Minimization and optimization in the performance of dual-band BPF by using e-shape microstrip structure

E-shaped microstrip structure — with open stub at the midpoint of the microstrip line-is used in designing filter. In this work, the design consists of two filters (filter I and filter II) with two structures (structure1 and structure2). Bandpass filters with dual-band operation are offered and compared with dual-band ones as two groups of various structures or two coupling paths. The sizes of the new filter are greatly minimized. Filter I is compact having an area of 31.37 mm × 9.0125 mm (structure1) and 31.37 mm × 25 mm (structure2) as its dielectric constant used is 2.65 and its thickness is 0.8 mm. Filters II have an area of 19.38 mm × 5.96 mm (structure 1) and 19.38 mm × 10.77 mm (structure 2) as its dielectric constant is 10.2 and its thickness of 1.27 mm. These filters designed to reduce passband insertion losses and high frequency selectivity.