The Charged Capacitor

I discuss the Catt, or Contrapuntal, model for the "steady" charged capacitor in Wireless World, sep84, under "Energy Current". “ At any moment, half of the energy in a charged capacitor is moving to the right, and the other half is moving to the left.”

Also I show it in Figure 7 in my 1995 book "Electromagnetics 1" , pub. Westfields Press.

[Additional note planned for p29 of the next (i.e. after 2001) edition of Ivor Catt, Electromagnetics 1, 1995;]

4jan02. Ivor Catt. There is a rudimentary approach to this subject, which does not refer to my earlier dec80 Wireless World article, in the Ramo 1994 edition (but not in the 1984 edition or in the earlier 1944, 1953 versions) of the classic book by Simon Ramo et al., Fields and Waves in Communication Eelctronics, pub Wiley 1965/94, p227;

“5.6 PULSE FORMING LINE .... charging a transmission line of length l to a dc voltage Vo and then connecting to a resistor [R] as shown in Fig 6a .... If .... [load] R is matched to the characteristic impedance, a pulse of height Vo/2 is formed across R for a time 2t, where t is one-way propagation time down the line and the line completely discharged. .... It may at first seem puzzling that voltage across the [load] is not just Vo when the switch is closed, but this is because a travelling wave [back into the source] is excited by the connection .... the wave [into the load] discharges half the voltage initially on the line, and the wave [back into the source] the other half .... ”

[The contrapuntal model for a charged capacitor is evaded by Ramo et al. 10 years after it was published in 1984 in Wireless World, which then had a worldwide circulation of 60,000.] See here .

On page 28 my 1995 book "Electromagnetics 1" , pub. Westfields Press, repeats my discussion of the Reed Relay Pulse Generator touched on by Ramo (above).

Ivor Catt 5jan02

We must give credit to Ramo et al. for being the only text book which mentions that when we discharge a transmission line it delivers half the voltage and twice the length of pulse that we would expect. However, the Ramo idea above is ridiculous. “ .... a travelling wave [back into the source] is excited by the connection ....” Why should a travelling wave be excited in the wrong direction, away from the newly available exit path from the transmission line? I have the answer, which will be proved by The 109 Experiment . The travelling wave was not excited by the connection. It was already reciprocating at the speed of light from end to end of the transmission line, as discussed by me in 1980 .

The above idea, that a “steady charged capacitor” is not steady at all, but contains energy current reciprocating at the speed of light from end to end, is a subset of the Catt idea that energy cannot stand still. It can only travel at the speed of light.

Ivor Catt 16 nov 2010