Image: Dipole antenna standing waves animation 461x217x150ms

Description: Animation showing standing waves on a half-wave dipole antenna driven by a sinusoidal voltage VO from a radio transmitter at its resonant frequency. The oscillating voltage pushes the electrons back and forth along the two metal rods that make up the antenna, creating oscillating currents (blue arrows) in the antenna, charging its ends alternately positive (+) and negative (-). Since at this frequency the antenna is a half wavelength (λ/2) long, a sinusoidal wave of voltage or current takes exactly one cycle to make the round trip from one end of the antenna to the other and back, so the reflected waves reinforce each other. The antenna acts like an electronic resonater. Waves of current and voltage reflecting back and forth between the ends of the rods interfere to form standing waves. The waves are shown graphically by bars of color (red for voltage V and blue for current I) whose width at each point is proportional to the amplitude of the wave at that point. There are voltage antinodes (maxima) and current nodes (zero points) at each end, while there is a voltage node and current antinode at the drive point in the center. The large oscillating voltages and currents on the antenna at resonance causes it to radiate maximum radio wave power.
Title: Dipole antenna standing waves animation 461x217x150ms
Credit: Own work
Author: Chetvorno
Usage Terms: Creative Commons Zero, Public Domain Dedication
License: CC0
License Link: http://creativecommons.org/publicdomain/zero/1.0/deed.en
Attribution Required?: No