This technology is an ultra-wideband channel bandpass filter that forms a multi-ring structure by connecting input and output coupled lines, which are placed in parallel, to both a main resonant transmission line and a separate bypass line. It creates transmission zeros above and below the passband using the phase difference of signals passing through the two paths.
Parallel-coupled microstrip bandpass filters are based on half-wavelength resonators, which have the disadvantage of increasing in length as the order increases. Furthermore, they generate unwanted harmonics that negatively affect adjacent channels, and because it is difficult to find parameter combinations that precisely meet specifications, they have historically relied on orthogonal polynomial approximation tables.
This technology creates transmission zeros in the stopband higher than the passband using the bypass line, and in the lower stopband using the input and interdigital coupled lines, resulting in steeper slopes on both sides of the passband. By dividing the main transmission line and the bypass line into stepped sections with varying widths and lengths, the size is reduced while design flexibility is increased. It can be applied to the channel selection stage of multi-channel ultra-wideband wireless receivers, improving isolation between adjacent channels while reducing module footprint.
This invention was developed with support from the Ministry of Science, ICT and Future Planning for research on satellite filter design based on coupling matrix optimization.
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