Five-notch ultra-wideband filter with miniaturization characteristics

To effectively suppress the interference of narrowband signals to the ultra-wideband system, a five- notch ultra-wideband bandpass filter with miniaturization characteristics is proposed. The filter proposes a multiple-mode resonator (MMR) structure based on a uniform impedance resonator and loaded with three open-circuit stubs. At the same time, a new type of approximate "王" shape resonator is used on the multiple-mode resonator to achieve triple notched bands and uses the L-shaped resonator and Hilbert fractal curve slit to create single notched band, respectively. After HFSS simulation and optimization, the passband range is 3.0-11.2GHz, the stopband attenuation is 55dB at 2.68 GHz, and the in-band flatness is good. Among them, the five-notch filter notch frequency occurs at 4.44GHz, 6.56GHz, 7.3GHz, 8.22GHz, 9.66GHz, which can effectively suppress the radio altimeter ITU band, the Indian national satellite communication C band, the X satellite band, Interference in the International Telecommunication Union, and radio navigation bands, suitable for various ultrawideband systems.