Abstract

In this thesis we investigate substrate integrated waveguides and their application as a slotted waveguide antenna array. The standard slotted waveguide antenna is designed following Elliot's modified design procedure. Elliot's modified design procedure not only takes into account the effects of mutual coupling from the neighboring slots in the array but also the internal higher order modes that are scattered off adjacent slots. The antenna is then converted to a slotted substrate integrated waveguide antenna by carefully placing two rows of metallic via holes to simulate the sidewalls of the rectangular waveguide. The size and location of the via holes are calculated such that they contain the electromagnetic fields inside the substrate integrated waveguide with negligible leakage loss and that the substrate integrated waveguide has the same propagation constant and characteristic impedance as its equivalent rectangular waveguide. Integrating the waveguide into a substrate allows the entire circuit to be fabricated within the substrate and eliminates the need for complicated transitions that link a rectangular waveguide to a planar circuit. The antenna is fed by a 50] shielded stripline. The stripline is shielded by two rows of via holes placed symmetrically on each side of the trace of the stripline. The transition is composed of a single via hole that links the shielded stripline to the substrate integrated waveguide. Back-to-back transitions between a shielded stripline and a substrate integrated waveguide are designed and simulated for three different frequency bands; C band, Ku band & Ka band. The bandwidth of the transitions ranged from 20-35% in all cases. A back-to-back transition was fabricated for the C-band. The fabrication was done by hand using electrical tape for the stripline inner conductor and screws as the via holes. The bandwidth of the measured results show a smaller bandwidth compared to the simulated results. This disparity is due to the imperfections associated with fabricating the transition by hand. A uniform antenna array of 8 slots is designed and simulated with the feed network. A good radiation pattern with sidelobes 14dB below the main beam is observed. The antenna has an impedance bandwidth of 1GHz at the operating frequency of 15GHz.