In the near future, all newly introduced cars will be equipped with radar based systems enabling safer and more convenient driving. The performance of such systems is directly related with the performance of the antenna front end. Recently, double lens focusing system is proposed. With its high broadside directivity and low scan loss over a wide angular range, it can be considered as a good candidate for future long range radars. In this paper, effects of materials on beam scanning performance of double lens antennas are investigated for millimeter wave radars.