UAH

The UAH and UAL are modular shipboard electronic support measures (ESM) threat-detection systems that were retrofitted to Royal Navy OBERON- and VALIANT-class submarines (no longer in service).

The non-scanning antennas (produced by the U.S. company EM Systems) are designed to provide instantaneous 360-degree azimuth coverage with 100 percent probability of intercept. Pulse widths of between 50 nanosec and 100 microsec can be detected, as can signals with vertical,...