Keywords: Project Diana antenna.jpg 111 5 MHz Reflective array antenna at Fort Monmouth New Jersey USA used by the US Army Signal Corps 1946 in Project Diana to bounce a radar signal off the Moon It consists of 64 half-wave dipoles in an 8x8 array in front of a flat reflective screen and had a gain of 24 dB and a main lobe beamwidth of about 15° It was driven by a 50 kW modified SCR-271 radar set that produced quarter-second pulses The echoes took about 2 5 seconds to return The antenna could be rotated in azimuth only so the experiment could only be done at moonrise and moonset as the moon passed through the antenna's horizontal beam It was the first demonstration that artificial radio signals could penetrate the ionosphere From http //www army mil/cmh/books/30-17/S_9 htm PD-USGov original upload log page en wikipedia Diana_antenna jpg 2006-09-02 11 58 Mwhite66 299×440×8 120535 bytes <nowiki>Project Diana antenna US Army Signal Corps 1946 http //www army mil/cmh/books/30-17/S_9 htm PD-USGov </nowiki> 1946 in New Jersey Fort Monmouth Antenna towers and masts in the United States United States Army Signal Corps EME communications Array antennas |