Design of Dual Ultra-Wideband Band-Pass Filter Using Stepped Impedance Resonator λg/4 Short Stubs and T-Shaped Band-Stop Filter

Portable wireless communication systems are increasingly in demand in small sizes for human convenience. In wireless communication systems, the performance, size, and unit cost are very important. A band-pass filter is important to sharp cut-off frequency characteristics, size, and frequency selectivity in wireless communication systems. The band-pass filter has three types of techniques in the transmission-zero method, stub-loaded resonator, and stepped impedance resonator for the sharp cut-off frequency characteristic, adjustable bandwidth, and excellent frequency response characteristics. To obtain these characteristics, the impedance ratio and length of a stub are mainly adjusted. It also utilizes a multi-mode technique to increase bandwidth. However, it is analyzed that the problem of reducing the size of the device still remains. To solve these problems, the paper is applied to a stub-loaded resonator and a stepped impedance resonator to control the impedance ratio and the length of the stub to obtain the results of the transmission-zero method, bandwidth control, and size reduction through the folded structure. Dual-band bandwidth was secured by integrating a T-shaped band-stop filter. The designed band-pass filter has center frequencies of 243 GHz and 7.49 GHz, and the insertion loss of a proposed band-pass filter is 0.102 dB and 0.103 dB. Additionally, the return loss of a proposed band-pass filter is 19.13 dB and 19.96 dB, respectively. The bandwidth of a filter is 120% and 105%, respectively. The size of the filter is 0.0708 lambda g x 0.0533 lambda g. The designed filter has a good skirt phenomenon, small size, low insertion loss, and dual-band characteristics.

Automated summary

With the increasing demand for portable wireless communication systems in small sizes, the performance, size, and unit cost are crucial factors to consider. Band-pass filters play an important role in achieving sharp cut-off frequency characteristics, size reduction, and frequency selectivity in wireless communication systems. Different techniques such as the transmission-zero method, stub-loaded resonator, and stepped impedance resonator are utilized to achieve specific characteristics in band-pass filters.