By adding a parabolic reflector to the popular HC-SR04 ultrasonic distance sensor the measuring angle is reduced from 15 deg to ~ 2.5 deg. Th range is increased from the specified 4m to ~9m. This project uses an Arduino uno along with the HC-SR04 sensor and 16X2 LCD display. An additional blanking circuit is added to ignore the first reflection from the parabolic dish.

Details of this project are posted at: