CHAPTER 2 - Conveying Power at Radio Frequency
52
Figure 2.5-14 Current loops charge capacitors further down the line and discharge preceding ones
Figure 2.5-15 Voltage pulse approaches the end of the line
As the end of the line is reached, as in the previous case, there is no voltage across the
inductor to maintain current flow (Figure 2.5-15). The inductor however tries to maintain current
flow into the capacitor and charges it up to E volts (Figure 2.5-16).
Figure 2.5-16 Inductor tries to keep current flowing as the end of the line is reached
This is only temporary however because once the current flow due to the energy stored in the
inductor stops, the capacitor will naturally discharge into the penultimate capacitor, which is at
lower voltage, until the voltages are even and back to E/2 across both capacitors. To do this the
current must flow in the opposite direction to the incident one (Figure 2.5-17). Current loops, with
direction of flow opposite to those created by the incident wave, move back down the transmission
line, creating a reflected voltage of the same amplitude and polarity and a reflected current of same
magnitude and opposite polarity travelling back towards the generator.
E
E/2
I
E/2 E/2
E
E/2
E/2
E
E/2 →E
Conquer Radio Frequency
52 www.cadence.com/go/awr
