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Pulse Doppler radar systems are increasingly being used for airborne maritime surveillance roles, but current models for sea clutter do not incorporate the spectral information required to analyse the detection performance of these systems in the low grazing angle maritime environment. This report uses standard radar sea clutter models, and spectral information from wavetank and open ocean mea- surements to deduce the amplitudes, Doppler frequencies, and bandwidths of the Bragg, whitecap and spike components, which together comprise the sea clutter return.

it is proposed that a hemisphere be used as the standard target when radar cross section measurements must be made of a target on or near a ground plane. These tables enable the radar cross section of any hemisphere whose radius is in the range 0.1 to 10.0 wavelengths to be determined for angles of observation up to 30 from the horizontal. Asymptotic expressions are presented for hemispheres outside the size range of the tables. A sphere is commonly used as the standard target in the calibration of radar cross section measurements because its backscatter cross section is invariant with aspect angle and is readily calculable to any desired order of accuracy. If however, the target undergoing measurement is located on or near a ground plane, complications arise if a sphere is to be used as the standard target because of the additional ray paths introduced between the radar and the sphere by reflections from the ground plane, and because the sphere can couple to itself, thus modifying its scattering characteristics, by other reflections from the ground plane. In general therefore the radar cross section of a sphere above a ground plane is not readily predictable, and will be strongly dependent upon the height of the sphere above the ground plane and the aspect angle. Thus the generally desirable properties of the sphere in isolation are no longer evident.

The biconical corner reflector is a useful device where moderate enhancement of the radar cross section is required. This report uses the principles of physical optics to develop a formula for the radar cross section of an arbitrary biconical corner reflector illuminated at an arbitrary angle of incidence within the confines of the faces of the reflector. Previously published results containing arithmetic and typographical errors for the special case of normal incidence on a symmetrical reflector are corrected. (Author)

This memorandum discusses a technique for the computer generation of range-height-angle coverage charts for radars of arbitrary height. Such charts are useful to provide a qualitative assessment of propagation paths between a radar and an arbitrarily positioned target. Keywords: Electromagnetic wave propagation; Radar targets; Area coverage; Atmospheric refraction; Target angle; Computerized simulation; Refractive index; Ray tracing. Australia.