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Post Info TOPIC: Radio Meteor Detection
Blobrana


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Posts: 131433
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Meteor radio afterglows
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Title: Altitudinal dependence of meteor radio afterglows measured via optical counterparts
Author: K. S. Obenberger, J. M. Holmes, J.D. Dowell, F. K. Schinzel, K. Stovall, E. K. Sutton, G. B. Taylor

Utilizing the all-sky imaging capabilities of the LWA1 radio telescope along with a host of all-sky optical cameras, we have now observed 44 optical meteor counterparts to radio afterglows. Combining these observations we have determined the geographic positions of all 44 afterglows. Comparing the number of radio detections as a function of altitude above sea level to the number of expected bright meteors we find a strong altitudinal dependence characterized by a cutoff below ~ 90 km, below which no radio emission occurs, despite the fact that many of the observed optical meteors penetrated well below this altitude. This cutoff suggests that wave damping from electron collisions is an important factor for the evolution of radio afterglows, which agrees with the hypothesis that the emission is the result of electron plasma wave emission.

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Blobrana


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Posts: 131433
Date:
Radio Meteor Detection
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The detection of meteors by radio is most readily accomplished by a method known as "forward scatter".  This technique usually exploits the existence of a VHF radio transmitter intended for some other purpose (such as radio or TV broadcasting) and which is preferably situated some way beyond the optical horizon so that the direct signal does not desensitise the receiving equipment.  The radio signal reflects mainly from the electrically-conductive meteor trail as it forms and dissipates, causing a brief signal to be heard on or close to the transmitter frequency.  The trails form in the ionosphere (i.e., the upper atmosphere) at a height of about 100 ±20 Km.
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