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The orbital element distributions of meteoroids detected during the Harvard Radio Meteor Project, 1968-69 Synoptic Year Program, have been reanalysed to remove selection effects associated with the radar observations. Corrections are made for the observing schedule, antenna beam patterns, the radio diffusion ceiling, speed dependence of ionization production, the flux enhancement due to the Earth's gravity and the probability of encounter with the Earth. These render the eccentricity, aphelion distance, and inclination distributions for meteoroids larger than 10 −4 g (radius ∼200 μm), with orbits that cross the ecliptic near 1 AU.

Abstract.A Fresnel transform technique has been developed at Adelaide to analyse radar meteor echoes detected in the transverse mode. The genesis for this technique was the study of the structure of the scattering ionization immediately behind the head of the trail, in order to deduce the degree of fragmentation of the ablating meteoroid. The technique has been remarkably successful in not only giving insight into the fragmentation of meteoroids, but also revealing other significant features of the trails including diffusion, lateral motion of the trail during formation due to wind drift, and phase of the scattered signal in the vicinity of the head of the trail.A serendipitous outcome of the analysis is the measurement of the speed and deceleration of the meteoroid producing the trail to a precision far exceeding that available from any other method applied to transverse scatter data.Examples of the outcomes of the technique applied to meteor echoes obtained with a 54 MHz narrow beam radar are presented.

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Abstract. In this paper we describe a new technique for measuring the speeds of individual meteors based upon the variation of the phase received in specular reflections from the meteor train prior to the meteoroid reaching .the point of closest approach to the observation site. The technique is characterized by high precision, high yield, and is less subject to selection effects than the techniques used heretofore. About