Waveform Diversity is defined in the IEEE Std 868-2008 as Adaptivity of the radar waveform to dynamically optimize the radar performance for the particular scenario and tasks.May also exploit adaptivity in other domains,including the antenna radiation pattern (both on transmit and receive),time domain,frequency domain,coding domain and polarization domain.In other words,modern digital technology now allows us to generate precise,wide-bandwidth radar waveforms,and to vary them adaptively – potentially even on a pulse-by-pulse basis.This opens up many new possibilities,including ultra-low range sidelobe waveforms,orthogonally-coded waveforms for MIMO radar applications,waveforms with spectral nulls to allow co-existence with other transmissions without mutual interference,and so-called target-matched illumination,where a waveform may be matched to the impulse response of a specific target at a specific aspect angle.We may also learn from natural systems such as bats,whose acoustic signals are sophisticated and are used in an intelligent,cognitive manner.The lecture will describe the design of these waveforms and their applications,and the prospects for the future.