79-GHz LTCC RF-frontend deploying 45 degree linear-polarized vertical parallel-feed antennas

This paper presents a 79-GHz RF-frontend realized in low-temperature co-fired ceramics (LTCC) technology. The frontend is designed for the short range radar (SRR) applications. For the radar antenna, a laminated waveguide (LWG) was chosen as transmission line due to its low conductor loss and a 45◦ linear-polarization was used to reduce interferences. Further, an LWG-based vertically oriented parallel feeding-network helps to keep the antenna main-beam direction constant across the 4 GHz bandwidth. A four-channel SiGe radar transceiver chip was applied to build the frontend. Combing the multiple-input multiple-output concept with virtual antennas, the aperture of the radar was enlarged. To verify theory, the RF-frontend was fabricated and measured with a baseband-board. The radar achieves a range resolution of about 8 cm, a minimum angle resolution of 10° and a field-of-view of 120°. The frontend has a dimension of 23 mm × 30 mm × 1.7 mm and in total 15 layers of ceramic tapes were used. This compact LTCC RF-frontend is suitable for the 79 GHz SRR applications.