Low-Profile Beamwidth Switchable Antenna Hybridizing Transmitarray and Fold Transmitarray

A low-profile antenna hybridizing transmitarray and fold transmitarray for beamwidth switching between the flat-top beam and high-gain beam is proposed in this paper. The proposed hybrid antenna is with unique advantage that it neither requires iterative process in phase compensation of flat-top beam, nor needs active devices and control structures in the array to achieve beamwidth switching. Additionally, it is low profile with height-to-diameter ratio of only 0.48. A dual-linear-polarized (dual-LP) magneto-electric (ME) dipole array is integrated as the feed. By varying the feed polarization, beamwidth switching between the flat-top beam and high-gain beam is realized. On one hand, when the feed emits y-polarized electromagnetic (EM) waves, the hybrid antenna operates as a transmitarray antenna, achieving flat-top beam radiation with a 3-dB beamwidth of 24°. On the other hand, when the feed emits x-polarized EM waves, the hybrid antenna operates as a fold transmitarray antenna, achieving high-gain beam radiation with a realized gain of 20.4 dBi. The operation band of the proposed antenna fully covers the 5th generation (5G) international mobile telecommunication (IMT) band from 24.25 to 27.5 GHz.