Multiwideband Bandpass Filter Based on Folded Quad Cross-Stub Stepped Impedance Resonator

Table 1

Summary of the proposed multiwideband BPF comparison.

Ref	Year	Method	Center frequency (GHz)	Transmission coefficients (dB)	−3 dB FBW (%)	Size (λg)
[8]	2006	Quarter-wavelength SIRs	1.57/2.45/5.25	−1.50/−1.34/−0.90	8.2/7.3/9.9	0.06 × 0.09
[10]	2007	Trisection SIRs	1.57/2.45/3.50	−1.95/−2.42/−2.00	7.0/4.2/9.0	0.12 × 0.09
[13]	2006	Cascaded multiband resonators	2.30/3.70/5.30	−2.50/−1.90/−2.90	3.8/6.8/5.0	0.28 × 0.68
[14]	2009	Loaded crossed resonator	2.40/3.50/5.20	−1.40/−1.50/−1.80	3.0/3.0/3.0	0.18 × 0.20
[16]	2010	Trimode stub-loaded resonators (SLRs)	2.45/3.56/5.90	−0.80/−1.60/−1.80	7.59/5.86/3.71	0.16 × 0.20
[17]	2011	Stub-loaded quarter-wavelength resonator	1.80/2.40/3.00	−0.30/−0.30/−0.20	9.4/12.5/6.4	0.23 × 0.30
[19]	2010	Stub-loaded and DGS resonator	2.45/3.50/5.25	–0.90/−1.70/−2.10	12.3/6.2/3.3	0.26 × 0.32
[22]	2010	Crossed open stubs	2.45/3.50/5.22	−0.80/−0.80/−0.80	15.1/13.4/7.6	0.20 × 0.30
[27]	2018	Two stub-loaded dual-mode resonators	1.57/2.40/3.45	−0.70/−1.14/−0.3	28.6/9.75/5.21	0.44 × 0.56
[28]	2020	Folded open-loop stepped impedance resonators	2.17/3.51/4.86	−0.46/−0.49/−1.30	12.4/11.4/13.3	0.22 × 0.22
[32]	2019	Common resonator feeding	3.0/6.0/9.0	−3.06/−2.71/−3.16	3.06/2.71/3.16	0.15 × 0.12
[33]	2019	Asymmetric shunted-line stepped impedance resonator	1.57/2.40/3.50	−0.10/−0.09/−0.11	5.2/4.25/2.7	0.076 × 0.26
[34]	2020	Multicoupled line stub-SIR	1.75/2.55/3.55	−0.55/−1.37/−1.37	21.2/4.7/8.4	0.32 × 0.12
This work	Figure 12(a)	Quad cross-stub stepped impedance resonator (QC-SSIR)	0.81/1.71/2.58	−0.60/−1.49/−1.93	49.3/18.7/13.9	0.27 × 0.66
	Figure 12(b)	Folded quad cross-stub stepped impedance resonator (FQC-SSIR)	0.82/1.80/2.62	−0.57/−1.21/−1.76	49.6/17.7/12.5	0.27 × 0.35

λ_g is the guided wavelength on the substrate at the center frequency of the first passband.