Help Building a Repeater System

We've put together a brief summary of a building cellular repeater system in non technical terms. We explain the components and factors to consider when selecting each part of a system. Remember much of the following are generalizations and simplifications but enough information to select components for a simple system. If you need more help or have questions, please feel free to contact us.

Basic System

building cellular repeater diagram

Basically a cellular repeater system is a system that takes the cellular signal from the outside, amplifies it, then repeats the signal inside.

A simple cellular repeater system consists of 3 basic components:

Outside Antenna
Cellular Repeater / Amplifier
Inside Antenna

Designing A Cellular Repeater System

What a Cellular Repeater System Does

Basically, a cellular repeater system captures the cellular signal using the Outside Antenna. The signal is transferred to the Cellular Repeater / Amplifier through a cable. The signal is then amplified and rebroadcast through the Inside antenna. Sending a cellular signal work in reverse. The signal is captured by the inside antenna and sent to the Cellular Repeater / Amplifier amplified and sent back to the tower via the outside antenna.

Building Signal Booster Installation Video

Here is a great video by Wilson Electronics on installing an In Building Signal Booster.

Outside Antenna

The outside antenna can be omni directional capturing a cellular signal from around it's whip. It can also be a directional antenna sending and receiving the signal in one direction.

Omni Directional Antennas

Omni directional antennas are best for capturing a signal from several towers in the area. For instance, if your repeater system is installation goal it to capture a signal from several service providers (AT&T, Sprint, Verizon, T-Mobile for example) and each service providers tower is in different directions, an omni directional antenna is best.

Directional Antennas

Directional antennas have higher gains because their radiation pattern is focused in one direction. The are best used if your installation requires the strongest signal and your service provider(s) are located in one directions.

Inside Antennas

Just like outside antennas, inside antennas can be omni-directional or directional. How you plan to install an inside antenna will have a bearing on which antenna will work best for your installation.

dome antenna

Ceiling Mount Antennas

Dome Antennas are typically used for ceiling mount antennas. They are directional radiate at 360 degrees horizontally and about 150 degrees vertically. Dual polarity Dome antennas will radiate a small distance upwards as well as downwards. They work best when used in 2 story applications where the antenna is mounted between floors. Panel antennas are typically used as ceiling mounts for taller ceilings like those found in warehouses. Panel antennas radiate at about 60 degrees downward from the ceiling.

panel antenna

Wall Mount Antennas

Panel Antennas are typically used as wall mount antennas. Panel Antennas have higher gains and radiate at a smaller angle than the Dome antenna. Use when you want a more focused signal radiated a longer distance. Dome antennas can also be used as a wall mount antenna for applications requiring wider coverage.

Cellular Amplifiers

The cellular amplifier is the heart of the repeater system. It takes the outside signal, amplifies it then rebroadcasts the signal through the system's inside antenna. A few key factors on amplifiers are:

Gain (db)
Output Power (Watts)
Frequency (MHz)
Oscillation Control

Amplifier Gain

Amplifier and Antennas Amplifier Gain can be used as a relative measure of improved cellular coverage area inside. The higher the gain, the more area is typically covered. If one amplifier has 3db gain more than another amplifier, the amplifier with 3db more gain will cover roughly twice the area. So why don't you just purchase the amplifier with the highest gain? Cost and antenna separation requirements. It's important to note that the higher the gain, the more separation distance required between the inside and outside antenna (Read more in "Oscillation Control" below).

Output Power

Output power of an amplifier can be used as a relative measure of power when communicating with your service provider's tower. Higher power is not necessarily better. The power required is just enough to get the required coverage inside and not negatively effect a service providers tower and knock other customers off (read "Oscillation Control" below). The maximum power allowed with the US is 3 watts. A good cellular amplifier will have oscillation control and will control the power of the amplifier to and from a tower.

Frequency

The cellular amplifier used must match the frequency used by your service provider. Most US cellular service providers use frequencies that are within 800MHz or 1900MHz ranges. Many countries outside the US use 900MHz, 1800MHz and 2100MHz. Sometimes a service provider will use different frequencies for cell phones and mobile internet data. Multiple band amplifiers are available to cover 800MHz and 1900MHz. They are more convenient as they will cover multiple services however, they may not cover as large an area as a single band amplifier.

Oscillation Control

Oscillation occurs when the inside antenna signal contacts the outside antenna. Instead of the outside antenna getting a signal a service providers tower, the two repeater system antennas communicate with each other.

IMPORTANT WARNING: Oscillation control is imperative to your repeater system setup. Cellular amplifiers, if not manufactured and/or installed properly, can interfere with a service provider's towers and adversely effect the service to other users of the tower. It's imperative that a system have oscillation control to avoid this interference.

Tech Tip - Antenna Separation

For a successful installation, it's critical that minimum required separation distance is maintained between the inside and outside antennas. If the two antennas (outside and inside) are too close, oscillation (or feedback) will occur and the Wilson signal booster will then automatically reduce power or shut down completely to protect the cellular network from interference. Always read the install guide, and if you have any questions about required separation distance between antennas, contact us.