基于混合多层介质的E波段微带-波导过渡设计

Design of an E-band microstrip-to-waveguide transition for mixed multilayer substrates

针对高密度球栅阵列(BGA)封装的片上系统(SOC)芯片在具有波导接口的毫米波雷达中的应用,提出了一种用于E波段混合多层介质的低损耗、强鲁棒性的微带到波导的垂直过渡结构。混合多层介质中的矩形耦合腔由密集排列的金属化过孔形成,通过常规的印刷电路铣削工艺,将耦合腔区域中的电介质完全去除,以减少电介质加载造成的损耗。一个分立的径向线探针通过波导结构件与多层介质板压接,不需要焊接即可实现信号耦合。背靠背测试结果表明,在75~85 GHz频率范围内,所设计过渡结构的回波损耗大于13 dB,单个过渡结构的插入损耗小于0.8 dB。所提出的过渡结构可解决混合多层介质载板中微带电路到波导的转接过渡,且不需要任何复杂的工艺,其性能对多层混合介质的材料参数偏移也不敏感,具有较强的工程适用性。

Aiming at the application of system on chip(SOC)with high density ball grid array(BGA)package used in millimeter wave radar with waveguide interface,a low-loss and robust microstrip-to-waveguide(M2W)vertical transition for mixed multilayer substrates(MMS)at E-band was presented.A rectangular coupling cavity in the MMS was formed with densely arranged metallized vias.The dielectric materials in the region of the coupling cavity was completely removed by simple printed circuit board(PCB)milling process to reduce the loss caused by dielectric loading.A discrete radial-shape probe was attached on top layer of the MMS through the waveguide structure,thus the signal coupling can be realized without soldering.Back-to-back(B2B)measurement shows the return loss is larger than 13 dB,and the insertion loss of each transition is less than 0.8 dB over the 75-85 GHz band.The proposed transition can be used to convert the MMS-based microstrip line to waveguide without any complicated process,and its performance is not sensitive to the deviation of the material characteristics of MMS,therefore,thus the proposed structure exhibits excellent applicability in engineering practice.