Frequency-Scanning Planar Antenna Based on Spoof Surface Plasmon Polariton

In this letter, a frequency-scanning planar antenna composed of a phase gradient metasurface and feed structure is proposed. The phase gradient metasurface can couple the wave from the feed into a spatial radiated wave whose propagation direction is manipulated by frequency as long as the feed provides a similar electromagnetic field to that of spoof surface plasmon polariton rather than exciting the spoof surface plasmon polariton. Both the simulation and measured results demonstrate the antenna works well in the frequency range from 8.9 to 9.5 GHz, that the magnitude of reflection coefficient maintains lower than -10 dB with minimum value of -20 dB, and the gain maintains at about 10 dB. The max gain direction of the antenna changes with frequency that the beam pointing angles at 8.9, 9.1, 9.3, and 9.5 GHz are -12°, -8°, -4°,and 0°, respectively.