What You Need to Consider When Purchasing Antennas

 

When buying an antenna there several factors that go into finding the right solution for your network. Without proper consideration, you will not achieve the desired connectivity, which can result in a loss of time and money.

The basic function of an antenna is to take a signal traveling through a cable and convert it to a signal that can travel through the air. The most common applications for antennas are Wi-Fi/WLAN networks, the “Internet of Things” (IoT), and in public safety/first responder systems.

Since there are many different types of antennas, these are a few of the major items to consider before you buy an antenna:

  • What is the application?
  • What frequency do you need?
  • Is there a certain gain or square footage of coverage you need?
  • Do you want coverage everywhere, or in at a specific point?
  • Which connector types do you need?

Here are a few of the most common questions to help you understand which antenna works best for your application.

 

What kinds of antennas are there?

The differentiating factor in antennas is how they are sending their signal. Either the signal is radiating out in every direction, which is called omnidirectional, or there is a reflective surface to focus the signal in a specific direction, which is called directional.

Depending on your primary application there are ceiling, panel, Log Periodic/Yagi, fixed omni, and rubber duck antennas. These antennas operate at different frequencies and gains depending on whether they are radiating signals in omnidirectional or directional reach.

Rubber Duck 

Rubber duck antennas are relatively small and flexible antennas that send and receive signals in an omnidirectional pattern. These antennas are mounted directly to equipment through a variety of coaxial connections. For most at-home applications, these antennas are used in Bluetooth and WLAN systems. In terms of more commercial purposes, rubber duck antennas are used in Long Range Radio (LoRA) networks like Machine-to-Machine (M2M) communications and the Internet of things (IoT).

 Rubber Duck Antenna

 

 

Omnidirectional

These antennas are used in multipoint systems where a wide range of coverage is necessary. Public safety, homeland security, mobile, and Wi-Fi applications would be prime examples of these antennas used in wide range coverage. Omnidirectional antennas are seen mounted to the wall of an equipment enclosure or mounted to a mast. The most common coaxial connection on these antennas is an N-series female. In terms of construction, these antennas are made from UV-stable fiberglass to weather extreme environments. Some also have vented end caps with drain holes to prevent moisture from collecting inside the antenna.

Omnidirectional Antenna

 

 

Ceiling Mount 

Ceiling mount antennas are omnidirectional antennas made for in-building wireless networks to distribute Cellular and Wi-Fi signals for LPWAN, IoT, M2M networks. These are multi-band antennas, operating between 2.4GHz to 5 GHz, which eliminates the need for installing multiple antennas for each frequency. They easily mount through a hole in a solid or suspended ceiling. 

Ceiling Mount

 

 

Log Periodic 

Log Periodic are directional antennas. Their main use is to be mounted on outdoor masts to operate between 2.3 GHz and 6.5 GHz in point-to-point Distributed Antenna Systems (DAS). Since they are used in outdoor installations, the antenna has a UV-stable fiberglass radome to ensure operation in all weather conditions.

Log Periodic

 

 

Directional Panel 

Directional panel antennas are unique in that there are two separate dipole antennas within the housing. One of the N-female ports is meant for vertically polarized signals, and the other for horizontally polarized signals. This polarization diversity makes directional panel antennas ideal for office environments, public hotspots, and industrial/warehouse settings. 

Directional Panel

 

 

What is the frequency range of an antenna?

Frequency in antenna signals is measured in megahertz (MHz) and gigahertz (GHz). Most antennas operate from 860MHz up to 5.8GHz.

Most omnidirectional and directional antennas are dual-band and can operate within 2.4GHz-5.8GHz frequencies. Most rubber duck antennas operate at 900MHz or 2.4GHz, but there are some that are dual (2.4/5.8GHz), or even tri-band (2.4GHz/4.9GHz/5.8GHz).

 

How is the signal strength of an antenna measured?

The gain is the signal strength being emitted from an antenna. It is measured in decibels relative to an isotropic radiator (dBi). The higher the dBi rating, the further the signal is sent on a horizontal plane. The lower the dBi rating, the further the signal is sent on a vertical plane.

Typically, omnidirectional antennas have a lower dBi since they are used to send/receive at 360 degrees. Directional antennas are operating at a higher dBi to send signals further in a horizontal direction.

To give an idea of the relation to dBi and range: a 2.5 dBi omnidirectional antenna can send a signal up to 300ft, whereas a directional Log Periodic antenna at 8 dBi can send a signal up to 1500ft. Keep in mind these maximum distances are within a clear line of sight between antennas.

 

What connectors are used?

The most common connector types for Wi-Fi antennas are N-series, TNC, Reverse Polarity TNC (RP-TNC), SMA, and Reverse Polarity SMA (RP-SMA). In some cases, you may need a coaxial adapter to go from the existing cable line to an antenna, or a lead cable will connect the antenna to a coaxial cable.  

 

If you have further questions or need help finding the right antenna for your network, please feel free to call our inside sales team at 1-833-519-0294.