An Overview of Recent Advances for the TEMPER Radar Propagation Model

Brief review on PE method application to propagation channel modeling in sea environment

“…Common approaches to the local grazing angles problem are: 1) application of the spectral estimation (SE) [71] technique at each range step to determine the dominant grazing angle; or 2) application of an internal ray-tracing (RT) code to estimate the grazing angles. The RT is used in the case of evaporation duct, whereas SE is better suited for terrain applications; see the discussion on the properties of those methods in Kuttler and Dockery [69], Kuttler and Janaswamy [70], and Dockery et al [72]. The littoral zone includes both variable terrain and ducting and obtaining α for this scenario requires combination of both SE and RT [72,73].…”

“…The RT is used in the case of evaporation duct, whereas SE is better suited for terrain applications; see the discussion on the properties of those methods in Kuttler and Dockery [69], Kuttler and Janaswamy [70], and Dockery et al [72]. The littoral zone includes both variable terrain and ducting and obtaining α for this scenario requires combination of both SE and RT [72,73]. In Barrios [45] the accounting for larger scale roughness (i.e., the terrain irregularities) with the PE method is done (for horizontal polarization and boundary condition for perfectly reflecting surface) by applying a general coordinate transformation [74] that flattens the surface elevations and introduces an additional term, responsible for the terrain effects, in the modified refractive index.…”

“…As it has been mentioned, the sophisticated ray methods (GTD, UTD (Uniform Theory of Diffraction)) and normalmodes methods (or hybrid combinations of them), which overcome the difficulties experienced by the simple ray theory in complex propagation environments (caustics, shadow zones, ducted propagation), are not easy to include in routine calculations. The great flexibility demonstrated by the PE has turned its simplest form (1) into the preferred technique for solving tropospheric propagation problems in a number of thoroughly validated and practically applied radiowave propagation assessment tools as: VTRPE (Variable Terrain Radio Parabolic Equation, solution of (1) based on SSF) [94], PCPEM (PC Parabolic Equation Model, SSF based) [37], TPEM (Terrain Parabolic Equation Model, uses SSF) [45], TER-PEM (TERrain Parabolic Equation Model, successor of PCPEM, combines PE and ray-trace techniques) [95], TEMPER (Tropospheric Electromagnetic Parabolic Equation Routine, based on DMFT) [69], [72], APM (Advanced Propagation Model, hybrid model that uses ray optics and DMFT-based PE) [73], PREDEM (PREdiction of ElectroMagnetic Detection) [96], AREPS (Advanced Refractive Effects Prediction System) [97]. Some of the limitations of this widely spread modeling of the 3D environment with 2D PE are discussed below.…”

“…Ongoing theoretical efforts are mainly directed to: (i) the development of 3D PE models and improving their use friendliness for inclusion in routine calculations; (ii) improvements in the sea surface roughness representation; and (iii) progress in the evaporation duct modeling, particularly with respect to more accurate determination of the height of this type of duct. Further development may be also expected in a PE-based time-dependent propagation modeling as explored in Dockery et al [72]. To improve the environmental input to the PE model, advanced climate analysis techniques are applied; in spite of that, the supply of refractivity data with necessary quality to meet the real-time operational requirements of microwave systems operated, especially, in littoral environments, is still an open issue.…”

Sidelobe clutter modeling for land-based radars in mountainous terrain

“…The propagation model that we use is TEMPER [2]. This model is fast and accurate and gives a two dimensional model of propagation (i.e., range vs. altitude).…”