EMI/RFI Filters


EMI/RFI Filtering

EMI/RFI Filtering specialist capabilities

EMI/RFI Filtering capabilities & products

Tubular Image

The RFI SPECIALTY COMPONENTS program brings together from one source a full range Tubular, or Cylindrical, filters for different applications:

Filters qualified to Mil-PRF-15733 are available from Ultra EMS, which offers the greatest number of qualifications for the most popular filter mil spec. Catalog sheets reference the appropriate qualified mil spec numbers for easy cross-reference. Upon request EMS can also propose a non-QPL option. For applications requiring Higher Reliability, the RF6900 Series was designed and developed according to Mil-PRF-28861. These filters are available in many circuit configurations and are certified to meet all the applicable requirements. 

A third type, the Sprague cylindrical filter, remains a popular option for engineers seeking an excellent military-grade catalog filter. These have been the filter of choice on many defense platforms and continue to be selected by today’s design engineers.


Custom and Rectangular
Custom and Rectangular Image

The RFI SPECIALTY COMPONENTS program from EMS has the capability of designing and manufacturing EMI/ RFI filters in virtually any shape and size. Most filters in this “Rectangular” category are the result of an open exchange of technical details between EMS and the end-user. While rectangular-shaped packaging is the more common, we accept the challenge to accommodate an application’s unique requirements for size, weight, shape, termination, or mounting without compromising performance.

Popular applications include power and signal filtering for defense and aerospace equipment, for radar, for communication, for shielded and secure rooms, and others.

Information about FILTRON Powerline shielded room filters is available by contacting the factory or your local representative.

For applications that may involve Transient Voltages or Electro-Magnetic Pulse (EMP) technical information that is specific to these applications are also available.  


EMP & Voltage Transient
EMP & Voltage Transient Image

The RFI SPECIALTY COMPONENTS program includes a range of EMI/RFI filters that are designed to protect circuits against very high energy transient events. Examples include:



Mil STD 461
Mil STD 461 Image

Ultra EMS can provide EMI filters specifically designed for reducing emissions and lessen susceptibility for compliance to Mil-STD-461. The filters will comply with the restrictions on Leakage Current for both 60Hz and 400 Hz power systems but are characterized with Insertion Loss data directly related to the Mil-STD-461 testing methods.


Shielded Rooms
Shielded Rooms Image

FILTRON products were first designed and built in 1946 to address the growing demand for devices offering protection against electromagnetic interference produced by radar, computers, radio transmitters and receivers, as well as by motors, generators, and switches. Applications for these filters are found in many commercial and private test laboratories, and at the secure room installations in military and diplomatic facilities. All FILTRON products are made in America at the facilities of Ultra EMS Development Corporation. Additional Shielded/Secure room filters that have been designed and developed by EMS and the RFI Corporation are an important part of the RFI Specialty Components program. Examples include a telephone line filter that is available in multi circuit assemblies, and a power line filter which is designed to be direct-mounted through the wall of a shielded room or cabinet.

Additional information on these and other products is available in the RFI Specialty Components Programs general catalog, or by contacting the factory.


Tempest Image

The RFI Specialty Components of ULTRA EMS includes lowpass power TEMPEST filters that are deployed in defense and in private installations to prevent power lines and other outlets from acting as transmitters of electronic data. With a TEMPEST filter, sensitive information will not become conducted EMI signals leaking from PCs, servers, telephones, etc. These filters are recommended for use in shielded rooms, secure communication areas, as well as in shipboard electronic installations. Pictured is one of many possible TEMPEST filter designs.