Lunar Radio Echoes

High-power radars at the Naval Research Laboratory have been used to study the reflecting properties of the earth\´s moon. Experimental work over the last six years at frequencies in the 30-mc to 3000-mc band has revealed a lunar surface phenomenon which produces a "highlight." Measurements made at 198 mc have shown that more than 50 per cent of the echo energy is reflected in the first 50 microseconds after the leading edge of a short incident pulse contacts the moon. This fortunate situation permits many interesting astronomical observations and suggests the use of wideband communication signals in a circuit using the moon as a passive relay. Many types of modulation have been successfully passed over the lunar circuit, including amplitude modulation by voice.