Frequency converter circuit for a radar-based measuring device, said device being used to determine the distance (d) in relation to a measurement object or to determine its velocity, said circuit comprising: - a bipolar or FET transistor with ∘ a base or gate connection, ∘ an emitter or drain connection serving as a frequency connection, and ∘ a collector or source connection serving as a signal connection, said connection serving as a signal input for a low-frequency input signal (Txi), - at least a first emission antenna connected to the signal connection, said antenna being designed to generate a high-frequency emitting signal (Tx h), - an oscillating circuit, which is connected to the frequency connection, - at least a first reception antenna to receive a high-frequency reception signal (Rx h), - at least a first non-linear semi-conductor component, which is arranged between the first reception antenna and a signal ground, - a second emission antenna connected to the base or gate connection, wherein said antenna is designed to generate the high-frequency emitting signal (Tx h), - a second reception antenna designed to receive the high-frequency reception signal (Rx h), the second reception antenna being connected to a signal output for a low-frequency evaluation signal (Rx l), and - a second non-linear semi-conductor component arranged between the second reception antenna and the signal ground, wherein an antenna arrangement is provided, which decouples the high-frequency emitting signal (Tx h) in the direction of the measurement object and/or which couples the high-frequency reception signal (Rx h) reflected by the measurement object at least into the first reception antenna, and wherein the first reception antenna is connected to the signal output for the low-frequency evaluation signal (Rx l). - a bipolar or FET transistor with ∘ a base or gate connection, ∘ an emitter or drain connection serving as a frequency connection, and ∘ a collector or source connection serving as a signal connection, said connection serving as a signal input for a low-frequency input signal (Txi), ∘ a base or gate connection, ∘ an emitter or drain connection serving as a frequency connection, and ∘ a collector or source connection serving as a signal connection, said connection serving as a signal input for a low-frequency input signal (Txi), - at least a first emission antenna connected to the signal connection, said antenna being designed to generate a high-frequency emitting signal (Tx h), - an oscillating circuit, which is connected to the frequency connection, - at least a first reception antenna to receive a high-frequency reception signal (Rx h), - at least a first non-linear semi-conductor component, which is arranged between the first reception antenna and a signal ground, - a second emission antenna connected to the base or gate connection, wherein said antenna is designed to generate the high-frequency emitting signal (Tx h), - a second reception antenna designed to receive the high-frequency reception signal (Rx h), the second reception antenna being connected to a signal output for a low-frequency evaluation signal (Rx l), and - a second non-linear semi-conductor component arranged between the second reception antenna and the signal ground, wherein an antenna arrangement is provided, which decouples the high-frequency emitting signal (Tx h) in the direction of the measurement object and/or which couples the high-frequency reception signal (Rx h) reflected by the measurement object at least into the first reception antenna, and wherein the first reception antenna is connected to the signal output for the low-frequency evaluation signal (Rx l).