Numerical modeling study of automobiles for EM applications

The use of numerical EM techniques in the design of conformal automobile antennas is increasing. We present a series of theoretical computation and experimental measurements to determine the effect of electrical gaps in an automobile body. We notice that measured and calculated S/sub 11/ values and input impedance are very sensitive to the gaps, especially when the gaps are near the antenna. These gaps change the RF current flow on the surface of the vehicle. The azimuthal gain patterns are also sensitive to the gaps. Wire grid models of an automobile body should include these gaps in order to permit accurate MoM solutions.