Measurements and simulation of ionospheric scattering on VHF and UHF radar signals: Channel scattering function

Abstract

[1] The design and operation of transionospheric VHF and UHF radars requires knowledge of amplitude and phase scintillation due to ionospheric scattering. Phase coherence is of particular importance where long coherent integration periods and large bandwidths are required. A thin phase screen, parabolic equation based, Trans-Ionospheric Radio Propagation Simulator (TIRPS) is described. Modeled channel scattering functions (CSFs) are compared to experimental VHF and UHF data derived from the Advanced Research Projects Agency Long-range Tracking and Instrumentation Radar on Kwajalein Island (9.4°N, 166.8°E). TIRPS quantitatively reproduces the experimental results, including the quasi-parabolic profile observed in the measured CSFs under strong turbulence conditions. Variations in the simulated CSF with ionospheric phase screen parameters are also presented. Under conditions of high integrated strength of turbulence (C k L), a low phase spectral index (p = 1), indicating relatively dense small-scale irregularities, produces pronounced range spreading. Conversely, when the spectral index is high (p = 4), indicative of strong focusing/defocusing by large-scale irregularities, there is increased Doppler spreading and, when the outer scale of irregularities is large, a greater likelihood of asymmetry of the CSF about the zero Doppler axis.

A global ionosphere scintillation propagation model for equatorial regions

“…Using an appropriate change of variables (Rino & Fremouw 1977;Rogers 2009), it can be shown that (11) is equivalent to (8) with an additional geometrical factor. As a consequence all the analysis can be done using a 2D geometry (1D phase screens).…”

Measurements and simulation of ionospheric scattering on VHF and UHF radar signals: Coherence times, coherence bandwidths, and S4

“…Studies of scintillation over a two‐way (radar) path are relatively uncommon due to the expensive radar facilities required; but see, for example, papers by Knepp [1983a, 1983b] and Coster et al [1993, 2002] who have addressed the impact of the ionosphere on radar phase‐coherent pulse integration. This paper extends the earlier work by Cannon et al [2006] and a companion paper [ Rogers et al , 2009]. It uses the measurements from the Advanced Research Project Agency (ARPA) Long‐range Tracking and Identification Radar (ALTAIR) radar in association with the Trans‐Ionospheric Radio Propagation Simulator (TIRPS) [ Rogers et al , 2009] to understand the relationships between CT and CB and parameters such as S 4 .…”

“…This paper extends the earlier work by Cannon et al [2006] and a companion paper [ Rogers et al , 2009]. It uses the measurements from the Advanced Research Project Agency (ARPA) Long‐range Tracking and Identification Radar (ALTAIR) radar in association with the Trans‐Ionospheric Radio Propagation Simulator (TIRPS) [ Rogers et al , 2009] to understand the relationships between CT and CB and parameters such as S 4 . In so doing we have been able to further refine the TIRPS model and we gain insight into a number of important issues.…”

Validity of 2‐D electromagnetic approaches to estimate log‐amplitude and phase variances due to 3‐D ionospheric irregularities

“…Above this angular domain, the dimensional reduction introduces an error that is a growing function of | α Z |, reaching ⟨ χ 2 ⟩ 3D /⟨ χ 2 ⟩ 2D ~98 for | α Z | = 90°. Therefore, and as commonly accepted in the literature from qualitative considerations [ Rogers et al ., ], it can be concluded that 2‐D PWE/1‐D MPS numerical scheme can be safely used for equatorial configurations at nadir whenever the dimensional reduction is conducted for α Z = 0°, i.e., along the longitudinal plane ( u , s ) with u across the Earth's magnetic field lines.…”