Remote electrical tilt (RET) is a base station antenna capability that enables RET operators to alter the direction of their antenna beams remotely. This allows them to adjust their networks without having to move the antennas physically or climb up a cell tower. It is done using electrical equipment, and standards have been established by the Antenna Interface Standard Group (AISG).
An AISG controller is connected to antenna line devices (ALDs) with a smart bias tee and the signal is transmitted up the tower using the feeder line. Normally, the AISG controller is located near or at the base station. It can be integrated into the base station, rack mounted or even hand-held. The ALDs are typically located near or at the antennas. Antenna RET motors, tower-mounted amplifiers, or other RF path equipment can be used for this.
The controller can be connected to the ALDs by using a separate data cable from the ALDs to the controller. This could however add additional fees to tower leases, and many sites therefore use other approaches. As base station radios nowadays have integrated AISG controllers, AISG signal can be injected directly onto the main feeder line. Smart bias tees can therefore be used at the top of the tower to establish a link between ALDs and the feeder line.
The smart bias tee can also be built directly into the antenna. This approach has a number of advantages:
- Antenna can also have AISG connectors for inputs and outputs, allowing flexibility and daisy chaining. Antenna can be installed in different configurations, including connecting a controller that controls several ALDs on a single feeder run.
- As installers don't have to install another directional device, installation errors are reduced and it can never be left out by mistake.
- Tower leasing fees can be reduced as the number of components are reduced.
Have comments? Please share them below.
Share this post