Radar observations of the Moon at a wavelength of 8.6 millimeters

Radar reflections from the moon at a wavelength of 8.6 mm were first detected in April 1963 [Lynn et al., 1963a]. All previously reported results have been at wavelengths of 3 cm and longer. Following the initial observations a measurement program was undertaken to determine the distribution of scattering at this frequency. The precision 28-foot antenna at Lincoln Laboratory with a half-power, two-way beamwidth of 3.2 min of arc provided a high degree of angular resolution (approximately one-tenth of the lunar diameter). An available peak power output of only 12 watts made it necessary to use an effective transmitter pulselength of 2.5 sec and a narrow receiver bandwidth requiring great frequency stability of the transmitter. Unlike most equipments used in the lower-frequency lunar observations, the radar provided no resolution in either range or Doppler. The system parameters are summarized in Tables 1 and 2.