Antenna Matching Network
Key to understanding PI networks is the circulating current ---- its the same current in both capacitors, but you get to pick the capacitors.







simulate this circuit &ndash; Schematic created using CircuitLab

Pi networks with equal caps are intended to work with equal Zsource and Zload.

Pi networks with 1:5 ratio of caps will produce 5:1 voltage ratios, and thus 25:1 impedance ratios. Some vacuum tube ham transmitter output matching, or general purpose antenna-tuning boxes, use these extreme capacitor ratios.

If you have 1,000 volt plate and 1 amp (nominally 1,000 ohms) in vacuum tube TRIODE, to match to 50 ohm antenna, that 20:1 ratio comes from 4.5:1 cap ratios.