EMI Filters and RF Shielding Products
- Serving the RF Shielding Community Since 1978 -
About Us
Contact Us
FOIL Ethernet Filters
  - POE Ethernet Filter
  - PLENUM Ethernet Filter
  - EMP Ethernet Filter
FOIL Filter Support
Used Shielded Rooms
Used Screen Rooms
Used Anechoic Chambers
Other Used Items
RF Absorber
RF Shielding Services
Request A Quote
Or More Information

GigaFOILv3-PLENUM™ Ethernet EMI Filters

Plenum Ethernet EMI Filters
The GigaFOILv3—PLENUM™ is the latest addition to the DJM Electronics FOIL™ line of Ethernet filters. FOIL™ filters utilize Patented technology and are the only EMI/RFI filters for Ethernet on the market that offer 100dB performance from 10kHz to 10GHz and higher. Housed in a single, convenient filter package, FOIL™ Ethernet Filters are the easiest and most reliable solution for bringing Ethernet access to all varieties of shielded rooms and enclosures.

Standard signal line filters rely on capacitors and inductors to eliminate unwanted RF signals. However, these types of filters often eliminate the high frequencies that make up the sharp edges of high speed digital square wave signals thereby degrading the integrity of the signal. In order to avoid this side effect, it is necessary for standard signal line filters to have extended passbands that allow the higher frequencies to pass unimpeded. Also, it is important to note that standard signal line filters do not differentiate between Ethernet signals and undesirable signals. They act like a "hole" in the shielded enclosure to all signals - good and bad - within the passband.

Unlike standard signal line filters, FOIL™ Ethernet Filters utilize a fiber optic isolation link (FOIL) to maintain 100dB shielding integrity. The filter converts ONLY Ethernet packets, so there is no passband and no transmission of unwanted signals.

We guarantee that FOIL™ Ethernet Filters will not interfere with your network, increase hop counts or degrade network performance - a common problem with standard signal line filters.

The new PLENUM version of GigaFOIL™ filter is specifically designed for use in plenum spaces. The “plenum space” in a building is typically located above drop ceilings and may be used to house communication cables, electrical wiring and air handling equipment. Because materials in plenum spaces may pose a serious hazard in the event of a fire, stricter safety standards are applied to plenum rated products. The GigaFOILv3—PLENUM™ incorporates low flammability materials and wiring (as tested to the UL 94 standard) and provides for hard-wired power using a specially designed NEMA enclosure for combined AC/DC connections (compliant with the UL 508a standard). The GigaFOILv3—PLENUM™ is UL Listed and has successfully passed UL 60950-1 and CSA C22.2 No. 60950-1 testing.

Filter Performance

Shielding Effectiveness

100dB from 10kHz to 10GHz

Insertion Loss*

100dB from 10kHz to 10GHz

Radiated Emissions*

FOIL™ Ethernet filters are active filters and produce a limited amount of radiated emissions inside the shielded enclosure. Please contact DJM Electronics for information regarding your particular application.

Insertion Loss performance is extrapolated from tests performed using a method as close to MIL-STD-220B as possible. The nature of twisted pair cabling and RJ-45 connectors makes testing to this standard extremely difficult.

Radiated emissions tests were performed using a method as close to CISPR22 and FCC Part 15 as possible. The nature of the filter required it be mounted in a shielded room and tested from 3 meters away instead of on a standard OATS. Actual emissions performance may differ from filter to filter.

Network Performance

Auto MDI/MDI-X Configuration

Automatically detects and configures the twisted pair port on the converter to the correct MDI or MDI-X configuration.

Auto Negotiation

Automatically configure 10Mbps, 100Mbps or 1000Mbps

Flow Control

Supports 802.3x Flow Control for Full-Duplex mode and Back Pressure for Half-Duplex mode.

Hot Pluggable

Can be plugged in/out without affecting the filter or other links.

Auto Link Restoration

Automatically re-establishes the network link after a link loss.

Communication Standards

  • IEEE802.3 10Base-T (Ethernet)
  • IEEE802.3u 100Base-TX (Fast Ethernet)
  • IEEE802.3ab 1000Base-T/TX (Gigabit Ethernet)


File Number



  • UL 60950-1
  • CSA C22.2 No. 60950-1

Air-Handling and Plenum Use

Suitable for use in environmental air space in accordance with Section 300.22.C of the National Electrical Code, and Sections 2-128, 12-010(3) and 12-100 of the Canadian Electrical Code, Part 1, C22.1


  • Operating Temperature: 0ºC - 55ºC (32ºF - 131ºF)
  • Humidity: 5% - 90% (non condensing)
  • >


Filter Housing

  • 20 ga zinc plated cold rolled steel
  • 1" NPS threaded penetration w/brass mounting flange nut and mesh gasket

Power Requirements

  • Input: 100-240VAC; 50/60Hz
  • Output: +5V / 2000 mA minimum
  • 10ft Plenum Cable; Red Lead Positive


5.50" x 3.25" x 2.50" with 3" threaded penetration (1" NPS)


FOIL Ethernet Filter Drawing

Typical Configuration

Plenum FOIL Ethernet Filter Configuration