Feeders

Antenna Tuning Units – ATU

  • Common types are L-Match (left) and T-Match (right above)
  • Used to match the output impedance of the transmitter (50Ω unbalanced) to the complex impedance presented by the antenna and feeder combined
  • Comprise tunable or switched coils and variable capacitors to provide impedance match
  • Commonly used with random length antennas centre fed with balanced line to provide multiband operation;  when used with balanced line a Balun should be used at the tuner output