Bi-static radar speed sensor

In an apparatus, cooperating with a vehicle having forward and rearward portions along a longitudinal axis, for sensing the speed of motion of said vehicle with respect to a ground surface in a forward direction substantially parallel to said longitudinal axis and substantially parallel to said ground surface, said apparatus being of the type including first means for transmitting a probe signal to said ground surface, second means for receiving signals reflected from said ground surface and third means, responsive to signals respectively indicative of said probe signal and said reflected signals for generating a signal indicative of said speed, the improvement wherein:

• said second means comprises at least first and second antennas each of said antennas receiving a portion of said reflected signals, said first antenna having a radiation pattern disposed facing forwardly in a direction substantially parallel to said longitudinal axis and downwardly towards said ground surface at a first angle with respect to said ground surface, said first antenna radiation pattern covering a portion of said ground surface;
• and said second antenna having a radiation pattern disposed facing rearwardly in a direction substantially parallel to said longitudinal axis and downwardly towards said ground surface at a second angle with respect to said ground surface and converging with and said first antenna radiation pattern on said ground surface portion.