systems’ ever-increasing frequencies and edge rates, EMC is becoming harder to achieve.
The shielding products produced by MAJR Products can be designed and manufactured to suit the unique needs of specific customer applications. In addition, with experience designing custom EMI/RFI shielding products, the engineers at MAJR Products offer customers flexibility from design, through prototyping / test, and into production.
While EMI/RFI Shielding has long been a requirement for military applications’ such as in high frequency electronics, there is also a growing need for microwave absorbing materials in consumer electronics such as wireless LAN devices, network servers, video equipment etc. Depending on the requirements of the application, microwave absorbing material can be tuned to function best at specific frequencies or designed to be used across a broadband frequency range. Along with tuned microwave absorber materials, Broadband microwave absorbing material is used in electronic products for a wide variety of markets including cellular and telecom, RFID tags, electronic devices, radar cross section reduction, and a variety of other antenna and electronic enclosure applications.
For shielding of RF and microwave applications, MAJR Products 6500 series Broadband Microwave Absorber material product line utilizes material that is elastomer-based, ultra-soft, thin, flexible, and easy to install in even the tightest of applications or irregular surfaces. This absorber can be supplied die cut or water jet cut to meet the exact product specifications. In addition, for installation ease the absorber can be supplied with a pressure sensitive adhesive, typically requested for use in general to high altitude or high vibration applications.
MAJR Products’ Board Level Shields (BLS) are manufactured specifically to meet the requirements of an individual project, we offer the following:
Contact MAJR Products For A Quote On Shielding Products For RF And Microwave Applications
See how MAJR Products can solve your electronics shielding equipment needs. Contact us for additional product information, free sample products, or to receive a quote on shielding solutions for RF and microwave applications.
A MAJR Products Corp. Article by Mike Oliver
What is Conductive Rubber?
Definition: Conductive Rubber is a generic term referring to any rubberized material with conductive properties which reduce or eliminate the EMI/RFI (electromagnetic interference and radio frequency interference) “noise” that is often associated with electronics.
While there are a handful of materials that might be considered Conductive Rubber, this article will be focusing on the three common material types. Multicon (oriented wire in either sponge or solid silicone) Conductive Silicone (metallized filled silicones), and Radthin (wire screen imbedded into silicone). Each material is unique in its construction as well as its performance. Please see product description below for more detail.
Multicon Material:
Multicon material is one of the most prevalently used forms of conductive rubber today. It’s a combination of silicone and conductive wire paths which provides a superior environmental seal while providing EMI/RFI shielding to frequencies up to 6 GHz.
Multicon is offered in either solid or sponge silicone with either monel or aluminum wires for conductivity. The conductive wires are dispersed throughout the width of the material to provide great protection against EMI/RFI contamination. It’s constructed in such a way that when pressure is applied to the gasket, hundreds of sharp wire ends become exposed making electrical contact with mounting surfaces.
Multicon can be provided in a wide range of thicknesses and widths to meet the needs of a specific application, or the material can be die-cut to meet various configurations.
Conductive Elastomer:
Another widely popular form of Conductive Rubber is Conductive Elastomer. Like Multicon, Conductive Elastomer can be die-cut to form a flat gasket but one of the large differences from other materials is that Conductive Elastomer can also be provided in a variety of different extruded profiles. Common profile configurations of Conductive Elastomers are: “D”, Round, “P”, Square, and Rectangular; these profiles can be extruded as a solid cross section or hollow depending on the compression required and height of the open aperture to be shielded. See Figure #1
Figure #1 Conductive Elastomer profiles (click image to enlarge)
In Conductive Elastomer the base rubber is usually comprised of compounds such as silicone, fluorosilicone, or EPDM (ethylene propylene diene monomer). The use of a specific rubber is based upon the properties unique to each and determined by the intended environment and application. For example, silicone is used for general weather sealing and high temperatures to 400 deg. F. Fluorosilicone is used for applications where exposure to jet fuel, gasoline, and alcohols are present. EPDM is used for applications where exposure to coolants, steam, phosphate ester, or where supertropical Bleach (STB) is used.
After choosing a specific rubber suited for the intended environment, a conductive filler must be determined. Some of the most common conductive metal fillers used are silver aluminum, silver glass, silver copper, and nickel graphite.
Determining the right filler is dependent on the level of shielding needed for a specific application, the more conductive the filler the higher the level of shielding achieved. Once the parameters have been determined, the table below can be used to establish which Conductive Elastomer is right for the application. If you’re unsure, feel free to contact us at emi@majr.com
Figure #2 Summary of conductive particle filled elastomers as specified by the MIL-DTL-83528 standard.(click image to enlarge)
Radthin:
While not as popular as either the Multicon or Conductive Elastomer materials, the Radthin gasket material can be a valuable asset when an ultra thin gasket that can withstand a wide-range of temperatures is needed. Often seen as a common gasket for connectors it can also be die-cut into custom shapes for other unique applications.
Radthin is comprised of a 24 mesh aluminum alloy wire cloth impregnated with 50 durometer neoprene or silicone rubber compound. The total thickness of either the silicone or neoprene Rathin is either 0.016 or 0.020 in. The temperature range of the neoprene Rathin gasket is -35 deg. F to 225 deg. F, the silicone Radthin is -65 deg. F to +500 deg. F. This makes it ideal in certain settings. See Figure #3
Figure #3 Radthin material – 24 mesh aluminum alloy wire cloth impregnated with 50 durometer neoprene or silicone rubber compound
Considerations with material choice:
When working with Conductive Rubber it’s important to remember that galvanic compatibility will also have an effect on which wire type or filler should be used. Galvanic compatibility is the corrosion potential between the conductive material and the metal interface or mating surface.
In some cases, one side of the material may be exposed to a different metal than the other; in this case, a conductive wire type or filler choice needs to be made where the difference in voltage potential between the dissimilar metals are as small as possible. See figure #4 below.
Figure #4 Galvanic compatibility chart derived from MIL-STD-1250 (click image to enlarge)
Where is Conductive Rubber used?
Used in industries including but not limited to Telecom, Military, Computing and Medical devices, Conductive Rubber gaskets are used in applications where there needs to be an environmental seal and good to excellent shielding effectiveness. As an example, but not limited to, electronic enclosures with removable covers (Fig. #5), military shelter doors / access panels (Fig. #6), Electronic displays for computing and handheld devices where conductive EMI/RFI windows need to be environmentally sealed and grounded.(Fig. #7).
Figure #5 An electronic enclosure with a removable cover (click image to enlarge)
Figure #6 Military shelter utilizing conductive rubber EMI/RFI gasketing on the perimeter of the door.
Figure #7 Conductive EMI/RFI windows to be environmentally sealed and grounded to an electronic enclosure. (click image to enlarge)
Conductive Rubber in any form is an important part of military and commercial electronic products. It enables these devices to meet radiated emissions and environmental requirements for use in many demanding applications throughout the world.
For more information on all Conductive Rubber materials and many other shielding products please visit www.majr.com