Conditions affecting the accuracy of speed measurements by low power MM-wave CW Doppler radar

A millimeter-wave radar that measures true ground speed of wheeled vehicles is described. The tradeoffs associated with such a sensor are discussed. The device uses a single-channel receiver, a dual-beam antenna, and a zero-crossing detector to convert the signals reflected from the road surface to an analog DC output voltage proportional to speed. It is shown that the antenna is critical to the sensor design. Theoretical and simulation results are in good agreement with data collected with the sensor. Road tests have shown the device has an error on the order of about 1%