On the Development of a High-Frequency Radar Cross Section Model for Mixed Path Ionosphere–Ocean Propagation

Abstract

An analytic high-frequency (HF) radar cross section model for ionosphere-ocean propagation is presented. Based on earlier work, an expression for the first-order received electric field after a single scatter from each of the ionosphere and sea surface is derived and reduced to integral form. The field integrals are taken to the time domain, with the source field being that of a vertically polarized pulsed dipole antenna. Subsequently, the first-order radar cross section for the mixed path mode of ionospheric clutter is developed. The ionosphere reflection coefficient used in the analysis is assumed to be a stochastic process with an associated spectral density function to account for phase variations along the surface associated with nonuniformity of the signal path. Simulation results for the new cross section are also provided. It is shown numerically that the expected magnitude of the ionosphere clutter, under reasonable assumptions, exceeds the dominant first-order ocean clutter for the same apparent range by 50-60 dB. Further, it is spread in Doppler, depending on the ionosphere horizontal velocity and reflecting path nonuniformity. Also, this component can be presented from a certain minimum range, depending on ionosphere virtual height, to the maximum radar range.

Azimuth Resolution Improvement and Target Parameters Inversion for Distributed Shipborne High Frequency Hybrid Sky-Surface Wave Radar

“…The shipborne HFHSSWR not only maintains the capacity of long range over the horizon target detection and wide-area coverage of the HF sky-wave radar, but also retains the stability and long integration time of the HF surface wave radar (HFSWR). It also has the advantage of maneuverability of the shipborne HFSWR, which has an advancement in wide-area surveillance of over-the-horizon targets and ocean environment [4][5][6][7][8][9][10][11][12][13][14][15][16][17]. However, the shipborne HFHSSWR suffers from low azimuth resolution and poor estimation accuracy in azimuth, due to the small array aperture limited by the confined space on a shipborne platform.…”

Bistatic and Stereoscopic Configurations for HF Radar

“…Associated experiments carried out, but several studies concluded that these configurations were optimum only for niche applications. Nevertheless, the concept of augmenting skywave radars with forward-based receiving facilities was resurrected by several groups in the mid-2000s [44,45] and by others more recently [46][47][48][49][50][51]. To date, the modelling studies reported in the open literature have ignored many of the complexities of the skywave leg of the propagation path, though we may anticipate improvements in this area.…”

Ionospheric Clutter Model for HF Sky-Wave Path Propagation with an FMCW Source

“…Based on image theory [13,18], the scattered electric field equations for the backscattering ionospheric clutter at (0, 0, 0) can be written (when ( , , 0) coincides with (0, 0, 0)):…”

“…Walsh et al [12] laid a solid theoretical foundation to describe the scattering of electromagnetic waves from the ocean surface, which has been extended to model the power spectral density of mixed path propagation for pulsed radar [13] and a frequency modulated continuous wave (FMCW) radar [14]. In those models, the ionospheric reflection coefficient (IRC) is assumed as Gaussian function, which may not accord with the ionosphere physical conditions.…”