Cell phone signal boosters, also called amplifiers or repeaters, work by capturing a weak cell signal outside the home, office, car, boat, warehouse, etc, bring it inside, amplify it, and redistribute it. The most popular products on the market contain four main components: the outside antenna, the amplifier (booster / repeater), the inside antenna, and the cabling to connect everything.
The Outside Antenna
The outside antenna can be omni-directional (If the signal to enter from all directions) or directional (it works best when the time directly to a cell tower). The advantage of omni-directional antenna is that it is easy to install and pick up / radiate signals through 360 degrees horizontally. They are ideal for reception and transmission to multiple towers for various airlines. They want as high as you can fit where the signal is stronger. A few drawbacks of the omni-directional antennas: 1) its gain is typically lessthan directional antennas. 2) They are more prone to other RF interference. TheCellphone-Mate CM100-Sis a good example of a popular omni-directional outdoor antenna.
The benefit to directional antennas (Yagi antennas) is that they typically provide more signal gain (power) than omni-directional antennas. They are also less prone to other RF interference. Because they provide more gain, the tower can typically be much further away than is acceptable for an omni-directional antenna. The Wilson 304411 Wide Band Yagi is a good example of a popular directional outdoor antenna.
The Amplifier
Just about every amplifier (or booster) will have two values that basically define it. The first is "band". Most amplifiers are classified as single band or dual band. With the exception of iDEN (Nextel), single band refers to either 850 MHz or 1900 MHz, meaning that the amplifier only boosts one of those two frequency ranges. Dual band on the other hand will Stretch both frequency ranges. Surely there are reasons to buy a band signal booster, are dual-band booster and more compatible with almost all carriers.
The second value is to win and almost a signal amplifier, this specification published. Without too technical win, as the ratio between input and output defined. As used for electrical power, in decibel or dB is measured. dB figures are derived from a relatively simplelogarithmic function; however all you need to know is that every increase in 3 dB doubles the power.
10 dB = gain of 10
13 dB = gain of 20
16 dB = gain of 40
19 dB = gain of 80
20 dB = gain of 100
30 dB = gain of 1,000
40 dB = gain of 10,000
50 dB = gain of 100,000
60 dB = gain of 1,000,000
If you have been shopping around for a cell phone signal booster then you have probably come across these numbers and were not sure exactly what they meant. Now, hopefully you have a better understanding.
When searching for an amplifier for your particular application, please reference the following:
20 dB - Automobile, Boat - 4ft. antenna separation or direct connect
30 dB - Automobile, Boat - 5ft. antenna separation or direct connect
40-45 dB - Large Auto, RV, Large Boat - 6ft. to 20ft. antenna separation
50 dB - Small Home, Townhouse, Office - 40ft. to 60ft. antenna separation
55 dB - Medium Home, Office - 50ft. to 70ft. antenna separation
60+ dB - Large Home, Office, Warehouse - 70+ft. antenna separation
Please keep in mind that this table represents general rules of thumb and the recommended applications and distances may vary by manufacturer. Antenna separation is very important and should not be overlooked when choosing or designing your system. Antenna separation is the straight line distance (in 3 dimensions) from the outside antenna to the inside antenna. In practice, these distances can be somewhat shorter than the rule-of-thumb distances listed above due to ceilings, walls, fireplaces, metal roofs, brick fireplaces, etc. blocking or inhibiting a straight-line signal path. The rule of thumb antenna separation distances are to keep your amplifier from going to oscillation. In the audio world, this is analogous to getting a microphone too close to a speaker and producing feedback.
The Inside Antenna
Inside antennas, just like outside antennas, come in different shapes and sizes, serve different purposed and can be omni-directional or directional. A lot of the products from Wireless Extenders (Wi-Ex) have a small omni-directional antenna attached to the amplifier itself. While this makes installation fairly simple, the unit must become part of your home décor as it must be installed in a central location and will be visible. Most in-building products from manufacturers such as Cellphone-Mate, Digital Antenna, and Wilson Electronics will have a separately mounted internal antenna. This may sometimes make them more difficult to install, but having a separate indoor antenna allows for the most flexibility when choosing a central coverage point. The most popular antenna for providing omni-directional internal coverage is the ceiling-mounted dome antenna, such as the Cellphone-Mate, Inc. CM222. They even make low-profile dome antennas and even dome antennas which resemble light fixtures, which are less obtrusive mesh well with each unit.
antennas inside may depend as well. Wall-panel antennas provide direct coverage is generally 90-120 ° broadcasting. While the cover is completely in front of a directional antenna, they usually offer more useful than an antenna dome. With this said, the panel antennas are ideal for large, but a little 'small rooms or hallways. They are also useful if you are not able to comply fully with the antennaSeparation requirements. If the internal directional antenna must be in the opposite direction the external antenna, it is more likely to be in a position with a lower than recommended by antenna.
Wiring
The connectors and cables are used for external antenna to the amplifier, and connect the internal antenna at the end, play a crucial role in how to run your system. Depending on the product, different types of cables and connectorsused. Some of the Wi-Ex and Wilson Electronics products use standard RG6 or RG59 75 Ohm coax. This is the same coax used for your cable TV or satellite system. While this type of cabling is less expensive, there are some drawbacks. For cellular and PCS frequencies, on average, RG6 will lose 6-10 dB of signal per 100ft. Depending on the actual length of cable you use, this can sometimes provide more signal loss than the outside antenna provides in gain. Remember, you want your amplifier to receive the highest level of signal possible. For this reason, it is recommended that runs using RG6 should be no longer than 50 or 60 ft. For most other in-building cell phone signal boosters LMR-400 50 Ohm Coax is the standard. In comparison, while LMR-400 is more expensive and thicker, it only loses about 3-6 dB per 100 ft for cellular and PCS frequencies respectively.
Based on this, LMR-400 can be run further than RG6 before there is a decrease in system performance. For all three-piece systems (outside antenna, amplifier, inside antenna) it is recommended the amplifier be installed as close to the external antenna as possible, using the shortest cable possible. Ex. If the external antenna is installed on a roof, it is recommended the amplifier be installed in the attic as opposed to the basement. The shorter the cable length between the external antenna and the amplifier, the better. Remember that there is no separation requirement between the antennas and the amplifier, only between the antennas.
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