Radome Electromagnetic Theory and Design

Chapter 5Scattering from Infinite Cylinders

Large radomes are assembled due to fabrication and mechanical considerations from many panels connected together with metallic or dielectric beams, in contrast to small- and medium-sized radomes, which are planar or conformal and made from one piece. The panels are made of thin membranes or sandwiches, which are optimized for minimum transmission loss over the operational frequency band of the radome, as explained in Chapters 2 and 3. The beams introduce scattering effects that degrade the overall electromagnetic performance of the antenna enclosed in the radome, in addition to the transmission losses through the panels. This chapter will describe various numerical methods to compute the scattering effect from a dielectric, conductive and a heterogeneous beam (dielectric beam with conductive strips) with arbitrary cross section, for orthogonal polarizations and for oblique incident angles. The scattering from a beam can be characterized by its scattering pattern and the induced field ratio (IFR) introduced by [1, 2]. The IFR is defined as the ratio of the forward scattered far-field to the hypothetical far-field radiated in the forward direction by a 2D aperture with a width equal to the optical shadow of the beam on the incident wavefront. The IFR depends on polarization, such that IFR_e is related to TM incident wave and IFR_h is related to TE incident wave. The total scattering effect from an array of beams in front of the enclosed ...