Before revision: A quarter-wave impedance transformer, often written as λ/4 impedance transformer, is a component used in electrical engineering consisting a length of transmission line or waveguide exactly one-quarter of wavelength (λ) long and terminated with some known impedance.
After revision: A quarter-wave impedance transformer, often written as λ/4 impedance transformer, is a transmission line or waveguide used in electrical engineering of length one-quarter of wavelength (λ) and is terminated with some known impedance.