Substrate integrated waveguide passive circuits

Substrate Integrated Waveguide (SIW) technology is used for the design and implementation of compact, low loss and cost effective systems in the microwave and millimeter frequency range [1]. SIW combines the advantages of planar transmission lines like flexibility and compactness with the advantages of conventional metal waveguides like robustness to interference, low loss and high quality factor. The ability to easily integrate with other components on the same chipset makes SIW suitable for implementation of high performance millimeter wave systems at lower cost [2]. SIW finds its application in realizing various components like power dividers, couplers and six port receivers. This is the main motivation and focus of this project. In order to enhance the performance of SIW structures to possess wideband characteristics with further reduction in device size, study has been done on introducing metamaterials in SIW structures in this project. The aim of this work is to design passive circuits namely power divider, hybrid coupler and six port receiver using SIW technology to operate at 24 GHz center frequency using CST CAD tool. At around 24 GHz, the 3 port SIW power divider has S11 equal to -30dB, S21 and S31 close to -3dB and S32 equal to -16dB. The SIW hybrid coupler has S11 equal to -27dB, S21 equal to -5dB, S31 equal to -3dB and S41 equal to -22dB. Further, SIW power divider and SIW coupler which are the basic building blocks of the six port receiver are integrated to design the six port receiver. After the integration, there is a slight drift in the frequency. At around 24.7 GHz, S11 is equal to -15.4dB and S21 is equal to -11.5dB. S31, S41, S51 and S61 are close to - 6dB. Initial studies on introducing Composite Right Left Handed (CRLH) metamaterial structures of appropriate dimensions in SIW uniform waveguide are attempted in order to study the enhancement in performance and the added advantage of using CRLH in SIW structures. By optimizing the CRLH structure, better performance in terms of wider bandwidth and smaller device size can be achieved. CRLH structures may be introduced in SIW power divider, coupler and six port receivers for compact size and wideband characteristics.Master of Science (Communications Engineering