Anechoic Chamber Simulation Tool using Integrated FDTD and SBR Ray Tracing

Accurate analysis of electromagnetic anechoic chambers is a challenging problem. The geometry is complicated and includes multiple antenna radiators, systems under test (SUT), supporting structures, and absorber. Furthermore the frequency range isextensive, traversing a broad range from 50 MHz to 18 GHz. For the large chamber (264 x 250 x 70 feet) of the Benefield Anechoic Facility (BAF) this means the chamber size in wavelengths varies over a very large range over which different calculationmethods must be applied for good accuracy. Our approach is that for the lower range of frequencies the finite difference time domain (FDTD) method will be used to analyze the entire anechoic chamber. At the higher frequencies shooting ray methods can beused. Both methods will be integrated under a single graphical user interface which will allow user control of the excitation antennas, system under test geometry, and calculation parameters. The graphical user interface will also provide display offields over a variety of surfaces inside the chamber and straightforward comparison with measured fields for validation. The ability to assess the effects of absorber reflection on the illumination of the system under test will be an important capabilityof the proposed software tool.