When electronic devices receive strong electromagnetic waves, unwanted electric currents can be induced in the circuit, interfering with intended operations. In military and aerospace systems, such failures can compromise mission performance, put multimillion dollar assets at risk, and even cost human lives.
EMI filters are one of the first lines of defense against these disruptions. EMI filters are passive electronic components designed to suppress high-frequency noise and prevent electromagnetic interference from disrupting sensitive systems.
EMI filters normally consist of passive components, such as capacitors and inductors, connected to form circuits designed to shunt unwanted high-frequency energy to ground to suppress high-frequency noise and prevent electromagnetic interference from corrupting sensitive RF, timing, and control circuits.
The inductors allow dc or low frequency currents to pass through, while blocking the harmful unwanted high frequency currents. The capacitors provide a low impedance path to divert the high frequency noise away from the input of the filter, either back into the power supply or to the ground connection and effectively removing it from the signal or power line.
To maintain performance under these stresses, military and aerospace-grade versions are manufactured with stable dielectric materials that maintain capacitance and balance to minimize parasitics. EMI filters also undergo stricter manufacturing controls, often with 100% visual and electrical inspection and traceability for every material lot.
To meet these requirement, components are typically sourced from aerospace or military certified suppliers such as Johanson Technology of Camarillo, Calif. For more than 60 Years, the company has designed and manufactured multi-layer ceramic capacitors, EMI filters, and other critical components for high reliability applications.
While manufacturing is performed in North America to support scalable production, expedited lead times, and ITAR compliance, all high-reliability testing and design to standards such as MIL-PRF-31033, MIL-STD-202, and MIL-PRF-55681 is conducted in the United States.
To meet the diverse requirements of military and aerospace applications, Johanson Technology offers EMI filters in a variety of configurations and form factors.
One example is Johanson Technology’s planar and discoidal filters, which incorporate built-in filtering components directly into connector bodies to suppress unwanted EMI or radio frequency interference (RFI) as signals or power pass through the connection point. These connectors are commonly used in environments where cables and interconnects act as antennas that can pick up or radiate interference such as high-speed data lines, control signals, or DC power converters.
Johanson Technology’s X7R discoidal filters, for example, feature multilayer ceramic construction and a geometry enable dramatically lower equivalent series resistance (ESR) and equivalent series inductance (ESL), critical features in high-frequency decoupling and filtering.
Circumferential grounding provides infinite paths to ground, ensuring optimal filtering performance of the filter. The durable substrate construction provides protection against damage caused by thermal and mechanical stresses.
Often used in sensors and transducers, planar filters employ a flat, layered structure that integrates many filter lines into a single, thin unit, ideal for high-density connectors. They provide superior filtering performance, mechanical strength, and are more compact than discrete solutions such as tubular capacitors.
For more information, contact Johanson Dielectrics at (805) 389-1166, visit web site: https://www.johansontechnology.com/ppr/military-aerospace/ or e-mail: kvilla@johansontechnology.com.