Which of the following statements is true regarding the proximity of obstructions to the AN/TPQ-50?

The statement that less than 20 meters can cause performance degradation is correct because the AN/TPQ-50 Firefinder radar system is sensitive to its operational environment, including the presence of obstructions. Being too close to obstructions can interfere with the radar's ability to receive and process signals effectively, leading to reduced accuracy and reliability in target detection and tracking. Therefore, maintaining a distance greater than 20 meters from obstructions is crucial to ensure optimal performance.

The radar's effectiveness relies on a clear line of sight to detect incoming projectiles as well as to avoid reflections and interference caused by nearby structures, trees, or other physical barriers. When these obstructions are within a close range, they can scatter the radar waves or otherwise impede the radar's functioning, resulting in erroneous readings or reduced detection capabilities.