Investigation of Bent PCB Laminates for Conformal Antennas at 80 GHz

In automotive radar systems, conformal antennas can increase the view angle of a single sensor and improve the performance. However, if PCBs (printed circuit boards) are used, a curved surface or bends are necessary to connect the antenna with the chip. Therefore, this work focuses on a sharp bend as a worst case scenario and investigates angles between 0° and 30° up to 110 GHz for three materials (PTFE and resin-based). For the sake of the measurement, a meander structure is mounted on holders with different bending angles. The properties of a single bend are extracted by creating a cascaded model of the line with discontinuities. The results show that the bending over an edge causes only a phase degradation due to a longer way of the signal. An explanation for that behaviour is found in an arc around the edge.