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A closed-form expression for the field produced by a plane wave incident on an infinitely long conducting cylinder, coated with a lossy dielectric of nonuniform thickness, is obtained using perturbation theory. This approximate series solution is later evaluated asymptotically for electrically large cylinder sizes. The scattered fields are interpreted using geometric optics and creeping waves. The fields are calculated using the exact series, the approximate perturbation series, and the high-frequency asymptotic solutions, and compared for different angles of incidence.

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A comparative study of the commonly used methods for the predlctlon of the coverage area due to transmitter operating at the HF band is presented. Those slatlstlcal model-based tools are Ionospheric Communication Analysis and Prediction Program; IONCAP, Ionospheric Communication Enhanced Profile Analysls and Circuit Prediction Program; ICEPAC, Voice of America's VOACAP and ITU's REC 533, and those are illustrated by computing the coverage area of a typical transmitter located at Oxford-England operating at 13399 MHz (HF Band I). Later, those results are compared with the experimental data measured at Istanbul-Turkey for a transmitter located at Oxford-England. Finally, the same problem Is analyzed by the ray-traclng technique using the experimental data. The advantages and the disadvantages of the methods are discussed.