Optical and diffraction simulation techniques for large multibeam reflector

Abstract

International audienceThe results of geometrical optics modelling and optimization of the modified optical system of RATAN-600 radiotelescope are given. Suggested modifications to the optical system include the introduction of an auxiliary mirror in order to increase focal length, reduce aberrations, and expand the field of view. In this context, diffraction modelling is necessary to determine the beam pattern shape and study the polarization characteristics of the antenna. We used the aperture integration method along with the ray tracing for the calculation of the antenna beam patterns in co- and cross-polarization. Finally, the multilevel fast physical optics (PO) method was adapted for near field and beam pattern simulation of RATAN-600 radio telescope to avoid the GO approximation of the aperture field and take the finite wavelength effects into accoun

Analysis of RATAN-600 radiation patterns in new operation modes using the MLPO algorithm

“…Application of the MPLO algorithm to RATAN-600 radio telescope was considered in [6]. Computation of the RATAN-600 radio telescope power beam patterns at different wavelengths with allowance for diffraction effects in the southern sector with flat-reflector mode [7] are presented for comparison with the MLPO results in Fig.…”

Analysis of the RATAN-600 radiotelescope antenna with a multilevel Physical Optics algorithm

“…Such an extension would be of particular interest for observations of Cosmic Background anisotropies. To minimize wave aberrations while extending the Field of View of the telescope, a longfocus optics has been suggested in the form of a small tertiary quasi-elliptic mirror with double curvature (not a figure of rotation) installed close to the secondary focus [3].…”

“…Analysis of the RATAN-600 S+F antenna system at millimeter-wave frequencies represents a substantial computational challenge, due to its very large electrical dimensions: the main reflector surface area is of about 40 millions of wavelengths for observations conducted at the λ = 8mm wavelength. Until recently, this quasi-optical system has been mainly analyzed using Geometrical Optics (GO)/ray-tracing techniques combined with the aperture integration method [3]. However, GO analysis does not provide sufficient information on near-field diffraction effects and other wave related phenomena, in a context where reflectors are not in their mutual far field regions, as can be inferred from the dimensions given in Figs.…”

Near and far field simulation of RATAN-600 radio telescope antenna using the MLPO algorithm

“…This is especially true when repeated evaluation of the radiation patterns is required for antenna geometry optimization with multiple primary sources, for example, when employing a 10×10 focal array feed. Until recently, this quasi-optical system has been mainly analyzed using Geometrical Optics (GO)/ray-tracing techniques combined with the aperture integration method [1]. For this system, even the use of GO requires substantial computational resources.…”