Overview

• University of Manchester models show civilian airport radars emit a combined 2×10^15 watts, detectable up to 200 light-years by facilities like the Green Bank Telescope.
• Focused military radar bursts can appear up to 100 times stronger from certain angles, producing unmistakably artificial signatures.
• Because high-power radar has been in use only since the 1950s, Earth’s current technosignature sphere spans about 75 light-years.
• Simulations mapping signal propagation toward nearby systems such as Barnard’s Star and AU Microscopii illustrate how these emissions vary over time and observer location.
• The authors propose expanding SETI searches to include unintentional emissions and revising spectrum management and radar design to minimize future leakage.