[stouset]

This is precisely how modern IADS (Integrated Air Defense Systems) work. You have long-range search radar deep in your territory which can alert to contacts entering your airspace and feed that information to tracking radar located nearer to the front lines. Tracking radar only needs to fire for as long as necessary to get a lock, fire on an aircraft, and allow the radar-guided missile to establish its own lock.

Missile launch sites are located separately from radar sites so they can’t be targeted (since they have no radar emissions themselves) and so that pilots don’t know ahead of time where to look for missile plumes for visual indicators of a launch.

All of these sites are networked so can feed information across a large region and back to a hardened command center far away. Sharing information this way allows minimizing the amount of time between a vulnerable front-line system revealing its location and launching a missile at its target. Tracking radar and missile sites can even wait to become active until a hostile aircraft is over or even past them to defeat wild-weasel style tactics.

Both tracking radar and missile sites are also often mobile so once they’ve disclosed their location by using radar and/or firing a missile, they can quickly move to a new location to avoid retaliatory strikes from anti-radiation missiles and regain the element of surprise.