Cell signal amplifiers and boosters

[greygray]

Hello,

I have been looking around at adding a cellular signal booster to my home.
( I have about 1/8 bar ( iPhone 6S Plus ), -173dB at times I believe, I used a code to access a test mode on the phone, I can only place non "HD-Calls"  ) if I have -99dB or better.  If we had real wifi-calling not this HD-Calling ruse, none of this would be needed, I'm considering doing the below as a business. )


This is specifically NOT a micro-cell, fem-to-cell, Cellular Range Extender ( As Verizon calls it ) or other wifi to 3G or 4G gateway. This is a simple setup of an elevated point to point uni-directional antennae pointed at my nearest Verizon cell tower using the correct frequency range for the version and provider I have.  Then the signal will be amplified in power by a small power amplifier of some form, and then an omni-directional, indoor, ceiling mount-antennae to ideally spread the signal from somewhere ~1000 ft. and ideally up to ~5000 ft. radius ( at ideal power and signal conditions ).

You can buy these parts easily only, the antennas are everywhere, being careful to do as short as possible wire runs and buying only the best wire, you can get decent distance from one end to the other, though more than 100ft is probably a good maximum run of cable.  You can even buy window mount systems as packages as well.  And of course, there are a variety of power amplifiers made from a small handful of companies ranging from $50 to over $1000.

Is this a product I can make myself?  Would it be totally brain dead to take an old router at the correct frequency, 900 and/or 1.2 I believe are both used by cellular for 4G or maybe even 3G.  Regardless, they are usually set at max FCC allowed power, so I have my signal amplifier right there.  Some even come with antennae ports on them.  I would have to find routers that use modified firmware and believe I may have to do some hacking to get the software to just pass the signal through only amplified, but I am not sure.

Any products that could be salvaged for this part out of it?  Perhaps old stereo's, CB's, HAM Radio's, I have no idea, just spilt-balling here…

Outside of that, can I just build one from the ground up?  I know they use these in large commercial office buildings.  I see the repeaters mounter on the top walls and ceilings everywhere.  Somewhere, there is a aluminum box that has a powerful wattage repeater in it that is taking a signal from an outdoor mount antennae and spreading it all over the place to the benefit of building users and those closely as well.  I also see the wifi repeaters, but that is a simple and relatively known area to get into.  Can I fully DIY this? 

i know I can 100% DIY the antenna for outdoor and deal with the mounting pole and brackets and proper grounding/lightning protection.  I believe I can rig up the indoor multi-directional antennae.  Though I am stumped on the amplifier.

Further, I know the FCC has wattage limits.  I believe it is 4 watts total on the amplifier.  While I understand the importance of staying under the legal limits, I do live in an area where the closes person is many miles away.  I can get 1 bar if I hike up a hill.  I have power there, and solar is a simple option, so I can pick up the signal and amp the power up on the hill, meaning no long cable needed down to my home.  A ceiling mount omni-d and I am ready to figure out the amplifier issue.  I would like to be able to adjust it as much as a device of this nature would be beneficial to be adjusted.  If they made ready to go boards that I can turn a POT and change the frequency, that would be cool.  Power adjustments, being able to go above the US rated 4 watts, though I have no intention nor do I believe I will need to, I would like the ability as a way to learn how the amplifier works and it would probably come in handy with alignment and setup.  And perhaps I need more, from what I understand I can only Tx the max, but I will have loss in every cable, connector, junction, etc, so I have to measure the signal output, not the amplifier output.

I have googled as much as I can and end up in the commercial and home use section of this area.  Then there is the boat and RV crowd, who has a whole arsenal of the exact same products being sold in the current residential space, only marked up 200% because they are "Marine Grade", even though the identical one going for half price are the same exact thing, only rated "Outdoor Use Acceptable".  Identical down to the part number.  Boaters and RVer's get it coming and going unless they know what they are doing.

I can't possibly believe it costs $500 ( Seemingly the average price for a good amplifier, not including another $150 for 2 antennae and possibly a few hundred more in wire, perhaps $50 for a 3" galvanized pipe, cement, brackets, tools, and of course your time = ~$875.00 ) or around $900 for a full large scale 5000 sq. ft. setup.  Even the lower-end vehicle, marine, and RV options — which end up rating/performing the identically as the 1000 sq. ft. residential models sold under a slightly different name or design.

