The role of meteors in extended-range VHF propagation

It is possible to transmit a continuous signal from point to point by taking advantage of specular reflections from ionization trails formed in the E-region of the ionosphere by meteors of all sizes. A continuous signal is provided whenever such reflections are present in sufficient numbers so that they overlap in time. The factors controlling the degree of overlap are: (1) radio frequency, (2)power (overall circuit sensitivity), and (3) length of path. For best overlap, the individual meteor reflections should be as strong as possible, as numerous as possible, and as long-enduring as possible. If all other parameters are kept the same, lowering the radio frequency increases individual echo strength and duration; raising the power and circuit sensitivity increases not only echo strength and echo duration, but also number of echoes detectable above the noise; and finally, increasing the path length also increases individual-echo duration.