Reconfigurable Planar Filters文档.pdf

I F S O S C U U E S F E E D A T U lectronically reconfi gurable or R tunable microwave fi lters are at- E tracting more attention for re- search and development because Eof their increasing importance in improving the capability of current and future wireless systems. For instance, emerging ul- trawideband (UWB) technology requires the use of a wide radio spectrum. However, the frequency spectrum as a resource is valuable and limited, so the spectrum is always being used for several purposes, which means it is full of unwanted signals when an operation such as a UWB wireless system is concerned. In this case, existing undesired narrowband radio signals, which vary from place to place