Design of a bandpass filter with wide passband and wide rejection bandwidth

A bandpass filter with wide passband and wide rejection bandwidth is presented. The filter is composed of bandpass filters (BPF), together with a lowpass filter (LPF). With the simple structure, a good performance is proposed and implements simultaneously. The fractional bandwidth of the BPF is 55% (1.45-2.55 GHz), and with rejection level of 20 dB up to more than ten times of the passband frequency. The 50 ¿ I/O ports can be directly connected to the filter without any adjustment, which is massively reducing the fabrication and analysis difficulties.