Really?  It is $500 in parts and labor to make a cellular amplifier?  Well, markup for profit, even at %50-75% still seems high for a small power amplifier.  They practically are giving them away in every non MIMO, non multi-band, not-made in the last 3 years wi-fi- router. if I get this correct, parts and labor on a small 1-6 watt cellular amplifier is going to be over $200 in parts and labor?

Thank all you wondering engineers and hobbyists that take the time to help new people into this scene out.

[TheSteve]

I don't want to discourage you but based on the information in your post I'd say you're better off buying one. There is no way you can take an router and make it work. There is no chance your phone works at signal level you posted. It takes real engineering and very expensive test equipment to make a proper cell amplifier/booster.

[Richard Crowley]

Yes, I agree. That kind of project/product appears to be completely beyond your resources, based on the questions you are asking.  It seems very much the case where "if you have to ask....".  I truly regret saying that, but the facts the facts.

It is possible that two or three individuals (out of the 10s of thousands) of people on this forum could design such a device. But not without the considerable resources of a fully equipped laboratory designed to work with UHF - SHF radio frequencies.  Including a full-lab Faraday cage.

[cvanc]

I'll have to agree this is not a homebrew possibility.  Also, are you sure about that -173 reading?  That's about what NASA receives from the Voyager deep space probes using gigantic steerable antennas.  And the Voyagers are out way past Pluto...

In any case good luck solving your problem.

[KJDS]

-174dBm is the noise power of a 50R resistor in a 1Hz bandwidth.

I'm quite capable of designing one of these, but if I needed one then I'd buy one. A more likely solution is just to get an external antenna attached to your phone. If there's some signal inside the house then it should be possible to make a significant improvement. It might mean that you're restricted to where in the house you can tether your phone to, but it would make it usable for very little effort.

[TheUnnamedNewbie]

While I don't fully understand your text, You should not be comparing a mass produced thing like WiFi with enterprise/"marine grade" cellular amplifiers. You are talking about a device that likely has a lot, lot higher build quality, robustness, reliability, and smaller market.

And I think you are underestimating the complexities of the 3G/4G networking protocols. As has been said above - the questions you ask seem to indicate you don't have the knowhow to make the device you want to make.

[_Andrew_]

I have come across these Chinese re-transmiting boxes before and have found to be temperamental or just don't work. Also in most countries they do not comply to the regulations.

The boost boxes, femtocell units from the mobile operators that use your home Internet connection to convey the signal can work very well but the box still needs to be able to pick up the mobile network for it to work.

It is also worth checking whether your network provider has a voip wifi app to connect your phone to the cellphone network via your home Internet connection. In some cases they incentivise the use of wifi as it can reduce demand on contested towers.

For phones that have an antenna connection visit http://www.rfiwireless.com.au/mobile-products.html#.VogDB-CnwXA there are probably amongst the best you can find.
I use one of there collinear on a good old motorola brick gsm car phone and I have never had it loose signal, even in the wilds of Scotland. But then it's designed for the Australian outback.

RFI Wirless do some low power repeaters and being by them they will most probably work but you will have to check on the suitability and your local regulations governing there use.

[garre]

You have been given some good advice to buy a unit.  Even buying a unit can be a bit tricky.  These units are bi-directional amplifiers and thus have amplification both in and out with filters to separate the two signals.  So setting up bandwidth and filters are critical.  Also cell carriers often use different frequencies for voice and data.  Thus you may need multiple amplifiers to get all your signals.  Another problem is that some carriers use different frequencies and thus some amplifiers will only work on certain carriers.  So even selecting amplifiers and antennas can be tricky.  There can be issues with interference from other carriers that can make the cell boosters not work properly. So selecting the right equipment can be difficult, let alone trying to build one.

[rfeecs]

One of the major US manufacturers of these devices is Wilson Electronics:
http://www.amazon.com/Wilson-Electronics-DT-Signal-Packaging/dp/B0014KOB6Y
They do a variety of devices for different cell systems.

Like most consumer electronics devices, it is not worth it to try to do it yourself.  These guys count every fraction of a penny in producing these products.

It is especially true for this type of device.  Do you have the test equipment to insure compliance?  This device has to be registered with your cellular provider if you want to be legal.