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A multimode antenna for sub‐6 GHz applications in metal‐rimmed mobile terminals is presented. The proposed antenna is composed of a multibranch driven strip, a parasitic grounded strip, and an integrated metal rim that is connected to the ground through two shorting stubs. The proposed antenna occupies a 5‐mm clearance area, featuring simple design without lumped components. The working principle of the antenna is analyzed in detail in terms of its multiple resonant modes and current distributions. The resultant |S11| ≤ −6 dB impedance bandwidth of the antenna covers the LTE 700/2300/2500, UMTS, GSM 850/900, DCS, PCS, and recently proposed n77 to n79 5G NR frequency bands. The prototype of the antenna is fabricated and the design is well validated by experimental results. [ABSTRACT FROM AUTHOR]

A high gain antenna system based on a phase gradient metasurface (PGM) with a four-split ring (FSR) structure is proposed in this letter, which combines the radiation functionalities of transmission-mode, bidirectional-mode, and reflection-mode. The Vivaldi antenna, as a feed source, is placed at the focal point of the metasurface (MS). Then the quasi-spherical wave launched by the feed source undergoes abnormal refraction and reflection when passing through PGM, which proves that the PGM proposed can control the wavefront by altering the frequencies so that the proposed antenna can achieve multimode radiation. In contrast with traditional unidirectional antenna, the proposed antenna has beam converge characteristic in transmission direction at 15.7 GHz with a peak gain of 20.4 dBi, bidirectional radiation at 16.5 GHz, and reflection direction at 17.1 GHz with a peak gain of 16.5 dBi. The results of the simulation and experiment are in good consistency. The proposed PGM has potential applications in designing high-performance multifunctional antennas in communication systems. [ABSTRACT FROM AUTHOR]

A compact antipodal Vivaldi antenna (AVA) with metamaterial half-lens (MHL) for beam control is proposed. The proposed AVA has three different beam forms in the operating frequency band, including end beam from 3 GHz to 9 GHz, beam splitting at 12.2 GHz, and beam deflection at 13 GHz. Furthermore, it can perform beam scanning by adjusting operating frequency from 12.7 GHz to 13.5 GHz. The simulation indicates that the proposed AVA has a −10 dB impedance bandwidth of 143.6% (2.3–14.0 GHz) and a −3 dB gain bandwidth of 100% (4.5–13.5 GHz), which is consistent with the experimental results. Besides, the gain of the proposed AVA has an improvement of about 2 dB in the working band. As a new method to control the beam, the loading of MHL realizes the design of a small size and multi-function antenna, which can be widely used in wireless communication systems. [ABSTRACT FROM AUTHOR]