Compact K-band bandpass filter on high-k LiNbO3 substrate

A novel miniaturized microstrip-line filter with a pair of meandering resonators on lithium niobate LiNbO3 substrate with a high dielectric constant is proposed. A stepped-impedance structure is integrated into this new filter simultaneously to reduce dimensions and suppress the spurious responses. A substrate with a high dielectric constant is also effective in reducing the filter size because it has a high coupling efficiency. The cross-coupling effect can be achieved in this designed filter. A copper (Cu) interconnection was also used in this investigation to improve further the quality factor and the insertion loss of this filter. The filter has two transmission zeros one on each side of the passband. The experimental results in the K-band verify the design.