A 60GHz ultra wideband rectangular ring bandpass filter with second harmonic suppressed

This paper designs an Ultra Wideband bandpass filter using high frequency printed circuit broad (HFPCB). The filter is composed of two cascaded ring resonators with tuning stubs, perturbation stubs and equivalent T-shaped lines. The perturbation stub can excite a dual mode to improve stopband rejection. The T shaped line can create a transmission zero at the second harmonic and improve upper stopband rejection. The simulated center frequency of Alter is 60GHz with the minimum insertion loss as 0.85dB and the relative 3dB bandwidth is 47.4%. the main size of the filter is 3.1×5.4 mm².