Start here: Bandwidth efficiency is not one universal antenna number; it describes the trade between usable bandwidth, radiation efficiency, size, matching, and the performance criterion chosen.
Why this changes a real station
Electrically small antennas cannot generally deliver wide bandwidth, high efficiency, and tiny size simultaneously without tradeoffs.
What it looks like in practice
A wide 2:1 SWR range looks attractive, but it says nothing by itself about how much accepted power is radiated.
What to do next
State the bandwidth criterion and measure or model efficiency across it rather than rewarding SWR width alone.
Evidence boundary
Keep frequency, reference plane, antenna geometry, losses, measurement method, and safety conditions attached to the conclusion. A match, a DC check, or one field symptom does not prove efficiency or identify the complete RF path.
