Coupled microstrip and its application to broadband microwave structures
As the most frequently used waveguide type in microwave and millimeter wave integrated circuits, microstrip theory occupies an important position in understanding the behaviour of such structures. In this thesis it is shown that coupled microstrip, through its several degrees of freedom can be used to achieve predictable state of the art performance of active devices such as a multioctave medium power amplifier operating over the 2 - 18 GHz frequency band with +29 dBm saturated output power and 20 percent power added efficiency. Both quasi-static and full wave and analytical techniques are covered for coupled microstrip lines. In depth analysis of edge-coupled multiconductor suspended microstrip with tuning septum, as well as multiconductor broadside coupled lines with position dependent coupling coefficient, are presented. Important relationships between the mechanical dimensions and such parameters as coupling factor and phase velocity are also derived. The technique based on spectral domain analysis uses considerable analytical preprocessing to eliminate the need for the sophisticated computer facilities which would perviously be required to analyze such complex structures. Based on the above mentioned technique, novel broadband planar hybrids, magic-T's and matching structures are proposed and analyzed.