Conference Paper

Low probability of intercept (LPI) radar is regaining attention with the increasingly complex capabilities of electronic support measures (ESM) systems, such as wide-band digitalization and machine-learning classi-fiers. Yet, as of 2025, LPI radar is defined in ANSI/IEEE Standard 686: Radar Terms and Definitions, as "a radar using a coded waveform with low peak transmit power so as to minimize the likelihood of interception by a hostile ES system", which may be misunderstood, and raise questions as what is the maximum power acceptable to be considered LPI? What codification is considered LPI? Are some characteristics really LPI, or just low probability of exploitation (LPE)? In fact, practical LPI radars extend far beyond coded waveforms and low peak transmit power. Frequency agility forces the interceptor to monitor gigahertz of spectrum instantaneously; ultra-wide bandwidth spreads the energy below the thermal noise floor of conventional receivers ; low-sidelobe antennas and power-management reduce the effective isotropic radiated power (EIRP) in the direction of the threat; continuous-wave (CW) operation eliminates the pulse sharp edges that classical ESM processors such as crystal video or instantaneous frequency measurement receivers rely upon. Furthermore, there is debate whether some techniques such as coding waveforms, make the radar less likely to intercept, or just harder to exploit its waveform, i. e., perform deceptive jamming techniques. This paper covers the essentials of LPI radar systems, their characteristics , their waveforms and techniques to identify them. Moreover, we present our developed work to design waveforms for LPI radars, and explore the future trends in this field.