The list of units
Radar Artillery are highly advanced stand-off attack units. The radar allow them to see up to two squares distant, regardless of blocking terrain, and fire that far as well. Radar Artillery has no attack or defense value, so it should be protected by an escort.
A city must have aluminum in its Strategic Resource box to build radar artillery.
Modern radar has had two major impacts on field artillery. The first is that it can accurately 'trace' fire from enemy artillery back to their firing location. The second is to better aim their own artillery to return fire more quickly and accurately. While increasing the technical sophistication of indirect fire weapons (including the support personnel required to maintain such high tech devices), it has also increased their flexibility. Radar has enabled the precise targeting of enemies at any time of day, in any weather condition.