What are antonyms for radar?

There isn't a direct antonym for "radar" in the sense of a system that uses radio waves to detect objects. However, you can consider opposites in different contexts:

By function:

* Passive sensing: While radar is active, emitting its own signal, passive sensing relies on detecting existing radiation like light or heat.

* Non-electronic detection: Methods like sonar (using sound waves) or lidar (using light pulses) are alternatives, but not direct antonyms.

By purpose:

* Blindness: If "radar" represents awareness or detection, then "blindness" could be considered an opposite in that context.

By outcome:

* Invisibility: While radar aims to detect, invisibility is the opposite, meaning it's undetectable.

In a figurative sense:

* Ignorance: If "radar" represents being aware of something, then "ignorance" could be considered an opposite.

Ultimately, the best antonym depends on the specific context in which you're using "radar."