Broadband Planar Filtering Antenna With High Out-of-Band Suppression Based on Spoof Surface Plasmon Polariton

This letter proposed a broadband, low-profile, and planar filtering antenna based on spoof surface plasmon polariton (SSPP). Periodic gaps are loaded between symmetric SSPP units to serve as a radiator element of the antenna. The antenna benefits from the dispersion characteristics of the SSPP radiator element, so efficient radiation over broadband has been achieved. The high-frequency cut-off characteristics of SSPP are also employed to obtain filtering performance. To verify the method, a prototype with a low profile of only 0.012<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">λ</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> is designed and fabricated. The simulated and measured results agree well with each other, demonstrating good performances with large impedance bandwidth of 50.6% [(5.16 to 8.32) GHz], high peak gain of 7.45 dBi, together with high out-of-band suppression levels of about 18 dB in the lower stopband and 6.3 dB in the upper stopband.