Design of a new wide-stopband absorptive band-stop filter

The signal in the stopband of traditional band-stop filter is almost completely reflected back to the source, which will cause interference to the communication signal and easily cause equipment damage. In order to solve this problem, based on the low-pass prototype of Butterworth filter, a new fourth-order Butterworth absorptive band-stop filter is proposed by using the design method of open-circuit stubs. The center frequency of this filter is 2.4GHz. A wave absorbing resistor is cleverly introduced at the position of the first open-circuit stub, which can well absorb the stopband signal and reduce the electromagnetic wave energy reflected back to the source. Through HFSS simulation, we can clearly see its good performance in stopband, which has practical application value.