Complex electromagnetic coupling exists between mobile antennas and the vehicles upon which they are mounted. As a consequence of this strong antenna-vehicle interaction, the design of mobile antennas has been determined largely by empirical means requiring a great deal of experimental testing and evaluation. Computer modeling and simulation offers a way to eliminate much of this time consuming process. A technique is presented for modeling the electromagnetic behavior of antennas on vehicles by using a wire-grid to simulate the solid conducting surfaces of a vehicle. Results obtained from the application of this approach to a new class of conformal vehicular antennas are presented. The close agreement between experimental and calculated data demonstrates that the technique can be used to generate design quality information for new mobile antennas.