Two modes
Terminal mode: the radar that THAAD batteries use to guide interceptors in the final phase. Forward-based mode: pointed up and out, watching for missile launches over the horizon, cueing other systems. Same hardware, different software, different tilt.
The numbers
X-band (8–10 GHz). Estimated detection range against a baseball-sized RCS: 1,000+ km. Against a missile booster: 4,000+ km. The radar can resolve a warhead from its decoys — the holy grail of missile defence.
Where they live
Japan (Shariki, Kyogamisaki), South Korea (Seongju with THAAD), Israel, Turkey (Kürecik), Qatar, UAE. Each panel costs about $1 B. Each is a strategic asset whose siting decisions make the news.
Limits
A truck-mounted radar with a single panel only sees one direction. You need several to cover an arc. Atmospheric ducting and ionospheric storms degrade it. And once a warhead reaches terminal phase, you have 30 seconds before impact.