# High Frequency Em Scattering by Non-Uniform Open Waveguide Cavities Containing an Interior Obstacle

## Abstract

An analysis of the high frequency (HF) electromagnetic scattering by an open waveguide cavity containing a complex interior obstacle is of interest in scattered field and electromagnetic coupling predictions. A typical cavity-obstacle geometry is shown in Figure 1; this geometry is illuminated by an external source. The interior walls of the cavity are assumed to be perfectly conducting but may contain a thin material coating. The HF scattering by the configuration in Figure 1 is analyzed here primarily for the case when the observation point lies on the same side of the scattering geometry as the source, and for incidence and scattering angles within about 75° from the axis of the waveguide at the open front end. Outside of this region the scattering by external features of the cavity are generally more dominant than the scattering from the cavity interior. The method of analysis described here is based on a hybrid combination of HF ray/beam techniques, or modal techniques (mostly for cavities built up by connecting separable waveguide sections), with other methods. The HF techniques, or the modal techniques, are used to track the fields coupled into the waveguide cavity; whereas, other (numerical or experimental) methods are required in general to deal with the effect of the complex interior obstacle.

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