Field distributions in a passenger vehicle

A series of measurements were made in order to determine the field distribution in the interior of a mini-van. These measurements were made in the frequency range 200-1000 MHz, using fields established at 40 V/m and 50 V/m. Both horizontally and vertically polarized fields were established. The resulting fields in the interior of the vehicle were measured at 21 locations. Figure 1 shows the schematic for the measurement. Due to the growing use of cellular phones, it is important to the vehicle manufacturer to understand how the fields generated by these devices will react with the structure of the vehicles in which they will be used. Cellular phones are generally used with an exterior antenna, but in many cases the transmitter is located on the inside of the vehicle. The antenna therefore, acts to excite the resonant cavity that is composed of the vehicle passenger compartment. How the cavity is excited is dependent upon the location of the excitation device. The measurements to be described show how the fields distribute on the interior in the presence of an exterior field illuminating the vehicle from the forward direction. Both horizontal and vertical illumination were used.