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

<div>The voltage probe-based center coupling between the microstrip line and SIW resonator: (a) design and (b) band-stop filter response (<span class="nowrap"><svg height="8.55521pt" id="M12" style="vertical-align:-0.2063904pt" version="1.1" viewbox="-0.0498162 -8.34882 43.3909 8.55521" width="43.3909pt" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><g transform="matrix(.013,0,0,-0.013,0,0)"><path d="M483 97L471 123C436 91 401 65 392 65C388 65 384 74 390 106C414 239 444 378 457 429L455 433C444 433 429 436 416 439C392 444 368 448 344 448C281 448 204 415 152 376C71 315 23 205 23 103C23 21 57 -12 85 -12C114 -12 149 6 185 34C231 70 285 119 329 183H331L309 81C292 0 308 -12 326 -12C350 -12 421 24 483 97ZM374 387C370 363 356 291 345 261C315 193 181 50 139 50C124 50 110 71 110 118C110 224 153 331 218 379C238 394 271 402 301 402C329 402 359 394 374 387Z"></path></g><g transform="matrix(.013,0,0,-0.013,10.212,0)"><path d="M535 323V373H52V323H535ZM535 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International Journal of RF and Microwave Computer-Aided Engineering

fig2

Figure 2

Figure 2: Frequency-Tunable SIW Band-Reject Filter with Increased Fundamental Mode Bandwidth for Spectrum Underlay Cognitive Radio 