Integrated antennas and antenna arrays for wireless computer board-to-board communication

This thesis, as part of the Collaborative Research Center Highly Adaptive Energy-Efficient Computing (HAEC), addresses passive beam-switching networks for the frequency range of 150 GHz to 200 GHz. Multiple possible candidates are theoretically investigated and evaluated. The most suitable choice, the Butler matrix (BM), is further designed and fabricated. This network itself only requires passive components, the switching part is moved to the active frontend circuits. It is achieved by switching on and off the frontends at the individual ports. The theoretical model of a BM is rather simple. The main challenge is to find a design that is suitable for fabrication and achieves a bandwidth of at least 30 GHz. The designs to be fabricated are demanding in terms of fabrication technology. Accuracy and required resolution are the toughest requirements. Additionally, rather complex structures in terms of geometry also require a very flexible technology regarding allowed topologies. Having suitable technologies available, the fabricated designs demonstrate the feasibility of the BM approach to achieve beam-switching. Furthermore it is shown that an accurate knowledge of the material’s characteristics is required to achieve valid simulation results. This also applies to technology properties like surface roughness or used metals. Besides the BM, antenna elements are also investigated. Among them are on-chip antennas, which are fabricated in the same technology as the active circuits in another project of HAEC. Because of the low achieved antenna gain, antennas based on technology similar to the one used for the BMs are also designed. Based on the fabricated BM designs and the designed antennas it is possible to design a complete antenna array that has four distinct beams. Furthermore, eight copies of the BM can be cascaded to design an array that has 16 distinct beams in two spatial dimensions.