An ultrasonic wave-front with propagation direction dependent frequency

The use of phased array methods are commonplace in ultrasonic applications, where controlling the variation of the phase between the narrowband emitters in an array facilitates beam steering and focusing. An approach is presented here, whereby all emitters in a 1 dimensional array are pulsed simultaneously, with a controlled bandwidth to emit a 2 dimensional wave. The key result is that one can generate a smooth, continuous wave-front emitted from the array, over a large solid angle, whose frequency varies as a function of angle to the array. Analytic and finite element models created to simulate this phenomena have been validated with experimental results using ultrasonic waves in metal samples. This pulsed approach provides a rapid means of flooding a region of space with a wave-front, whereby any wave that scatters or reflects off a body to detector will have a distinct arrival time and frequency. This is a general wave phenomena with potential applications in radar, sonar and ultrasound.