There are many types of Antennas used in WiFi for both indoor and outdoor use and each vendor has its own set of naming conventions. There are even disagreements on how many types really are. Some say there are only two types (Omni directional and Directional) others categorize them as three types (Omni directional, Semi -directional, Highly-directional). All these different type antennas are meant for meeting a specific WiFi distance and coverage requirement. In this blog I will try to explain the different types and their functions.

In a wireless system, an antenna offers Gain, Direction and Polarity or polarization. Gain is the quantity of increase in power that an antenna adds to a radio frequency (RF) signal defined as a measure of rise in power. Direction is the shape of the radiation pattern and is measured in degrees and are called beamwidths.

Before jumping into antenna types, we need to understand an important coverage concept. All antennas provide coverage in both horizontal and vertical planes and based on the antenna type the coverage pattern will be different, as shown in the pictures below.

Lets, first talk about the most common antenna type we come across most of the time. Omni-directional antenna ( also called rubber duck antenna). Omni here mean “all” (God is Omni-present) so this antenna type provides simultaneous coverage in all directions (Theoretically 360 degree in bagel shape). These are mostly deployed in indoor locations up on the ceilings, though they can also be deployed outdoor, on walls and floors based on the location, coverage and requirements. Most modern omni-directional antennas are dual-band offering a combination of either 2.5GHz+5GHz or 5GHz+5GHz frequency bands. This antenna type by default provides point-to-multipoint connectivity. We can use a high-gain omnidirectional antennas to increase horizontal coverage (thus reducing vertical coverage).

Omni-directional Antenna Coverage pattern

Semi-directional antennas (Yagi, Patch and Panel Antennas fall under this category) provide less coverage than omnidirectional antennas (Less than 360 degree). you may see these types on antennas in large campuses, stadiums, auditoriums, retail stores and warehouses. These antenna types are built for both indoor and outdoor use. They can provide directional coverage for long halls or corridors and can also be used to bridge signals between two campus buildings (Short Distance)

Semi-directional Antenna Coverage pattern

Highly-directional antennas (Grid and Parabolic Antennas fall under this category) are designed for sending signals over long distances in a point-to-point or point-to-multipoint configurations. They are for outdoor use only and are installed on towers or a roof of a building. They can survive in harsh weather and can withstand wind, rain or snow.

Then we also have Sector antennas which are in the class of their own. They are highly-directional antennas providing a coverage area resembling a Pie shape. The “Sector” here pertains to an area covered by a single slice of pizza as shown in the picture below. Each slice is a “Sector”

These antenna are useful in situations where we may want to provide coverage to a specific areas. All cell towers use Sector antennas.

So based on our individual needs, we can determine the right antenna types for our use.