Meteor echoes at ultra-high frequencies

It is proposed that, at ultra-high frequencies, underdense meteor echoes have an effective scattering length L, which is much less than a Fresnel zone. Consequently, UHF meteoric echoes may be analyzed in terms of Fraunhofer diffraction theory, resulting in a relaxation of the requirement that a meteor trail be perpendicular to the radar line-of-sight before an echo can be received. Formulas for the back-scattered power, time duration, and echo rate are deduced.