Planar microwave filters with reconfigurable or enhanced characteristics

This thesis presents two frequency switchable micro strip line filters. It also presents a third filter that has the potential for frequency and bandwidth reconfiguration. All of these filters are reconfigured using an optically activated silicon switch. This method of tuning is very simple, cheap, and effective. Three new, fixed frequency, filters were also developed as a bi-product of the research presented in this thesis. These filters are smaller than their predecessors, or conventional counterparts. Two Metallodielectric Electromagnetic BandGap (MEBG) low-pass filters, number amongst the new filter designs. These low-pass filters offer a sharper rate of cut-off than is associated with the conventional stepped-impedance filter. They also provide a deep, broad, and well defined stop-band. A miniatursed triangular patch band-pass filter is also presented. This work develops on research by Hong, Lancaster, et al. Design equations and/or modelling aids are presented for each of the new filter structures. On occasions these modelling aids take the form of a lumped-element equivalent circuit together with a series of polynomial equations for determining the element values. Modelling aids, of this nature, are presented for the cymbal resonator band-pass filter. The study into frequency tuneable filters led to an investigation of a particular conduct polymer and the production of a tutorial on dielectric measurement.