What is omnidirectional antenna? - Definition from WhatIs.com


omnidirectional antenna

Part of the Wireless and mobile glossary:

An omnidirectional antenna is a wireless transmitting or receiving antenna that radiates or intercepts radio-frequency (RF) electromagnetic fields equally well in all horizontal directions in a flat, two-dimensional (2D) geometric plane. Omnidirectional antennas are used in most consumer RF wireless devices, including cellular telephone sets and wireless routers.

In theory, a vertically oriented, straight conductor such as a dipole antenna measuring no more than 1/2 wavelength from end-to-end always exhibits omnidirectional properties in a horizontal (azimuth) plane. Multiple collinear (in-line) vertical dipoles also exhibit omnidirectional behavior in the azimuth plane; they can offer improved performance over a single dipole in some applications. If the conductor axis is not oriented vertically, then the antenna radiates and receives equally well in all directions in the plane through which the conductor passes at a right angle. However, this ideal state of affairs exists only in the absence of obstructions or other nearby conducting objects. In practice, surrounding objects (such as the user of a cell phone set or a computer next to a wireless router) distort the radiation and reception pattern.

In the usual context, a so-called omnidirectional antenna does not perform equally well in all possible directions in three-dimensional (3D) space. Such a device, which can exist only in theory but can be approached in practice, is called an isotropic antenna or isotropic radiator.

Antennas that offer enhanced performance in some directions, at the expense of other directions, are called directional antennas or directional radiators. The most common example is the dish antenna used with satellite Internet, satellite television, and space-communications installations. Other examples include the Yagi antenna, quad antenna, billboard antenna, and helical antenna.


Continue reading about omnidirectional antennas:

Omnidirectional Antenna Types

Design of a Planar Omnidirectional Antenna for Wireless Applications

Easy Homemade 2.4 GHz Omni Antenna

Replacing the Wi-Fi Antenna on a Wireless Router

This was last updated in March 2012
Posted by: Margaret Rouse

Related Terms


  • Apple Smart Keyboard

    - Apple's Smart Keyboard is a detachable, full-size, text input device designed for the iPad Pro. Its conductive material means the keyboard never has to be charged, and it can be unfolded to functio... (SearchMobileComputing.com)

  • Apple 3D Touch

    - Apple 3D Touch is a pressure-sensitive feature first included in iPhone 6s and 6s Plus that triggers different actions based on how much force the user puts on the screen. (SearchMobileComputing.com)

  • Apple Live Photos

    - Apple Live Photos, first available on the iPhone 6s, turn pictures into short videos by capturing movement and sound in the seconds before and after a user takes a photo. (SearchMobileComputing.com)


  • Wireless and mobile

    - Terms related to wireless and mobile technology, including definitions about consumer mobile technology devices and communication technologies such as Wi-Fi, WiMAX and LTE.

  • Internet applications

    - This WhatIs.com glossary contains terms related to Internet applications, including definitions about Software as a Service (SaaS) delivery models and words and phrases about web sites, e-commerce ...

Ask a Question. Find an Answer.Powered by ITKnowledgeExchange.com

Ask An IT Question

Get answers from your peers on your most technical challenges

Ask Question

Tech TalkComment



    Contribute to the conversation

    All fields are required. Comments will appear at the bottom of the article.