59 Novel Hairpin-Line Microstrip Bandpass Filter with 2^nd & 3^rd Spurious Passbands Suppression Available to Purchase

In this paper we present novel wideband quasi fractal geometry for suppression of second and third harmonics in hairpin-line microstrip bandpass filter (HLM-BPF). This new fractal geometry is obtained by modifying Minkowski fractal. HLM-BPFs have two main problems, having narrow passband and spurious bands which are located at the second and third harmonics. The former relates to relatively weak coupling between resonators and the latter relates to the difference between odd and even phase velocities of resonators. By using this novel geometry we could overcome these problems so that the second and third harmonics of fractal filters are suppressed and the bandwidth is increased to 54% of the central frequency. In order to validate the proposed geometry, third-order Chebyshev bandpass filter was designed at 1 GHz with a 25% fractional bandwidth on FR4 substrate. Theoretical and simulated results are presented.