What exactly EMI/RFI means and why we need EMI shielded ventilation panels confuse most of us. To understand what EMI shielded ventilation panels are and why you need them for protecting that hardened enclosure, you need to clear some basic concepts.
All electronic equipment produces some unwanted electromagnetic energy that can interfere with the operation of other electronic equipment present nearby due to EMI transmission by radiation and conduction. Thus, to minimize the negative impact of EMI, the sources of undesirable electromagnetic energy may be shielded and electrically grounded. As such, with the help of shielding, both ingress and egress of electromagnetic energy can be controlled. In simple words, EMI shielding limits the amount of EMI radiation from the external environment that can penetrate the circuit. Moreover, it controls the EMI energy generated by the circuit from escaping into the external environment. For effective EMI shielding, the gaskets are used to absorb or reflect EMI.
Hardened enclosures of various applications and industries come in all shapes and sizes. Though most hardened enclosures are custom designed to meet specific requirements, they all have one thing in common: ventilation panel. This is a necessary requirement to allow cooling of sensitive electronic equipment, in addition to protecting it from EMI/RFI. The ventilation panels, also known as vent panels enable airflow through the honeycomb because the cooling capability is directly related to the volume of airflow per unit of time. The traditional vent panels consist of a metallic honeycomb material mechanically assembled into a stiff metallic frame.
To provide ventilation and EMI shielding, honeycomb filters are installed in an opening on the enclosure. The aluminum honeycombs are low-cost vent panels which provide lower levels of shielding effectiveness. While the more expensive steel or brass honeycomb is used for the applications that require a more robust vent panel with high levels of shielding effectiveness.
Now as we know the need for ventilation panels, next is the variation of EMI shielded ventilation panels. The different level of shielding requirement and environmental factors requires different variations of EMI shielded ventilation panel for hardened enclosures. These are:
Honeycomb Ventilation Panels: These vent panels use a waveguide honeycomb design to pull off greatest EMI and RFI shielding. As such, honeycomb vent panels are used to achieve the best possible EMI/RFI shielding without hindering the airflow pressure. However, while making a selection it is important to consider airflow requirements, types of mountings, and the type of shielding required.
Honeycomb Waveguide Panels: These are built with a series of honeycomb openings to ease the signals passing through ventilation openings. To put up with E-field or H-field attenuation, the frames are built from various materials. These panels are known for their advanced attenuation qualities and can be effectively used in electronics cabinets, military shelters or vehicles to ensure EMI or RFI shielding.
Shielded Air Filter Panels: Unlike providing EMI or RFI shielding, these panels are used when dust or other particulate penetration needs to be filtered. The EMI Shielded Air Filtration Panels can be coated with glutinous oil and can also be customized to specific applications.
Shielded Fan Ventilation Panels: EMI shielding and ventilation panels are necessary for your application, environment, and civilian or military. Built from honeycomb material, these panels are mostly demanded in civilian markets. This is because these provide better results at low-cost. They are available in a number of standard sizes and can also be customized according to specific requirements.