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 ). <EOS>