SYNTHESIS APPROACH FOR UWB FILTERS
The synthesis approach for microwave filters is always highly demanded [1–7] due to its unparalleled high efficiency in systematically determining the overall filter dimensions once the design specifications are given. As discussed in Chapter 3, all the element values for a conventional parallel-coupled line bandpass filter with different orders and ripple levels can be immediately found out from the existing design tables and insertion loss graphs, thus bringing out much convenience for all the designers. Without tedious optimization procedure based on time-consuming full-wave simulation, synthesis approach directly establishes all the element values or parameters in a filter network as a closed-form function of required specifications of a filter. Even though synthesis approach cannot account for frequency dispersion and discontinuities involved in a microwave filter on transmission line topology, it can at least directly determine the initial dimensions of the filter so as not only to significantly reduce the design circles but also to give a clear insight into the working principle of a filter. In this chapter, a direct synthesis approach will be introduced and explained to design a class of UWB bandpass filters with Chebyshev equal-ripple responses in the concerned UWB passband. The MMR-based UWB filters in Chapter 5 are reinvestigated and redesigned using the synthesis method. The objective of this approach is ...