Dual-Band Antenna with OAM Mode Radiated by Ground Plane

Antennas that radiate orbital angular momentum (OAM) modes are usually large and have complex structures. In this paper, in combina-tion with characteristic mode analysis, the ground plane is used as the OAM wave radiator. To excite degenerate modes of the ground plane with phase quadrature by using a single-fed structure, two bent metal strips with grounded ends are introduced around the rectangu-lar ground plane, and a corner of one of the bent strips is set as the feeding point. For ground radiators, a first-order OAM mode is gener-ated at the high-frequency end by synthesizing the degenerate modes. In case of the bent side strip, an inverted-F antenna that operates in the low-frequency mode is formed. This compact antenna has dual-band characteristics and facilitates simple feeding, which makes it suitable for mobile terminal applications.