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Gigabit Power Over Ethernet (POE) EMI Filters

Power Over Ethernet (POE) is a convenient way to power devices inside shielded enclosures and chambers without using AC adapters which can radiate significant RF interference. The GigaFOILv3-POE™ is IEEE 802.3at-2009 Type 2 compatible -- meaning it can supply 52VDC, 600mA at the filter output. In addition, the filter acts as an injector (also known as a Power Sourcing Equipment or PSE), so it does not require a POE input. Once the filter is plugged in, it will determine if the device connected is POE compatible and then begin negotiating the power level required by the device. If the device is not POE compatible, then no power is injected onto the Ethernet cable, so you don't have to worry about "frying" your non-POE devices.

As a member of the DJM Electronics FOIL™ brand Ethernet filters, the GigaFOILv3-POE™ utilizes patented technology and is the only EMI/RFI filter for Power Over Ethernet on the market that offers 100dB performance from 10kHz to 10GHz and higher. Housed in a single, convenient filter package, all of the 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. Even the best standard signal line filters offer only 70dB from 50MHz to 10GHz and will only work with 10Base-T. There are no Fast Ethernet (100Base-TX) or Gigabit Ethernet (1000Base-T) standard signal line filters available on the market. 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.

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)
  • IEEE802.3at-2009 (Power Over Ethernet PLUS)


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: +52V / 1350 mA minimum
  • DC plug type: center positive


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


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


FOIL Power Over Ethernet Filter Drawing