Directional or Omnidirectional: Which Antenna Is Best?

Posted by Powerful Signal on Sep 13th 2016

Directional and omnidirectional antennas
A directional antenna (left) and an omnidirectional antenna (right).

A cell phone signal booster system includes an amplifier, an outside antenna, and one or more inside antennas. The outside antenna—called the donor antenna—is usually placed on the roof of your building, and communicates with the cell tower.

Like most people, you’re probably not an RF engineer, so it may be difficult to decide which type of antenna is best for your cell signal booster system: Directional or omnidirectional. Let’s examine the basic characteristics of each type of antenna:

Directional antennas

Radiation pattern of a directional antenna
Radiation pattern of a directional (LPDA) antenna.

Directional antennas are designed to be pointed, or focused, in a single direction, somewhat like a flashlight. The light of a flashlight is strongest at the center of the beam and tapers off toward the edges, only illuminating a small area where the flashlight is pointed. Similarly, a directional antenna has a horizontal beam width of about 40 to 80 degrees, depending upon the antenna type. The center of the beam is always the area of strongest signal. A directional antenna also typically has a stronger gain than an omnidirectional antenna.

When should i use a directional antenna?

  • When there is clear line of sight from the antenna to the cell tower.
  • When all required cell towers are off in the same direction.
  • When the distance between the antenna and tower is too far for an omnidirectional antenna to handle.

Omnidirectional antenna characteristics

Radiation pattern of an omnidirectional antenna
Radiation pattern of an omnidirectional antenna.

Omni antennas collect and broadcast signal in a 360-degree pattern, similar to how a light bulb throws light in all directions. Cell signals can bounce off of buildings, landscape, and other objects, and many times it is difficult to determine the direction the signal is coming from. The direction of signal can also change if there are two or more cell towers of nearly equal signal strength in different directions. Omni antennas, with their 360-degree characteristic, are an excellent option for these situations.

When should I use a omni antenna?

  • When there is not a clear line of sight from the antenna to the cell tower.
  • In areas with mountains or dense forests, where the weak outside signal is reflecting off of natural objects.
  • In urban and city environments, where there is strong outside signal reflecting off of buildings.
  • When signal is acquired from cell towers in multiple directions.
  • When your antenna is attached to a moving vehicle.

A common misconception

One of the most common misunderstandings is the belief that an antenna type should be selected based on gain. Gain is the measurement of an antenna’s ability to concentrate the signal it receives and sends. Many people think “the bigger the gain, the better the antenna, and bigger is better,” but this is not correct: Don’t get caught up in the “gain game.” Gain has its place, but it may not be the most important factor in your situation.

Which antenna is the right one for me?

Most of the time—perhaps 90% or even more often—it’s best to use an omni antenna as the donor antenna on your home or building. There are times when directional antennas are best (see above), but omni antennas, overall, do the best job in typical situations.

Call Powerful Signal at 866-912-3444

…or click here to get a free custom quote for your building. We can help you choose the right antenna for your cell phone signal amplifier system.

Learn more about omni and directional antennas from weBoost: