)
Must be a stealth variant? Black is used on the B-2 bomber and other stealth aircraft to aid in nighttime (and in a weird way, daytime as well) stealth.
Low-probability-of-intercept radar features are also very (perhaps even more) important, and include:
Power management and high duty cycle, meaning the transmitter is on most of the time. (long integration times)
Wide bandwidth (or Ultra-wideband)
Frequency Agility, and frequency selection
Advanced/irregular scan patterns
Coded pulses (coherent detection)
High processing gain
Low sidelobe antennas