Meteor observations using radar imaging techniques and norm-constrained Capon method

Multifrequency and multireceiver techniques were employed simultaneously to examine the meteor echoes for the first time. A high-power-large-aperture radar−the Middle and Upper (MU) atmosphere radar (34.85^oN, 136.10° E) was used in observation, with the radar beam directed to the geographic north and at 51° zenith. Receiving was done using 20 receivers and 5 carrier frequencies (46.250, 46.375, 46.500, 46.625, 46.750 ​MHz) for executing angular and range imaging of the meteor echoes, respectively. In addition to the conventional Capon and Fourier imaging methods, a norm-constrained Capon algorithm was also employed to improve the imaging results. Both meteor head echoes and long-duration range spread trail echoes (RSTEs, also known as non-specular meteor echoes) were observed simultaneously. It is demonstrated that range imaging is capable of resolving the evolution of RSTEs in the radar volume clearly, in which the branched RSTEs could be evidence of meteoroid fragmentation. On the other hand, angular imaging with single point of raw data (0.015s time resolution) can identify the multiple echo centers of meteor head echoes, which is also related to meteoroid fragmentation.