A Scalar Impedance Surface Antenna for Generating Focusing Radial Vortex Beam

This letter presents a low-profile broadband scalar impedance surface antenna to achieve focusing radial orbital angular momentum (OAM) waves at the 17GHz. A good surface impedance of the 3x3 mm
²
square unit is obtained at the operating frequency. The antenna is designed using the holographic method with the square unit to realize a focused radial scalar vortex beam of +1 and +2 OAM mode, and the radial vortex beam is focused near z=100 mm. The whole size of the surface antenna is 117x117 mm
²
. The antenna satisfies |S11|<-10dB at 14.1-21.9 GHz. Theoretical, simulated results are presented.