A miniaturized asymmetrical bandpass filter using the inductive load and the coupled lines

This work presents the compact bandpass filter using asymmetrical couplers, coupled lines and inductive load. In the design, it is shown that the length of the two asymmetrical couplers are shorter when the inductive load is introduced, causing the significant reduction in the total filter size approximately 50% while the filter performance still maintains. Then, the coupled lines are employed. As a result, the filter gives not only the good return loss but also the excellent sharp-edge band rejection. In the experiment, the filter gives the fractional bandwidth of about 31.47 percent with the return loss of 15dB. Additionally, the filter performance in simulation and the experiment are welled agreed.