Browse Definitions :
Definition

directional antenna

A directional antenna is a radio-frequency (RF) wireless antenna designed to function more effectively in some directions than in others. The purpose of that directionality is improving transmission and reception of communications and reducing interference. 

In consumer applications, the most common directional antenna is the dish used with satellite Internet and satellite television installations. Other types of directional antennas, such as the Yagi antenna, quad antenna, billboard antenna, and helical antenna, are used in a variety of applications. For example, a Yagi antenna that is mounted outdoors can work well for a wireless Internet connection in a remote area, because the Yagi drastically improves the range compared with a conventional indoor antenna.

For most terrestrial wireless communications purposes, antenna directionality matters only in the azimuth, or horizontal, plane. For satellite and space-communications applications, both the azimuth and elevation (angle above the horizon) are important. A straight, vertically-oriented antenna such as a dipole measuring 1/2 wavelength from end-to-end is omnidirectional in the azimuth plane, meaning that it radiates and receives equally well in all horizontal directions. In any elevation plane, however, a vertical dipole exhibits the most gain parallel to the earth's surface and the least gain directly upward. A horizontally oriented dipole antenna produces more gain off the sides than off the ends in the azimuth plane, so it is bidirectional for terrestrial communications purposes. Horizontal dipole antennas find favor primarily among amateur radio operators.

Directional antennas usually exhibit unidirectional properties. In other words, their maximum gain (increase in efficiency) occurs in a single direction. So-called bidirectional antennas have two high-gain directions, usually oriented opposite to each other in space. An omnidirectional antenna radiates or intercepts radio-frequency (RF) electromagnetic fields equally well in all horizontal directions in a flat, two-dimensional (2D) geometric plane.

 

Continue reading about directional antennas:

Cisco Systems discusses the characteristics of directional antennas versus omnidirectional (nondirectional) antennas.

Engadget describes the construction of a homemade dish antenna for wireless Internet use.

YagiAntenna.net explains how a Yagi works.

This was last updated in February 2012
Networking
  • network traffic

    Network traffic is the amount of data that moves across a network during any given time.

  • dynamic and static

    In general, dynamic means 'energetic, capable of action and/or change, or forceful,' while static means 'stationary or fixed.'

  • MAC address (media access control address)

    A MAC address (media access control address) is a 12-digit hexadecimal number assigned to each device connected to the network.

Security
  • Evil Corp

    Evil Corp is an international cybercrime network that uses malicious software to steal money from victims' bank accounts and to ...

  • Trojan horse

    In computing, a Trojan horse is a program downloaded and installed on a computer that appears harmless, but is, in fact, ...

  • quantum key distribution (QKD)

    Quantum key distribution (QKD) is a secure communication method for exchanging encryption keys only known between shared parties.

CIO
  • green IT (green information technology)

    Green IT (green information technology) is the practice of creating and using environmentally sustainable computing.

  • benchmark

    A benchmark is a standard or point of reference people can use to measure something else.

  • spatial computing

    Spatial computing broadly characterizes the processes and tools used to capture, process and interact with 3D data.

HRSoftware
  • learning experience platform (LXP)

    A learning experience platform (LXP) is an AI-driven peer learning experience platform delivered using software as a service (...

  • talent acquisition

    Talent acquisition is the strategic process employers use to analyze their long-term talent needs in the context of business ...

  • employee retention

    Employee retention is the organizational goal of keeping productive and talented workers and reducing turnover by fostering a ...

Customer Experience
  • BOPIS (buy online, pick up in-store)

    BOPIS (buy online, pick up in-store) is a business model that allows consumers to shop and place orders online and then pick up ...

  • real-time analytics

    Real-time analytics is the use of data and related resources for analysis as soon as it enters the system.

  • database marketing

    Database marketing is a systematic approach to the gathering, consolidation and processing of consumer data.

Close