Abstract: There is provided an indirect frequency synthesizer in the millimeter wave frequency range of 36 to 38.6 GHz. The synthesizer comprises a high performance frequency translation loop for operation in the microwave frequency range and contains a voltage-controlled oscillator, an automatic loop gain correction system and a sophisticated lock search system. The frequency translation loop is operable under a variety of conditions (temperature etc.) and overcomes the considerable difficulties which exist in this frequency range such as maintenance of constant optimum loop parameters, thus making it possible to utilize the entire frequency tuning range of the millimeter wave oscillator. As a result, the synthesizer has very satisfactory characteristics as regards noise and spurious frequencies products.