Radar emissions could reveal the fleet, but submarines still barred the approach

Without airborne early warning, some Type 42 radars had to transmit, exposing a broad indication of the task group's position to electronic surveillance. A radar can be detected well beyond the range at which it identifies its own targets, so emissions created a large locating cue. That offered Argentina useful targeting information but did not solve the approach problem. British submarines patrolled the exclusion-zone approaches, while Argentina had invested more heavily in strike missiles than in the anti-submarine capability needed to clear them.