Millimeter-wave characterization of several substrate materials for automotive applications

Automotive radar systems such as collision warning, which are under development are driving the advancement of low cost millimeter-wave materials, and processes. This is especially true of material properties data. These automotive systems operate in the 30-100 GHz range. However, most vendor specifications for substrates give dielectric constant and loss tangent at a frequency of 10 GHz or lower. Several test methods have been developed over the years to obtain this type of data. These methods are compared, and one is used to evaluate LTCC from Ferro Corporation, commercial grade TMM from Rogers Corporation, and reinforced Teflon from Allied Signal at 95 GHz. The test method is described and test data is presented.