HIGH-FREQUENCY (SKY-WAVE) RADAR PERFORMANCE

The expected performance of high-frequency radar has been examined as a function of sunspot cycle, season, and time of day, using recent ITSA techniques. The method of performance assay provides a good basis for both radar design and comparison. A particular set of radar parameters was chosen: PG squared T sigma = 137 db (where P = average power above a watt, G = antenna gain above an isotropic radiator in free space, T = predetection integration time over a second, and sigma = target radar area over a square meter) and a 10- db postintegration signal-to-noise ratio is required. A 5-to-1 frequency band permits effective operation at distances from 500 to 1500 naut mi 95 percent of the time, to 1900 naut mi 80 percent of the time, and to 2000 naut mi 60 percent of the time. The sporadic E effects have been ignored, which makes long-range coverages optimistic. The better coverage long-range limit is generally set by the maximum one-hop distance. Vertical launch angles between 0 and 38 degrees are useful. Performance improvement possibilities have been examined; it is estimated that 20 to 40 db over the postulated 137 db could be achieved.