Originally designed for use in military applications to deter enemy radar, electromagnetic absorbing materials and the technologies with which they are often packaged have advanced considerably. Absorbers have now found use in countless applications—from reducing capacitive coupling between an integrated circuit and heat sink to attenuating common mode currents along a trace or cable. In particular, automotive technologies have improved significantly, with such features as collision avoidance, lane-changing assist, and automatic parking becoming integrated into platforms by nearly every major automobile manufacturer.
Assist features utilize a number of different systems to provide additional feedback to the driver. These include GPS, lidar (light detection and ranging), vehicle-to-vehicle communication, and radar (radio detection and ranging). Use of radar systems in vehicles is already prevalent, with many automotive manufacturers relying on radar units for environment object detection. Although 24 GHz systems have been widely used for mid-range detection systems, the use of 77 GHz in mid- and long-range radar units is becoming commonplace in automotive applications. Operation at these frequencies presents designers with new challenges in combating such issues as false positives and interference from surrounding structures, as well as transmitter and receiver antenna crosstalk.