A new type of continuous wave radar for the observation of meteor trails

In order to determine ionospheric winds from meteor trails observations, one needs a sensitive radar operating near 30 MHz which can provide a precise localization of the target as well as detect slow target motions. Since, at these frequencies, very short pulses and directional antennas are both impractical, a CW bistatic radar was designed in which direction of arrival, distance, and Doppler measurements are all affected by means of phase comparisons. The precisions obtained are of the order of 0.2 degree, 300 meters, and 1 meter per second, respectively, for an S/N ratio of 25 dB. This was done using three receiving antennas for the angle measurements, three frequencies for the distance measurement, a vertically polarized link to transmit the direct ground wave, and cancelling the backward feedthrough of the transmitting antenna. Experimental results are displayed on a panel, from which they can be read directly.