Posted by Admin on June 06, 2015
Radio frequency power amplifiers amplify the transmission of signals such as cellular signals. Also known as cell phone signal boosters and amplifiers, they are used to boost cell phone reception in localized areas using external and internal antennas along with an RF power amplifier.
While they are similar to the large cell towers dotted around the country, they are much smaller, providing better connections to people in one building or vehicle by rebroadcasting the signal into the new space through its antenna and amplifier.
Thanks to technology, more modern systems can help multiple people using the same system at one time, making them useful for commercial buildings as well as residential buildings.
Analog Signal Boosters
These are the most commonly used in North America, using traditional technology to amplify all frequencies from all cell phone carriers using wide band technology. Typically they come with an outdoor antenna, cable and need to be installed.
Smart Signal Boosters
This newer, more modern category uses digital baseband processors that clean signals before redirecting them onwards, giving gains of up to 100 decibels as opposed to analog’s 63-70 decibel range. However, they are typically carrier specific. They are "plug and play", making installation easier and offer improved signals - hence their name of "smart".
No matter which you pick, the market is growing rapidly in America. This is partially due to poor network coverage in rural areas and the abandonment of landlines by many families for the freedom of cellular coverage.
In 2007, 30% of phone users were mobile only, a statistic that has only grown - and increased the demand for cell phone signal boosters immensely. Another gain from cellular repeaters is an increase to the cell phone’s battery life as it requires less battery draining to reach amplifiers that were once a little too far out of range for a good signal.
External Directional Antenna
These are absolutely vital for signal strength gain in the new area, and can be located outside a building to get the best possible signal - if you know where your nearest cell tower is, and which is the best direction to point to it. The larger the antenna, the better the reception, but even a small antenna will provide massive gains on a previously poor reception. Installation can be done DIY or with a professional.
Internal Rebroadcasting antenna
These antennae go inside the building or vehicle, and may be monopole or domed, depending on what you pick. One thing to remember is that cell phones perform best when situated parallel to an antenna due to the polarization of the radio. Even if not parallel, you can still expect significant gains in signal boost if you are in close proximity.
No matter which model you pick, all will come with a signal amplifier that offer gains from 20-50 decibels for cheaper models to over 50 decibels in more expensive models with 70 decibels being standard for commercial applications. Do remember, however, that the logarithmic nature of decibels means that a 30 decibel difference is actually a thousand-fold increase!
The more decibels you need, the more important a well-aligned antenna becomes, since filtering out background noise is more difficult. The math is complicated, but standard GSM channel selected repeaters (those used in cell towers) typically have an output of 2 Watts, while high power repeaters have an output power of 10 Watts.
The repeater needs to be well aligned in order to isolate the signal you want; otherwise you may find yourself stuck in a loop oscillation. In case you get poor isolation, your devices will work, but you will not gain as much as if you were well aligned, and your coverage would be poor.
Ideally, you can improve isolation by adjusting the angles between amplifier and internal antenna to 180 degrees and having a vertical space separation and ensuring that there are no obstacles nearby.
Some cell phone repeaters also have a feature called Interference Cancellation Equipment (ICE) which can be activated to negate internal delays and ensure that there are additional repetitions.
In short, these are not problems you will typically face - they are more or less problems faced by users using commercial grade cell towers and will have a team of engineers to troubleshoot these issues!
Rural areas are the most common area for weak signal complaints. Because of the low amount of homes, carriers may not wish to build cell towers since they are not commercially profitable.
In these cases, a carrier is unlikely to act, putting the onus on cell phone users in rural areas to purchase strong cell phone signal boosters in their homes to obtain a better connection. In the case of flat rural areas, gains can be expected to be massively increased.
Building materials are another traditional enemy of reception, thus requiring RF power amplification. Older buildings can have lead in them, which is a hugely effective signal blocker, and thick concrete and vast amounts of metal can also affect coverage. For example, concrete floors are often laid in metal pans, which effectively block all radio signals. Even in modern buildings, energy efficient materials such as foam, foil and windows can absorb radio signals - effectively preventing them from reaching your cellular device.
Building sizes can also affect your cellular reception. Warehouses, factories and hospitals often suffer issues with cellular reception due to the materials used in their construction and the equipment which they contain. Underground areas of shopping malls and basements are also notorious signal black spots, simply because there are so many physical obstacles blocking and diffusing the signal. In this case, a network of internal antennas will usually fix the problem.
Multipath interference in urban zones is becoming an issue too: although most urban areas suffer few problems when it comes to cellular signals, dead zones can happen. This is when many waves meet at one place. For example, bouncing off buildings into one another - effectively affecting those waves. In this case, directional antennas are enormously helpful in redirecting the path of the waves to stop the signal being destroyed.
Unfortunately, since the waves used by cell phones are too high to reflect of the ionosphere like longer wavelengths, they are not able to diffract as much and do generally require a "line of sight".
Cell phone repeaters are available for all the different frequency bands of the GSM, and can handle different networks including multi-mode GSM and UMTS - but be aware that dual- and tri-band models will cost more. As with all things, the more research you do, the better!
For many years, it was legal to use low-powered cell phone repeating devices in the home and small-scale commercial businesses. On February 20 th, 2013, the FFC released a report that established "network safe" commercial boosters on a licensed spectrum - a compromise between technology manufacturers and wireless operators, a decision that had been coming for years in the making.
The FFC defined two types of repeaters:
Wideband/ Broadband: These amplify all frequencies from cell phone carriers. Manufacturers must limit their gains to 70-72 decibels depending on the range. Due to this limit, these boosters are only useful when the outdoor signal from a cell tower is relatively high.
Carrier specific: These are specific to providers only, and can only boost the signals that those carriers use. Since they do not interfere with other carrier frequencies, they can go as high as 100 decibels, giving them a larger coverage area and better efficiency even with a weak signal.
These rules have been in effect since March 1 st, 2014. More can be read about them on the FCC’s website.