Frequency-Tunable SIW Band-Reject Filter with Increased Fundamental Mode Bandwidth for Spectrum Underlay Cognitive Radio

Table 1

Comparison of a proposed filter with the state-of-the-art.

	Details	Number of diodes	Tuning range
[7]	Dual-band-stop filter with one tunable stopband	2	3.5-4.1 GHz (15%)
[8]	Frequency and bandwidth tunable band-stop filter	2	2.8-3.4 GHz (19.3%)
[9]	-band tunable band-stop filter	2	10.02-10.34 GHz (3.1%)
[10]	Half-mode band-stop filter	1	2-2.5 GHz (22.2%)
[11]	Coaxial band-stop filter	2	0.77-1.25 GHz (47%)
[12]	Octave tunable combline band-stop filter	12	0.56-1.18 GHz (71%)
This work	Band-stop filter with high fundamental mode bandwidth	1	2.9-4.4 GHz (41%)