Date of Award


Publication Type

Doctoral Thesis

Degree Name



Electrical and Computer Engineering


Applied sciences, Collision avoidance, Radar sensors


Sazzadur Chowdhury




This dissertation presents the architecture of a new MEMS based 77 GHz frequency modulated continuous wave (FMCW) automotive long range radar sensor. The design, modeling, and fabrication of a novel MEMS based TE10 mode Rotman lens. MEMS based Single-pole-triple-throw (SP3T) RF switches and an inset feed type microstrip antenna array that form the core components of the newly developed radar sensor. The novel silicon based Rotman lens exploits the principle of a TE10 mode rectangular waveguide that enabled to realize the lens in silicon using conventional microfabrication technique with a cavity depth of 50 μm and a footprint area to 27 mm x 36.2 mm for 77 GHz operation. The microfabricated Rotman lens replaces the conventional microelectronics based analog or digital beamformers as used in state-of-the-art automotive long range radars to results in a smaller form-factor superior performance less complex low cost radar sensor. The developed Rotman lens has 3 beam ports, 5 array ports, 6 dummy ports and HFSS simulation exhibits better than -2 dB insertion loss and better than -20 dB return loss between the beam ports and the array ports. A MEMS based 77 GHz SP3T cantilever type RF switch with conventional ground connecting bridges (GCB) has been designed, modelled, and fabricated to sequentially switch the FMCW signal among the beam ports of the Rotman lens. A new continuous ground (CG) SP3T switch has been designed and modeled that shows a 4 dB improvement in return loss, 0.5 dB improvement in insertion loss and an isolation improvement of 3.5 dB over the conventional GCB type switch. The fabrication of the CG type switch is in progress. Both the switches have a footprint area of 500 µm x 500 μm. An inset feed type 77 GHz microstrip antenna array has been designed, modelled, and fabricated on a Duroid 5880 substrate using a laser ablation technique. The 12 mm x 35 mm footprint area antenna array consists of 5 sub-arrays with 12 microstrip patches in each of the sub-arrays. HFSS simulation result shows a gain of 18.3 dB, efficiency of 77% and half power beam width of 9°.