What are the Most Common Types of Communication Antennae?

To the untrained eye, an antenna is an antenna is an antenna. But, underneath the surface it's clear there are several different types with as many purposes. Two of the most widely used are directional and omni antennas. 

Both types are critical to wireless internet and are used in different situations. First, let's walk through the difference between an omni and directional antenna. Next, we'll discuss which one is best for your network. 

Omni Antennas

An omni antenna (short for omnidirectional antenna) is a type of antenna designed to send or receive signals in all directions in a horizontal plane, providing a 360-degree coverage. Unlike directional antennas, which focus the signal in a specific direction, omni antennas are ideal for wide coverage areas. 

An omni antenna will generally look like a large stick protruding from the ground. It usually doesn't have the classic "dish" attached that directional antennas have.

Omni antennas transmit their frequency in all directions. Omni is Latin for "all" or "every", so your high school Latin can help you remember how these antennas work! The ability to transmit in all directions has many benefits and a few tradeoffs. 

Benefits of an Omni Antenna

The ability to transmit everywhere at once provides a host of benefits. For one, it requires minimal setup. Omnidirectional antennas simply need to be installed with minimal adjustment. Additionally, they provide broad coverage. The installer doesn't need to know the precise location of recipients, making it perfect for Wi-Fi routers and cell phone communication towers. 

Drawbacks of Omni Antenna

Since omni antennas transmit everywhere at once, they are subject to interference. Since they are looking for signals everywhere, they pick up every signal. This can lead to degradation of service. Plus, omni antennas don't have as long a range as some other antennas. 

Omni Antenna Use Cases

Omni Antennas have tons of uses, one of which is home Wi-Fi. Take a look at your home router, and you'll notice a large stick protruding from its top; that is an omnidirectional antenna. We also mount larger ones into the ground and use them for cellphone reception. You'll notice those all over the place if you're looking for them.

Mounting and Positioning 

One of the drawbacks of omni antennas is that they're subject to interference. Also, they are low range. These drawbacks should be considered when deciding where to place the antenna. So, let's talk about that.

• Avoid Interference: Avoid placing the router next to other electronic devices, if possible. This can create cross talk and degrade the Wi-Fi signal. 

• Minimize Obstructions: Try to keep the router (and its antenna) clear of any obstructions. For example, avoid keeping it in a closet, behind books, or in a cupboard. Place the router in a high area to facilitate signal reception.

• Orientation: To maximize space, it can be tempting to bend your router antenna down. However, this is not a wise decision. The router's primary duty is to point the antenna upwards to maximize reception. Always make sure the router is in a clear area with the antenna pointed toward the sky. 

Directional Antennas

Directional antennas are the "classic" antennas with the large dish and with a stick in the middle. A directional antenna is an antenna designed to focus radio signals in a specific direction, rather than distributing the signal equally in all directions like an omnidirectional antenna. This focused signal allows for greater range and signal strength in the desired direction, making them ideal for point-to-point communication.  

Some directional antennas are called Yagi-Uda antennas (or simply Yagi antennas) after their inventors, Japanese engineers Hidetsugu Yagi and Shintaro Uda. 

Remember older TV shows, where someone would climb a roof to fiddle with an antenna? Then, miraculously, the TV is cleared of static, and everyone is happy. That's a simple example of a directional antenna. 

While all directional antennas work off the same principle, there are several different kinds. Yagi, patch, and parabolic are three of the most common types. With respect to Wi-Fi, the patch antennas are the one you'll encounter the most.

However, even patch antennas have a couple of different variants. For example, iPhones are equipped with PIFA (Planar Inverted F-Antenna) antennas. While variants exist, all these antennas rely on specific positioning to maximize effectiveness.

Benefits of a Directional Antenna

Directional antenna's biggest benefit is its ability to transmit long distances. Properly aligned parabolic antennas can transmit into space and across the planet. Since directional antennas only transmit in a specific direction, they use less resources than an omni antenna. 

Its energy efficiency can save money in the long run. They are perfect for point-to-point communication. Now, let's walk through some of the drawbacks. 

Drawbacks of Directional Antenna

The biggest drawback is that setting up directional antennas can be complicated. They require precise alignment for them to work effectively. (Remember that TV example from earlier.) It's a serious drawback that people have to mess with their antenna to get acceptable reception. 

Directional antennas are also significantly more expensive to set up. They require professional alignment and expertise that other antennas do not need.

Directional Antenna Use Cases

One of the most significant applications of directional antennas is point-to-point communication. ISPs often use directional antennas for long-distance wireless links. This connects Wi-Fi systems in different buildings or areas. 

Directional antennas are also used to provide a greater range of TV channels. DirectTV and other providers often give their customers antennas that point to satellites to provide access to international channels.

Public access Wi-Fi generally uses directional antennas. A specific area, like an airport lounge or a football stadium, will receive a Wi-Fi signal via a directional antenna. 

Another great use is search and rescue operations. Yagi antennas are used in search and rescue operations to track distress signals from emergency beacons. The focused reception helps pinpoint the location of people in distress over a long range.

Mounting and Positioning

Correct installation of directional antennas is critical to their success. Here are a couple guidelines to follow during installation: 

• Pointing and Alignment: First, identify the target location. This will usually be a satellite or another antenna to facilitate point-to-point communication. Use a signal strength tool or built-in diagnostics to ensure the antenna is properly aligned.  

• Height and Elevation: In point-to-point communication, ensure both antennas are elevated to similar heights to maintain a clear line of sight (LOS). There is a possibility you'll need to mount the antenna on a mast to ensure proper elevation. Ensure there are no obstructions to the antenna. 

• Connecting to Access Points or Client Devices: Make sure the access points are on the same setting when connected together. Generally, access points are configured in bridge mode. Ensure proper configuration of security settings, SSID, and channel selection. Remember, each device needs to be attuned to the same frequency. 

Final Thoughts

Antennas may seem like a simple technology, but there’s a lot more than meets the eye. The right antenna can make all the difference for a home Wi-Fi network or long-range point-to-point communication.

Omni antennas are ideal for broad, general coverage and ease of installation. Directional antennas offer precise, long-range communication but require careful setup. Knowing these differences can help you choose the best antenna for your network. They are key to maximizing performance.

Consider factors like interference, alignment, and elevation. They will help your antenna provide the strongest, most reliable signal. With the right approach, both antennas can perform well in many uses.  

Ready to master the fundamentals of wireless networking? Dive into our latest training on Wireless AP Modes and Antenna Types! It's a vital topic for those prepping for CompTIA Network+ exam.