A radio transmitter takes the information to be communicated and converts it to an electronic signal compatible with the communication medium. Typically this process involves carrier generation, modulation, and power amplification. The signal is then fed by wire, coaxial cable, or waveguide to an antenna that launches it into free space. This chapter covers transmitter configurations and the circuits commonly used in radio transmitters, including oscillators, amplifiers, frequency multipliers, and impedance-matching networks.