101.
Why must an antenna range be free of reflections for accurate pattern measurement?
Answer: A
Any reflecting surface acts as a second source whose contribution adds vectorially to the direct one, producing ripples in the measured pattern and badly falsifying the side lobes. Absorber, elevated geometry and time gating are the usual defences. Reflections do not significantly raise receiver noise, do not alter the antenna's terminal impedance at these levels, and cause no heating. Controlling the measurement environment is as much a part of antenna engineering as designing the antenna.
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