Graded dielectric inhomogeneous streamlined radome for airborne applications

A graded dielectric inhomogeneous nosecone radome design with superior electromagnetic (EM) performance characteristics for airborne applications is presented. The radome wall is designed in such a way that the middle layer has the maximum dielectric parameters (dielectric constant and electric loss tangent). On either side of the middle layer, the dielectric parameters of the constituent layers decrease in a graded (or step-wise) manner. This wall configuration facilitates better impedance matching as required for radome applications. The computation of the EM performance parameters of a tangent ogive nosecone radome based on the above-mentioned wall configuration, enclosing an X-band slotted waveguide planar array antenna, is carried out using `geometric optics´ based three-dimensional ray tracing along with the `aperture integration´ method. EM performance analysis shows that the proposed graded inhomogeneous dielectric radome design is a better choice for streamlined airborne radomes compared with the `variable thickness radome´ (VTR) designs based on monolithic half-wave and multilayered radome wall configurations. Furthermore, it excludes the constraints on fabrication that generally occur in the case of streamlined airborne VTRs.