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In this paper, the design and realization of optimized microstrip quarter wave coupled bandpass filters for 1.8-6.2 and 5.8-10.2 GHz frequency bands with improved harmonic rejection are discussed with the center frequencies (f₀) of 4 and 6 GHz. The designed microstrip quarter wave coupled bandpass filters reject the second and third harmonics at the higher frequencies and having the improved insertion loss of < 1 dB and return losses of 36 and 38 dB, respectively. For the proposed optimized bandpass filters implementation Rogers substrate material with the relative dielectric constant of 3.55, a standard thickness of 0.020 is used and the simulation performed on high frequency simulation software. The proposed filters are fabricated and tested in a vector network analyzer, and obtained test results are compared to the simulated results.