Do you mean (a) ultrasonic rangefinding or (b) radar as in radio frequencies?
Radar sends out a strong RF burst, then switches to receiver mode, waits for echoes, and paints them on a scope. To show a panoramic view, the transmitter sends bursts in a directional sweep, with the display screen rotating the echo traces in sync.
If you transmit rf bursts you may get the attention of the FCC and the authorities. You must avoid using frequencies which are in regulated areas of the spectrum. You will probably need a license to use experimental bands of the spectrum.
I think I've heard there are rangefinders which use light to do what radar does.
Also there are radar guns.