In this letter, a compact tri‐notched wideband bandpass filter based on stub‐loaded ring resonator (SLRR) and shorted stub‐loaded stepped impedance resonators (SSLSIR) with wide upper stopband is presented. The wideband characteristic is excited by coupling SLRR and SSLSIR with the arrangement of defected ground structures on the back of the substrate. By placing two sets of SSLSIRs inside and outside of the SLRR, three reflection poles can be formed in passband to introduce three notch bands with adjustable center frequencies. The quarter‐wavelength inter digital coupled lines are used to generate multiple transmission zeros to suppress high‐order harmonics to achieve a wide upper stopband characteristic. For validation, a wideband bandpass filter with a passband from 2.2 to 7.5 GHz and notch bands at 2.87, 5.69, and 6.5 GHz is fabricated. Measured results show that the 20 dB attenuation upper stopband can extend to 29 GHz.

中文翻译：

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紧凑的三切口宽带带通滤波器，基于多个谐振，具有较高的上阻带

在这封信中，提出了一种基于短负载环形谐振器（SLRR）和具有较宽的上阻带的短的短负载步进阻抗谐振器（SSLSIR）的紧凑型三缺口宽带带通滤波器。通过将SLRR和SSLSIR与有缺陷的接地结构在基板背面的排列耦合，可以激发宽带特性。通过在SLRR的内部和外部放置两组SSLSIR，可以在通带中形成三个反射极，以引入三个具有可调中心频率的陷波带。四分之一波长的数字间耦合线用于生成多个传输零点，以抑制高次谐波，以实现较宽的上阻带特性。为了进行验证，制造了一个宽带带通滤波器，其通带范围为2.2至7.5 GHz，陷波频段为2.87、5.69和6.5 GHz。