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Repeater FAQ

Wireless Signal Amplifiers, AKA "Repeaters", can be a great solution for many cell phone and mobile broadband users who are experiencing signal strength issues, but they are also the cause of more confusion than any other product we sell. This page isn't meant to be an authoritative white paper, but should serve to help clear up many of the common questions that we answer every day via phone, chat and email. If you have questions about repeaters that aren't answered here, we encourage you to contact us and we'll be happy to help you!



a small home repeater setup

What is a repeater?
A repeater is a wireless amplifier system that does not require a direct connection to cellular devices such as phones and modems. For cellular devices that do not have an antenna port or situations where signal needs to be boosted to multiple devices, a repeater system is the best way to improve signal strength. (If you only need to boost signal to one device and it does have and antenna port, a directly connected antenna - along with a direct connect amplifier if the signal is very poor - is your best choice.)

What are the basic components of a repeater setup?
A repeater system involves 3 basic components: an amplifier and two antennas. One antenna (preferably mounted outdoors) draws the signal in and connects to the amplifier, which boosts the signal; the second antenna, connected to the other side of the amplifier, then rebroadcasts the boosted signal. Multiple cellular devices can then benefit from the boosted signal at once.

When should a repeater be used?
If your cellular device does not have an antenna port, or if you need to boost the signal to multiple cellular devices at the same time, a repeater will be your best option to improve signal strength. Remember that repeaters work best when there IS signal available to boost - repeaters cannot create signal out of nothing, so if you are in a location that truly has NO signal at all, a repeater will not help you. If you are hoping to use a repeater to improve signal in a stationary location (home, office, etc), we strongly encourage doing a site survey before investing in any signal boosting equipment so that you can confirm whether better signal is available in your area AND that better performance results from better signal.

Who should NOT use a repeater?
A repeater is not appropriate for everyone. If any of the following conditions apply to you, a repeater is likely NOT your best option:
  • You have NO signal at all inside or nearby the building or vehicle (a repeater will not create a signal out of nothing; there needs to be at least some signal available to boost.)
  • You only need to boost signal to ONE device, and it DOES have an antenna port (in these cases, a directly connected antenna - along with a direct connect amplifier if the signal is very poor - is your best choice.)


What factors should I take into consideration before selecting a repeater system?
The following are questions we encourage potential customers to consider before selecting a repeater:
  • What networks/frequencies are your cell phones/aircards operating on? Different equipment may be necessary for 3G vs 4G, for example.
  • How many devices are you trying to boost signal to?
  • If you're only trying to boost the signal to one device, does it have an antenna port?
  • Are you looking for an in-vehicle or stationary solution (or both?)
  • Are you able/willing to mount an antenna to the exterior of your vehicle/building?
  • Do you need a directional receiving antenna or an omni-directional antenna?
  • How large of an area are you hoping to boost signal to?
  • If this is for a stationary application, have you completed the site survey to confirm that better signal is available in your area and that better performance results from increased signal?
  • Do you have enough room to separate the receiving and transmitting antennas (for the repeaters that require separation)?


How many devices can a repeater boost the signal to at once?
The number of phones/aircards that can benefit from a repeater depends varies depending on the model. Cradle signal boosters will only boost the signal to the device in the cradle. Vehicle repeater kits are typically best for 1-3 phones/modems, and larger amplifiers do not have a maximum and can boost the signal to as many devices as signal permits (the weaker the "starting" signal, the fewer phones can benefit).

Can a repeater boost the signal to devices operating on different networks simultaneously (e.g. a Sprint phone and a Verizon aircard)?
Yes, as long as the carriers in question all operate on frequencies that are supported by your repeater (most amplifiers work for a variety of frequencies, but you need to double check what frequencies your provider is using in your area). Keep in mind that different carriers are likely to be broadcasting from different towers, so you may not see the same signal increase on devices from different carriers - for example, if you are trying to boost the signal to both a Sprint phone and a Verizon phone, the repeater may provide a bigger boost to one simply because that carrier's tower is closer.

What is the difference between all the different repeaters?
There are a variety of repeater systems available to accommodate the wide variety of needs of different users. The amplifiers themselves can vary in regards to power output, wattage (the power available to connect to the cell tower), and gain (the amount of range you'll get from the repeater); there are also a wide variety of options available for the receiving and rebroadcasting antennas (directional vs omnidirectional, etc). You can find the technical specifications of each amplifier and repeater kit sold by 3Gstore within its product description, and we also recommend looking at the "This Product is Best For..." section located at the top of each product description to help you determine if the product is appropriate for your needs.

