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Scattering and absorption analysis of radomes using the Method of Equivalent Dipole Moments (MEDM)

Submitter: Majid Naeem
Description: In radio astronomical applications, it may be essential to accurately evaluate the electromagnetic scattering and power dissipation losses of nearby dielectric objects, such as radomes. However, the numerical analysis becomes a burdensome task for most commercially available computational electromagnetic tools when the dielectric becomes thin, complex shaped, and electrically large.

To mitigate these problems, we propose to employ high-resolution basis functions for accurate modeling of electromagnetic scattering from dielectric objects. Application of these basis functions significantly eases the computational burden of generating the on- and off-diagonal elements of the moment matrix. This method has been hybridized with the Characteristic Basis Function Method (CBFM) and the Adaptive Cross Approximation (ACA) algorithm to reduce both the size and generation time of the moment matrix equation. Furthermore, the proposed method is not only fast and memory efficient but it also generates the accurate solution of scattering problems associated with complex-shaped, thin and electrically large objects.

The method has been used to simulate a curved radome (relative permittivity of the radome material= 6, radius= 2λ, thickness= 0.36λ and arc length= 1.6λ) with a dipole array placed underneath (see picture). As a result of beam scanning at an angle of 45 degrees, both the amplitude and the beam pointing direction are distorted (see picture) in the azimuthal direction. Conclusively, a radome can have detrimental effect on the radiation pattern of the antenna, and must be taken into account during the electromagnetic design phase of the antenna system.
Copyright: ASTRON, Chalmers University
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