Ivor Catt's Web
The Catt Anomaly

Better version

Traditionally. when a TEM step (i.e. logic transition from low to high) travels through a vacuum from left to right, guided by two conductors (the signal line and the 0v line), there are four factors which make up the wave;

- electric current in the conductors
- magnetic field, or flux, surrounding the conductors
- electric charge on the surface of the conductors
- electric field, or flux, in the vacuum terminating on the charge.

The key to grasping the anomaly is to concentrate on the electric charge on the bottom conductor. The step advances one foot per nanosecond. Extra negative charge appears on the surface of the bottom conductor to terminate the new lines (tubes) of electric flux which appear between the top (signal) conductor and the bottom conductor.

Since 1982 the question has been: Where does this new charge come from?

Not from the upper conductor, because by definition, displacement current is not the flow of real charge. Not from somewhere to the left, because such charge would have to travel at the speed of light in a vacuum.
Conventional electromagnetic theory says that the drift velocity of electric current is slower than the speed of light.

Signal wire



Animation by Eugen Hockenjos © :)0i 2000


For further information on the Catt Anomaly, see
  • letters in the following issues of Wireless World; aug82, dec82,
    aug83, oct83, dec83, nov84, dec84, jan85, feb85, may85, june85, jul85, aug85
  • The book: The Catt Anomaly (available on this website, click here)