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Boosting Cell Phone Signals in Strange Places?
hedgemage asks: "I work at a retirement home and we have trouble with the cell phones that our nursing and maintenance staff use. The problem is that our nursing home area is built into a lower level that was originally constructed as a fallout shelter in 1960. There's a lot of solid concrete in the walls and ceiling. We have paid out tens of thousands to try and get an on-site mobile to work using NEC Dterm PSII phones, but they have proven absolutely unreliable (not just in the bomb shelter but throughout the campus) and the only solution our telecom provider has is to install several thousand dollars more in transceivers. If we could use ordinary cell phones, it would be ideal for everyone. Is there an off-the-shelf solution that could boost regular cellular signals in our bomb shelter?"
The problem is that our nursing home area is built into a lower level that was originally constructed as a fallout shelter in 1960. There's a lot of solid concrete in the walls and ceiling.
Propose management to relocate the retirement home to a nicer place with, for example, windows and sunlight. Jesus man, who the hell make older folks live in a former fallout shelter? It's really sad. Tell me where it is so I know never to send my mother there...
"A door is what a dog is perpetually on the wrong side of" - Ogden Nash
It's not a great solution but it's cheap and simple.
Mea navis aericumbens anguillis abundat
This is what I was going to propose as well. Passive is the way to go, simply because you should be able to do this without running afoul of the FCC.
Here are a few more details to help with this:
(1) Make sure your service provider is one of the cellular carriers in the 800 mhz band. While this will work for both cellular and pcs frequency bands, generally speaking the 800 mhz will have a slight advantage for penetration within buildings. At this point you will probably need every edge you can get.
(2) Locate the closest cell tower that provides coverage to your location.
(3) Get a directional high-gain antenna and mount it outside pointing at the cell tower.
(4) Determine where the inside antenna will be placed, and then figure out the beam pattern/width you need. For example, if you put it in the center of your area, an omni antenna will probably work, if you put it on one end, a directional antenna with the main lobe pointing inside the area.
(5) Connect the two with low-loss coax. You may need to use 5/8, 7/8, or larger coax depending on the length of the run from the internal antenna to the external antenna.
You are going to want antennas that are tuned to cover the entire range of the cellular band, not just tx only or rx only antennas.
If the passive system does not work, contact the wireless phone provider you are using, and ask them about setting up a micro-cell, repeater, or enhancer to cover your area. You may need to volunteer to pay for some or all of the physical equipment and provide electricity for it. Since they are putting in the equipment, you still shouldn't have any problems with the FCC.
I don't know how well this type of passive antenna configuration will work. I've seen mixed results in the past when I was playing around with things like this. It all depends on how much boost you really need to make things work. If you have a budget to make this work, your best bet might be a powered system put in with help from your wireless provider.
. 62,400 repetitions make one truth -- Brave New World, Aldous Huxley
Directional antennas on a rooftop that points directly to the nearest celltower(s).
Omnidirectional antennas indoors at strategic location, one indoor antenna per external antenna.
Use low-loss cabling between the antennas. The cabling and installation of the cables may be the most expensive issue. As this is a completely passive solution you shouldn't have any trouble with FCC.
There are certainly disadvantages with this solution too, and it may not work or be feasible for your situation.
If builders built buildings the way programmers wrote programs, then the first woodpecker would destroy civilization.
You may be making things more complicated than they have to be by insisting on the absolute newest technology. Sometimes an older technology fits the situation better. For instance, if you just run some land lines down there, you can install regular old cordless phones. With the base-stations and the phones both in the sheltered area together, reception should be largely unaffected by the super-thick walls, and Bob is your uncle.
Cut that out, or I will ship you to Norilsk in a box.