EM Simulation of Installed Antenna Performance on Land, Aerial and Maritime Vehicles Frank Weinmann, Peter Knott, Thomas Vaupel Dept. Antenna Technology and Electromagnetic Modelling AEM Fraunhofer Institute for High Frequency Physics and Radar Techniques FHR Wachtberg, Germany frank.weinmann@fhr.fraunhofer.de Abstract—During the design process of modern land, aerial and maritime vehicles, numerous parameters have to be considered already in the planning phase to ensure that the radio, radar and navigation systems on board do not interfere with each other when in operation. Besides, surrounding structures, i.e., the platform itself or its environment, may also affect the performance of the designed antennas. For this reason, the electromagnetic simulation of installed antenna performance is an essential step in the design of antennas on platforms. This paper provides a brief overview of selected EM simulation approaches as well as examples of successful application. I. INTRODUCTION Modern vehicles, aircraft and ships are equipped with a growing number of antennas and sensors for a variety of navigation, localization and communication tasks. Designing the antennas and planning the positions of antennas on a vehicle are difficult tasks as numerous antenna systems compete for the best position in the restricted space available. Contrary, the positioning of an antenna at a specific location can also have an influence on the design of the platform. Electromagnetic (EM) simulation of the installed performance of antennas on platforms is rather challenging because on the one hand the surrounding structures may be very complex in terms of geometry, materials and dimension, and on the other hand the antenna’s performance may severely be degraded in the presence of the platform. Hence, it is not sufficient to study the antenna’s properties in free space, but the influence of the platform must also be considered. In order to get reliable results for the simulated EM properties, advanced simulation tools need to be employed. The following sections provide an overview of the EM simulation tools developed at Fraunhofer FHR as well as examples of successful application of these tools to complex EM simulation tasks. II. EM SIMULATION TOOLS AT FRAUNHOFER FHR Apart from employing commercially available EM simulation software, special tools are developed for simulating scenarios which are too large or too complex for standard treatment. Depending on the type of problem, both full wave and high-frequency methods are used in the design process of an antenna. A. Full wave tools Full wave methods generally aim at solving the EM problem by finding a solution to Maxwell’s equations. As a prerequisite, the scenario must be discretized in an appropriate form (surface or volume discretization with the cell sizes being small as compared to the wavelength), which is one of the main difficulties with these methods. At Fraunhofer FHR an integral formulation based on the Finite Element (FE) Boundary Integral (BI) method combined with the Multilevel Fast Multipole Method (MLFMM) is developed [1]. The BI part is based on the Combined Field Integral Equation (CFIE), which is solved by applying advanced iterative solver techniques. This procedure currently enables the solution of EM problems for frequencies up to approx. 10 GHz on a fighter aircraft (length approx. 500 wavelengths). For larger scenarios, such as antennas on ships or vehicles in an environment, simulations can be performed only at much smaller frequencies, which is the reason for applying asymptotic simulation approaches in such cases. B. High-frequency tools Asymptotic or high-frequency simulation tools can provide a good approximation of EM fields in very large scenarios, i.e., if the dimensions of the relevant structures are much larger than the wavelength. Thus, a ray tracing algorithm based on the well-known Shooting-and-Bouncing-Rays (SBR) [2] is developed at Fraunhofer FHR [3, 4]. The SBR approach is used for finding relevant propagation paths, while the field strengths on these paths are calculated with appropriate Physical Optics (PO) and Physical Theory of Diffraction (PTD) formulations. This method has proved to produce rather accurate results and is most commonly used for RCS predictions of arbitrary large targets. One of the drawbacks of this method is the assumption of a point source and the neglect of the influence of the surrounding environment on the source’s radiation. Thus, this method is restricted to far field antenna problems. III. APPLICATION EXAMPLES Both full wave and high-frequency EM simulation tools have been used successfully to solve recent antenna related problems. As an example, the radiation pattern of platform- integrated antennas has been studied, which clearly showed the 2179 978-1-4673-5317-5/13/$31.00 ©2013 IEEE AP-S 2013