Graphical Portrayal of Electromagnetic Radiation

Copyright 2013, David Bryan Wallace

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Warning! The ideas presented in this paper are at odds with Maxwell's laws and may be entirely wrong.

Graphic portrayals of electromagnetic waves in physics textbooks typically [fig. 1] show a directed axis from which an array of vector arrows radiate in two orthogonal planes ( plum ) intersecting in the axis.  The directed axis ( cyan ) represents the path and direction of propagation, vectors in one plane represent electric field ( blue ), while the vectors in the other plane represent magnetic field ( red ).  Both fields vary sinusoidally along the path with the two fields being in phase and, viewed from the source (not from the destination) the magnetic field vectors are 90 degrees clockwise from the electric field vectors.  The deficiencies of this portrayal become apparent when we consider two simple cases of radio wave generation: a simple dipole transmission antenna and a rotating dipole.

The Simple Dipole Transmission Antenna

The simple dipole transmission antenna [fig. 2, animated gif] can be thought of as a piece of straight wire along which electric charge ( blue ) sloshes back and forth.  Charge polarity alternates as does current direction.  The current ( green ) in the wire is zero when the separation of charge is maximal, and the current is maximal when the separation of charge is zero.  Consequently, the generation of electric ( blue ) and magnetic ( red ) fields is 90 degrees out of phase [fig. 3]. This wave pattern is characteristic of plane polarized electromagnetic waves.

Circular Polarization

Circularly polarized electromagnetic waves can be generated by an array of two dipoles skewed 90 degrees and spaced one quarter wavelength, or by a rotating electric dipole (charge dipole, not antenna).  The sense of polarization, or handedness is called right handed (left handed) if the direction of rotation is clockwise (counterclockwise) for an observer looking in the direction of propagation.*  A counter-clockwise rotating dipole produces left circular polarized electromagnetic wave with electric and magnetic field vectors parallel [Fig. 4].  On the other hand, a clockwise rotating dipole produces right circular polarized electromagnetic wave with electric and magnetic field vectors anti-parallel [Fig. 5].

*IEEE Std 149-1979 (R2008), "IEEE Standard Test Procedures for Antennas". Reaffirmed December 10, 2008, Approved December 15, 1977, IEEE-SA Standards Board. Approved October 9, 2003, American National Standards Institute. ISBN 0-471-08032-2. doi:10.1109/IEEESTD.1979.120310, sec. 11.1, p. 61."the sense of polarization, or handedness ... is called right handed (left handed) if the direction of rotation is clockwise (counterclockwise) for an observer looking in the direction of propagation"