This is a short-range personal radar device that uses any standard sharp IR sensor along with a servo and PIC microcontroller for control. The overall budget may be less than $30 and can be built in a few hours.

IR radar can sense obstacles in range of 4 to 5.5cm distance depending on IR proximity sensors used. It scans 90º wide areas. So it really can make parking easy - well radar scanner has to be protected somehow from rough environment. Well cars are not the only place where it can be used. Radar can be eyes of mobile robot.

IR Radar is controlled by PIC18F452 microcontroller which controls servo motor scanner, reads IR proximity sensor and displays radar information on specially oriented LEDs. Cool project to experiment with.