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The difference between Directional and Omni-Directional Antennas

Looking for an antenna? Find out if a Directional or Omni-Directional antenna best suits your needs.

The difference between Directional and Omni-Directional Antennas

All antennas have a specific use case. In order to determine whether a Directional or an Omni-Directional antenna is best, you need to know the basic functions of both!

An Omni-Directional antenna radiates and receives the RF energy equally, providing a 360 degree radiation pattern which allows connectivity in all directions.

A Directional Antenna has a radius of around 45 to 90 degrees, focusing RF energy in a required direction and limiting connectivity to that particular area. This can help overcome interference and multipath, providing better and more structured coverage.

The diagram below shows Directional and Omni-Directional antennas in use within Wi-Fi AP application.

Directional and Omni-Directional antennas within a WiFi AP application

The application will determine which type of antenna you require

Directional vs. Omni-Directional Antenna is a case-specific choice.

Generally, Omni-Directional antennas are easier to install due to their 360 degree radiation pattern, you can place them anywhere you require. They are compatible with a variety of cellular base stations and usually have lower Gain with more redundancy. For example, a router is able to ‘roam’ around various cells, including any newly built cells when using the antenna, but this comes at a cost. The more cellular base stations involved, the less concentrated the connection will be.

A Directional antenna reduces interference from other directions, with higher throughput, but it is limited to a specific base station capacity. This means that these antennas are very dependant on a cellular tower availability.

The diagram below shows how Directional and Omni-Directional antennas receive cellular base stations.

Directional and Omni-Directional antennas receiving cellular base stations

Some Important Factors to Consider

It is important to note, that higher antenna Gain does not always mean better. For more information on Gain, have a read through our Dive Into Antenna Gain" blog post. A quick example below, shows Omni-Directional antenna application with illustrated lower Gain, in pink, and higher Gain, in black.

As you can see, higher gain of an Omni-Directional antenna reaches further, but does not cover the intended area of houses. Whereas, lower gain antenna does not reach as far, but covers most of the desired housing area.

Omni-Directional antenna gain

Moreover, an Omni-Directional antenna works by having energy lobes pushed in from the top and bottom, and forced out in a doughnut type pattern (as seen in the diagram below). If you continue to push in on the ends of the pink balloon, it will result in a pancake effect with very narrow vertical beamwidth, but with a large horizontal coverage. This type of antenna design can deliver very long communications distances, but has a disadvantage: poor coverage below the antenna (in purple).

The diagram below shows an Omni-Directional antenna (isotropic antenna pattern).

Omni-Directional antenna pattern

However, the higher the Gain of a Directional antenna, the higher the coverage distance, but the effective coverage angle will decrease. For Directional antennas, the RF energy is pushed in a certain direction and little energy is present on the back side of the antenna. The diagram below shows radiation pattern of a Directional antenna.

Directional antenna radiation pattern

A Directional antenna would be the best choice in a point to point application, where all transceivers are fixed. Point to point works by pointing two antennas at each other to achieve a much better connection potential. Since the signal is in more of a cone shape (see diagram above), and only goes in the direction it is pointed at, less people have access to the increased signal, making the application more secure.

Use cases for Omni-Directional and Directional antennas

Omni-Directional antennas would be a great choice for vehicles on the move. For example, campers, RVs and boats that want to receive WiFi from resorts, clubhouses, hotels, campgrounds, restaurants, etc. For more information on Transportation Antennas please read through our "Get onboard with Poynting marine and vehicle antennas" blog post.

Another use case would be providing signal for outdoor ATMs by using an Omni-Directional OMNI-600 Poynting Antenna. See example below.

Omni 600 antenna on outdoor ATM

On the other hand, Directional antennas will help focus the signal more intensely towards a specific location. Here are some situations that make the Directional antenna a prime choice.

  • Broadcasting a hotspot or connecting to a hotspot when you know the location

  • Broadcasting a hotspot or connecting to a hotspot over long distances

  • Point-to-point; Using two antennas to create a strong connection.

Directional antennas are great in 'line-of-sight' applications, such as covering hallways, long corridors, isle structures, etc. However, because the angular coverage is less, you cannot cover large areas. This could be a disadvantage for overall indoor coverage. Directional antennas used indoors typically have lower Gain, and as a result, have a lower front-to-back and front-to-side lobe ratios. This results in less ability to reject or reduce the interference signals. Also, because the antenna arrays have to face in the direction where the coverage is desired, it can make mounting of Directional antennas a challenge.

Wide-band directional antennas would be the best choice when available signals are weak. These antennas are recommended more often than an Omni-Directional antenna as it has double the Gain and it also works with the frequency bands commonly used for 4G LTE.

Construction sites would be a great fit for a wide-band Directional antenna, in order to increase signal capacity in high utilised areas. As the locations of these sites are temporary, they would not usually have a wired internet connection. Construction companies might opt for a broadband internet solution which can be mobile and used at another location when the project is finished. Employees at the construction sites need to be able to send things like construction drawings, timesheets, reports, camera surveillance, inspections and recordings via a secure VPN internet connection. In this instance, they might want to use a router in combination with a Directional antenna such as the XPOL-2 High Gain Cross Polarised LTE MIMO Antenna.

Conclusion: Omni-Directional or Directional antennas?

Omni-Directional antennas are best suited for applications requiring good all-round coverage. They are a good choice for most users as they are easy to install and provide consistent coverage over a broad area, servicing multiple providers.

Directional antennas are good for applications that require the available RF energy to be focused in a particular direction. Since their signal is concentrated in a more narrow field than Omni-Directional antennas, they are able to reach out farther to pull in a more powerful signal. These antennas generally provide amplification for only one provider, so you have to determine the location of the nearest cellular base station. Directional antennas are better suited for people in rural areas where the distance between cellular base stations is much greater than in urban or suburban areas.

Take a look through our range of antennas to suit any need. If you have any questions, please don’t hesitate to contact us via email at help@netxl.com or phone on 0330 043 3000.

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