A new configuration of a miniature microstrip bandpass filter suitable for ISM band

This paper presents a novel structure of a miniature Microstrip Bandpass Filter optimized and validated in the ISM ‘Industrial and Scientific Medical’ band. A Microstrip resonator is used in the suggested filter. Each port has a step impedance feed line that can be used to adapt the filter’s input impedance to the characteristic impedance Z0. The resulting filter is inexpensive and simple to integrate into active and passive circuits. This filter is optimized and validated by using two electromagnetic solvers. The proposed filter is printed on a low cost FR-4 substrate with a dielectric constant εr = 4.4, a thickness h = 1.6 mm, a loss tangent tan (δ) = 0.025 and a metal thickness of t = 0.035 mm. The proposed filter has a bandwidth from 5.05 GHz to 5.97GHz.