Abstract: A microwave generating and receiving module generates and transmits a microwave signal which is reflected by a moving target and received back by the module. The module comprises a disc-form Baritt diode BD1 or Gunn diode acting as both oscillator and mixer and forming part of microstrip circuitry and signal processing circuitry which processes the reflected signal to extract relevant target information. The signal processing circuitry can be physically displaced from the module and connected to it by a coaxial line. By operating the diode in the diplex mode the requisite target information can be provided for with a compact construction.