What is the difference between a "vehicle-class" and a "building-class" amplifier/repeater?
Firstly, under the regulations the FCC passed for cellular amplifiers on May 1, 2014, it is ILLEGAL to use a "building-class" amplifier/repeater in a mobile/vehicle application. A "vehicle-class" repeater is designed to provide a boost to a smaller area and by design doesn't require much antenna separation. Conversely, "building-class" repeaters have higher gain ratings that relate to how much indoor coverage range/area they will provide, and by design, require more antenna separation. A "vehicle-class" repeater is not likely to be your best choice if you're looking for something for a home/office/permanent location and are typically only recommended for in-vehicle use, but some "building-class" repeater CAN be used in certain in-vehicle applications (for example, a large RV with enough space to allow for antenna separation).

What other regulations does the FCC have on cellular amplifiers?
  • Amplifiers manufactured PRIOR to May 1st, 2014 may no longer be sold
  • Amplifiers must be sold in complete kits that include cabling and antennas
  • Amplifiers must be designed to limit interference and automatically shut down when necessary
  • The packaging must include a warning label to consumers
  • Users must register their amplifiers with their cellular provider
  • Amplifiers can only be a maximum of 1 watt (previous versions were 3 watts)


  • How big of an area can a repeater boost the signal to?
    This is both the most common question and the hardest to answer, as there are many factors that influence the size of an area that a repeater can cover. It is impossible to guarantee exactly how large an area a repeater will provide boosted signal to, but the following are some of the factors that effect a repeater's range:
    • Signal: The worse the "donor signal" (the un-amplified signal) is at the location, the smaller the boosted area
    • Gain: The higher the gain rating on the amplifier (you can view this in the specs), the more area it can cover. A 6db increase in gain results in double the coverage area, so a 62db amp could cover twice the area that a 55db amp would cover.
    • Power: The power capabilities of the amplifier itself also affect the range, because a lower-power amplifier won't be able to pull in as strong a signal as a higher-powered one. Your devices will need to be much closer to the 400mw SignalBoost Mobile Pro, for example, than they would if you were using one of the more powerful repeaters.
    • Transmit Antenna: Some interior transmit antennas are capable of covering larger areas than others.
    • Layout/Floorplan: A repeater used in one large open room will boost the signal to a larger area than if it were used in an office building with walls between each room, and different construction materials will impact the repeater's signal differently (there is a big difference between a drywall wall and one made of metal).
    The "Fast Facts" section at the top of each repeater's product description on 3Gstore includes an estimate of how much area the amplifier can cover. These are just estimates (it's not possible to guarantee coverage area since so many factors affect it) but they will give you an idea of what to expect.

    Why do most repeaters require separation between the two antennas?
    Most repeater systems have a minimum requirement for the distance between the inside and outside antennas in order to prevent oscillation. The repeater will not work if the antennas are not separated far enough, so it is very important to read the product details and/or instruction manual before purchasing a repeater - if you will not have enough room in your application for the required separation, that amplifier/kit is not going to work for you. Higher powered amplifiers typically require more separation between the antennas. Separation can be either horizontal or vertical (in other words, if you mount the external antenna 20' in the air outside, that should be sufficient separation for a repeater that recommends 20' of separation between the two antennas).

    Will a repeater interfere with any of my other electronics (cordless phones, routers, etc)?
    No, a repeater will not cause any interference with other electronic devices.

    What is a "Site Survey" and why does 3Gstore recommend that I do one?
    A "site survey" involves comparing your signal strength and performance (data speeds or call quality) in different locations to determine a) if better signal is available at your location, and b) if improving your signal will result in better performance. Performing a site survey is highly recommended for anyone considering purchasing signal boosting equipment for a stationary location (for travelers, a site survey is obviously not possible since you won't be able to run tests at every location you'll ever be going to). Not every location is the same so it is important to determine whether there is enough usable signal available. If the signal is too poor (worse than -108db RSSI) or too strong (typically better than -80db RSSI), the repeater may not work properly. Performing a site survey does not take much time or effort and can save you a lot of time, energy, and money by helping you determine whether signal boosting equipment will improve your signal and performance BEFORE making a purchase. Click here to read more about site surveys.
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