Novel Low-Pass Filter Structures Using Spur-Lines to Generate Additional Attenuation Poles

We propose two novel low-pass filter (LPF) structures that have generated additional attenuation poles from applying spur-lines to typical open-stub LPFs. The first structure has the added serial lines, and second parallel open stub. From characteristic analyses of filters with proposed design, it was confirmed length spur-line an important variable for controlling stopband bandwidth depth. types LPFs were fabricated then validated by agreement between theoretical measured results. results, bandwidths serial- parallel-configuration improved approximately 4.7 times 1.4 defined reference level, respectively, compared LPF.