Radiation characteristics of an antenna mounted in a car

Handy phone services have come into wide use. Handy phones can now be used almost anywhere such as inside a car. In these cases, the input level to the handset is reduced considerably because of the shielding provided by the car´s body. Moreover the car´s body affects the directivity of the handy phone antenna. Many pattern nulls will probably be introduced. However, up to now, no method is known that can accurately predict the performance of such antennas. This paper examines the possibility of using scale models to predict the antenna performance of handy phones used within cars. To that end we conduct a simple experiment that compares the radiation patterns measured using a one seventh scale model to those output by a commercial simulation program. Some previous reports have examined the effect of car bodies on the performance of handsets used near the car, but not in the car. Measured and calculated directivities are found to agree rather well. This confirms that measured and simulation methods are useful for estimating antenna directivity.