Lunar radio-reflection properties at decameter wavelengths

A series of lunar radio-reflection experiments has been conducted at the Naval Research Laboratory over a wavelength span between 11 and 22 meters. The measurements made during this first monostatic pulsed radar study of the moon at decameter wavelengths suggest that a wavelength dependence exists in the scattering properties of the lunar surface. Radar cross-section measurements of the moon are reported for several wavelengths, and a composite lunar echo representing the integrated contributions of several hundred individual echoes is presented. These measurements extend to decameter wavelengths the hypothesis that at radio frequencies the moon displays a central highlight that contracts and brightens with increasing wavelength. Possible ionospheric effects were also included in this investigation, and the results indicate that, whereas the earth-moon path frequently is subject to as much as 4 degrees of ionospheric bending, little attenuation due to ionospheric absorption is experienced.