The first driver to respond to an event on the road brakes, the person behind, due to reaction time, brakes a fraction of a second later and has to brake a little harder to avoid hitting the person in front, the person behind them has to brake harder still, and somewhere down the
backward wave the traffic comes to a complete halt.
On the other hand,
backward wave seem to be more suppressed by input feed line.
Carlile examined both theoretically and experimentally the surface wave mode for the constant azimuthal variation (n = 1) and reported that this mode is a
backward wave [14].
The superposition of the forward and
backward wave localizes the SP by forming a standing wave pattern.
It shows that the normalized phase velocity of the novel helix SWS is lower than that of the conventional helix SWS, which shows that the novel structure has lower working voltage, and thus the risk of
backward wave oscillation may be reduced.
Barroso, "Retrieval approach for determination of forward and
backward wave impedances of bianisotropic metamaterials," Progress In Electromagnetics Research, Vol.
1,2) Such isolators must use absorbers to suppress the
backward wave propagation, even though they present a broad bandwidth.
Activities have included efforts at the Army's Harry Diamond Laboratories, working on
backward wave oscillators, traveling wave tubes and vircators; at the Naval Research Laboratory, with klystrons, gyrotrons, cyclotron autoresonance masers and free-electron lasers; and at the Air Force Weapons Laboratory on vircators and magnetically insulated transmission-line oscillators (MILO).
Arrows indicate forward wave and
backward wave inside each layer.
To suppress
backward wave oscillation and reflection oscillation, two concentrated attenuators made of Carburized porous beryllium oxide with relative permittivity and high loss tangent of 6.
When the chirality parameter is greater than the square root of the product of permittivity and permeability, the
backward wave will occur at one of the two circularly polarized eigenwaves [5,6].
