Abstract :
A re-evaluation and analysis of previously published and recently accumulated metropolitan area man-made noise data in the 200 to 500 Mc/s frequency range have been performed. Journal publications and organization reports have been collected and evaluated to obtain expressions for the frequency and distance dependence of radio noise in the vicinity of industrial centers in the United States, Europe, and the Near East. Unpublished results of noise studies conducted by several investigators in the United States were included to supplement the published data. For a typical metropolitan area, three welldefined noise zones have been identified which may be called Central, Suburban, and Very Quiet. For the innermost Central zone, a further subdivision into Urban and Suburban I zones may be justifiable. Least squares approximations curves have been fitted to the noise power data for the frequency interval 200 to 500 Mc/s. The dependence of noise power Pn upon frequency and distance from a city has been represented by a quadratic function of the form: Pn = ¿1 + ¿2 (d -k 1) + ¿3 (d - k2)2 where ¿i = di + bi f. A least squares fit of this polynomial to the experimental data leads to the following equation for noise power Pn in dBm/kc, in terms of frequency f in Mc/s and distance d in miles: Pn = -109-1.71.10-2 f - [0.442-7.72.10-4f][d-2.5] -[1.62.10-2 + 3.45.10-5 f][d - 2.5]2 Manuscript received December 23, 1964. The author is with Aerospace Corp., San Bernardino, Calif.
