Shield Your Wireless Router/Modem From RF Energy




Introduction: Shield Your Wireless Router/Modem From RF Energy

About: When I was a boy, I was amazed how my grandfather could make flotsam and jetsam into useful things. I am proud that I have inherited some of his skill.

Radio Frequency energy, generally called RF, is often a pain in the neck. It occurs when a transmitter nearby forces its signal somewhere where it is not wanted. I have seen it in the form of a herringbone pattern on the screen of a TV set, come through one receiver when I am transmitting on another, and cause a preacher to have to pause his sermon until two CBers finished what they wanted to say. It can have some connection to the transmitted frequency, or it can be a totally unrelated frequency being forced into the receiver by pure power or proximity.

In this case, RF was getting into my router/modem whenever I transmitted either voce or Morse Code, causing it to reset. It would come back on after a couple of minutes, but nobody could use the Internet when I was using the radio. Including me.

[This photo and the last one show my modem sitting on top of an unrelated scanner receiver. It's hard to see but the copper mesh covers the front - and rear - of the router.]

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Step 1: The Idea Behind the Solution

Once I realized what was happening, my solutions were plain: enclose the modem/router in a Faraday Shield [an enclosure made of some type of conducting material surrounding the device needing protection] and - since the wires connecting to the modem/router were undoubtedly acting like antennas and feeding radio frequency (RF) signals directly into the device - to install chokes to block the signals.

It's not like I run a lot of power; neither one of my rigs puts out more than 100 watts, It's just that the antenna is almost directly over my den where the modem/router is located, and no further than maybe thirty or forty feet away from the Ethernet cable, telephone wire, and power cord.

My first effort involved wrapping the modem/router in aluminum foil. I left both ends open to help reduce the heat buildup and to allow me a way to connect the wiring, but the unit got pretty warm, anyway. It worked better than it did without the shield, but it was obvious that the RF was coming in through the open ends, because after a few seconds, the unit was shutting down again.

My next effort involved wrapping the modem in copper mesh. That actually was easier to find than I thought it would be. I found a twenty foot roll of the mesh online at a pest control company for about ten dollars. Craft stores sell it, also. As it turned out, the mesh is actually woven into a tube, so all I had to do was cut off a piece and slip it over the modem. (I did this with the electric connection, ethernet cable, and telephone wire attached.) Then I used regular cotton thread and sewed the sides up, so the modem was completely enclosed. I grounded it using an alligator clip connected to a ground wire; that in turn runs to a ground rod.

The proof is in the performance. Now, when I transmit, I can still use the computer.

Step 2: Problem Solved

As the modem is also a wireless router, it has two antennas, I had to make a couple of tiny holes in the mesh to slip them through.

Once I had finished, the modem was completely surrounded with copper mesh, which I also connected to ground by means of an alligator clip connected to a ground wire.

Although it was an irritating problem, it was simple to solve. [Remember to use the snap on ferrite chokes, too. You can find them online, too. I used type 43. They cost about $1.65 each ]

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    3 Discussions


    4 months ago

    I have a modem/router upstairs and a treadmill downstairs. Whenever I used the treadmill the lights on the modem/router went crazy and we lost internet. I tried connecting the treadmill to a different circuit, connecting the modem/router to a UPS (and running it on battery) and using several A/C surge/filters, however nothing worked. Finally, I found online that some people had success in solving this issue by using a Tripp-Lite surge suppressor. I bought a Tripp-Lite model ISOBAR4ULTRA (4 outlets) and plugged the treadmill into it. Success! No modem/router issues and internet is stable when using the treadmill.


    5 years ago on Introduction

    WOW, maybe that is the problem with my Zyxel modem-router. Thanks for sharing this, tomorrow I will try with aluminum mesh I have, leftover in my workshop.