I need to amplify our WiFi signal into a large walk-in freezer. Currently, the signal gets everywhere around the freezer, but does not penetrate the steel walls.

What would be the best and cheapest way to get a strong signal into the freezer?

UPDATE: I purchased an Engenius ENH210. I'm planning on mounting this inside the freezer and running this directional antenna or something like it outside the freezer by connecting it to the ENH210 using a cable like this. Feedback?

Also, am I looking at substantial loss in data transfer speed if I use a much longer length coaxial cable to reach a better signal, such as this one?

  • 9
    Um...Can I ask why? Jan 15 '13 at 19:40
  • Does it have a window? You may be able to position your AP in front of the window in a location where the signal can go through the glass. Jan 15 '13 at 22:45
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    Of course you can, KronoS. I have an inventory system I need to have connected to our intranet.
    – OStrich
    Jan 21 '13 at 19:28
  • It has no window, but we may end up installing a heavy duty panel door so it would end up with space for an antenna to be ran and installed. THANK YOU EVERYONE FOR YOUR FEEDBACK!
    – OStrich
    Jan 21 '13 at 19:31
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    I know this is a bit late, but a flat ethernet cord may have been a good alternative to a round one if you went under / over the door instead of drilling, or whatever method you used. If you drilled I would have just said to use a round cable.
    – cutrightjm
    Feb 14 '13 at 22:56

Getting through the walls is going to be nearly impossible - they effectively make a Faraday cage... Your best bet is to get an AP that can tolerate being inside the freezer and run it in with a hardline Ethernet cable.

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    As an alternative, you can use an AP with an external antenna and only put an antenna inside the freezer, put the AP outside (thus no need to use an AP rated to -18C or whatever the temp is inside the freezer).
    – haimg
    Jan 14 '13 at 20:34
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    @haimg raises a good point, but note that most freezers have pretty good seals on the entrances, so routing that cable in without drilling holes through the wall of the freezer may be nontrivial.
    – Shinrai
    Jan 14 '13 at 20:52
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    Do you have a standard 120VAC power plug inside the walk-in freezer room? If so, you could try Ethernet over Power to a small, rugged AP or repeater inside the freezer. You wouldn't have to drill any holes in the freezer and the freezer's efficiency would stay the same. Also, I'm sure this problem has been faced many times by wholesalers such as Berkeley & Jensen's; they probably have product scanners that can operate offline and upload the results when they exit the freezer, eliminating the problem. Jan 14 '13 at 22:05
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    @allquixotic as an outsider, im interested in this; would the freezer's condensor or other equipment make issues on the PoE ? I always believed domestic freezers were a known source of electrical noise, so i'd have imagined the same would be true for a walk-in one ? assuming the chilling equipment is on the same circuit as any interior plug of the freezer.
    – Sirex
    Jan 14 '13 at 23:34
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    Poe != ethernet over power lines. I'd guess a room sized freezer would be running on a seperate, higher voltage circuit
    – Journeyman Geek
    Jan 15 '13 at 3:08

The easiest thing to do is probably going to be to drill a hole through the wall of the freezer (or use an existing one), and run microwave coaxial cable through the hole. Back when I worked for a wireless ISP, we used Times Microwave LMR cable for this (we were going outside the building, not into a freezer). On the freezer side, you put a low-gain outdoor-rated antenna (omni or panel, depending on location in freezer, check the radiation pattern to see that it covers the freezer), connected to the coax. Make sure to weather-seal the connection(s), you don't want water getting in.

This setup works for outdoors, your freezer will probably be a much nicer environment. No UV from the sun, etc. You can put a plastic guard over the antenna if you need to protect it from impact. Metal will block the signal.

Seal the hole in the freezer wall you run the coax through. You just want to stop air leakage. The efficiency impact on the freezer is going to be unmeasurable, as long as you don't have a lot of air leaking. (It's a ¼–⅝" hole compared to a surface area a hundred thousand times larger).

On the other side of the coax, you attach your access point. Use only one of the antenna connectors, and configure the access point to only use that antenna. (APs are usually not designed to have the two antennas on one AP in different locations, and it will cause issues).

Your coax can be basically as long as you need. Each foot of the coax causes some loss of signal strength, if you go long enough (hundreds of feet) you'll have to switch to more expensive (thicker) coax, and eventually add an amplifier inside the freezer. An outdoor amp will be fine, unless this is a -40 walk-in freezer, but keep the power low. If you need a setup with an amp (and you really shouldn't), find a wifi contractor.

Use a different access point to serve clients outside the freezer. Use the same SSID, and connect the two access points to each other with Ethernet. Each AP should be on a non-overlapping channel (use 1, 6, and 11 in the US, unless you really need more than 3, then 1, 4, 8, 11). Clients should roam between the two seamlessly.

If you have any budget for this, the folks who install satellite dishes should be able to do all of the cable & antenna work. Won't take them too long, either, so it shouldn't be that expensive. Or you could find someone who does wifi networks to handle the whole thing.


As was said in the comments to the other answer, you can set up an AP outside the freezer, with a remote antenna inside the freezer. Some routers have multiple antennae, or allow for additional antennae to be attached, for additional range/coverage. If the AP has at least two antennae and they use BNC connectors, all you have to do is mount the AP outside the freezer, disconnect one of the antennae and run a length of BNC coaxial cable into the freezer with the antenna reconnected to the other end. Some measure of frost protection to prevent shorting would be advisable; you could wrap the connection in electrical tape, or give it a shot of that Flex-Seal stuff. This should get you connectivity both inside and out, without having to have two APs (and thus having the problem of dropping and reconnecting to different wireless APs as you go in and out).

  1. Connect a long ethernet cord to an access point or router
  2. Open the freezer and walk into it, make sure theres slack on the ethernet cable
  3. Attach the access point to the ceiling
  4. Enjoy your wireless signal inside of your freezer
  • The seals on freezer doors are tight, that cable would be destroyed in days.
    – Shinrai
    Jan 21 '13 at 18:39

Test if you get cell phone service inside the walkin. You could possibly set up a personal hotspot inside the walkin. Unfortunately this would not be running on the same network as the one outside. In that case a VPN might work.

  • 2
    You know someone who makes a personal hotspot that's rated for use at temperatures below freezing? Jan 16 '13 at 19:00

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