Antenna Downtilt: A Practical Overview

June 13, 2019 at 8:00 AM

  

When managing cellular networks with multiple base stations, one of the toughest challenges for operators is mitigating inter-cell interference. As 5G implementation ramps up, this will become increasingly important as service providers look to strengthen networks to increase capacity.

 

To successfully densify, base stations must be able to reuse frequencies within their cellular clusters. This means that operators will need to have firm control over the radiation pattern of each antenna, as radiation sprawl will result in electromagnetic interference and poor quality communications.

 

One of the best ways to stop radiation sprawl is downtilt – a process that directs the antenna’s vertical pattern towards the ground. Downtilt can be accomplished by using these two methods:

 

Mechanical Downtilt:

This is the fastest and easiest way to control an antenna’s pattern. It involves physically adjusting the pole-mounting brackets of an antenna by using a digital level against the back of the antenna for an accurate measurement. The downside of this method is that it will create an effect called pattern blooming, which reduces the signal more at bore sight and less at angles away from bore sight.

 

Electrical Downtilt:

Another way to change an antenna’s radiation pattern is by introducing an electrical phase taper inside of a sector antenna array. Electrical downtilt allows for a uniform reduction in coverage, preventing pattern blooming from happening. There are three types of antennas electrical downtilt antennas: fixed, variable and manual. The values of fixed electrical downtilt antennas cannot be changed after design and factor in the antenna’s elevation beamwidth along with other deployment dynamics. Antennas with variable electrical downtilt can be changed remotely. Manual electrical downtilt antennas are set with a tuning knob during installation, or they can be adjusted by a second tower climb if needed. While electrical downtilt prevents pattern blooming, variable and manual electrical downtilt antennas are usually more expensive and reduce antenna gain.

 

To check out our extensive line of antennas, click here.

 

© L-com, Inc. All Rights Reserved. L-com, Inc., 50 High Street, West Mill, Third Floor, Suite 30, MA 01845