Electro Magnetic Applications, Inc. — Department of Defense SBIR Phase I: AF212-0009

Description

Modeling interactions between antennas, radomes, and the local electromagnetic environment is one of the most challenging CEM problems. The dimensions of the problem span radome surface treatments that can be nanometers thick to the overall size of the radome, which can be meters in dimension. Radomes can be composed of complex materials such as anisotropic layers, metamaterials, and frequency selective surfaces. Further, the thickness of these layers can vary throughout the radome. The antennas behind the radomes range in complexity from simple, single element antennas to complex active electronically scanned arrays. The geometry inside the radome such as avionics, support structures, cables, bulkheads, etc. must also be considered. Energy from the antenna reflects from the radome and the structures inside and behind the radome. This energy can couple into cable harnesses located inside the radome and cause electromagnetic interference to other systems on the aircraft. Radomes must not only meet performance requirements for the underlying antenna and for EMI/EMC but also requirements for the local electromagnetic environment. Radomes must be designed to withstand lightning strikes and to meet P-static requirements. Lightning protection systems such as diverter strips protect the radome by directing current from lightning strikes along conductive paths across the surface of the radome. However, diverter strips can also impact the radiation pattern of the antenna and cause reflections internal to the radome. As aircraft fly through the atmosphere, collisions with rain, snow, fog, dust, and other particles can cause charge to build up on the surface of the aircraft. Application of anti-static coatings to bleed off this static electricity must not adversely impact the performance of the antenna under the radome. There are many factors that must be considered when designing and integrating a military radome. No single simulation product can address all aspects of radome design. Tools exist for simulating antenna performance and the impact of the radome. However, those same tools cannot be used for lightning, P-Static, and cable harness simulations. Other tools exist that can be used for lightning and cable harness analysis, but they lack features for modeling the antennas behind the radomes. EMA proposes to leverage over 30 years of development and validation of the EMA3D Cable product to provide the Air Force with a single simulation tool that can be used for all aspects of the electromagnetic design of complex military radomes. EMA3D Cable is a FDTD solver with an integrated multi-conductor cable harness solver. It has been used to solve HIRF, lightning, P-static, EMP, and EMI problems for numerous military and commercial aircraft, launch systems, and spacecraft. EMA staff have used EMA3D Cable on consulting projects for decades. Knowledge gained from consulting efforts has been incorporated into the software as features and databases of models.