In this paper, we have introduced a compact eight-element antenna array for triple-band MIMO (multi-input multi-output) operation in 5G (fifth generation) mobile terminals, which consists of two symmetric four-element sub-arrays disposed, respectively, along two long side-edges of the system ground plane of the mobile terminal. This antenna element can operate at two dual-wideband of 3250-3820 MHz and 4790-6200 MHz with three resonance frequencies which can fully cover 5G NR (New Radio) Band-N78 (3300-3800 MHz), China 5G-Band of 4800-5000 MHz and LTE Band-46 (5150-5925 MHz). The main parameters that characterize the performance of the proposed MIMO antenna system, such as bandwidth, reflection coefficient, isolation (more than 10.5 dB), total radiation efficiency (more than 43%), ECC (envelope correlation coefficient, less than 0.12) and CC (channel capacity, 34.9-37.6 bps/Hz), are analyzed and presented in this paper. Besides, the effects of single-hand and dual-hand on performance of the MIMO antenna system are also discussed. The structure of antenna element is only 15 mm×3 mm (0.175 λ0 × 0.035 λ0，λ0 is the free-space wavelength at the frequency of 3.5 GHz) with a very small ground clearance of 13 mm×2 mm on the main board of the proposed mobile terminal. The antenna system has the possibility to be used in 5G mobile terminals with triple-band operation, narrow frame and large display. The corresponding antennas prototype is fabricated and measured; and a quite good agreement between simulation and measurement is obtained.

A novel fan-out wafer-level packaging (FOWLP) technology with double-sided redistribution layers (RDLs) and tall copper vertical interconnects is described. The design of a dual-polarized magnetoelectric (ME) dipole antenna based on this new packaging technology is presented. It is shown that the antenna with a size of $10\times10$ mm ² achieves good impedance matching and a stable radiation pattern over a wide bandwidth from 25 to 43 GHz, which can cover most of the millimeter-wave (mmWave) bands of the fifth-generation (5G) mobile networks in different countries. The measurement results demonstrate that the antenna is well suited for FOWLP technology and can be used for phased-array modules in 5G wireless communication systems.

In this paper, a K-band antenna with ±60° beam scanning is proposed for a mmWave (millimeter-Wave) radar sensor. Especially, we take advantages of the magnetic dipole principle, and design the antenna by employing via holes in three sides, so as to form a cavity which can be equivalently considered as magnetic dipole, resulting in the 3 dB beam width as wide as 140° in E-plane. We cascade the mmWave antenna to 4×1 and 4×4 arrays for radar transmitting and receiving, respectively. The antenna array is fabricated and implemented to a K-band radar and its wide-angle beam scanning performance is evaluated by the radar’s distance and angular detections.

Millimeter-Wave (mmWave) antennas for 5G mobile terminals require a wide bandwidth, large-angle beam scanning, low-profile design, and multi-substrate compatibility for module-level integration. In this paper, we propose one candidate design employing a patch structure with the shorting pin to particularly generate extra zero modes. By taking advantages of the 2 ^nd zero-mode with the TM ₀₁ mode, we can obtain a wide bandwidth covering 23.5~28 GHz, a large-angle beam scanning with ±60°, as well as keep the substrate as low profile as 0.508 mm. Thanks to the zero-mode induced patch-type design, it is compatible to multi-layer configuration possessing the extensibility and flexibility for further module design. We experimentally valid the design of a $4\times2$ array with multi-layer configuration in a cell phone environment. Good RF performances with ±60° scanning in the wide bandwidth indicate this proposed design can be an appropriate candidate for 5G mobile terminals.

A dual-functional antenna array operating in the long term evolution (LTE) band 42 (3.4–3.6 GHz) and 5.8-GHz wireless wide area network (WLAN) band (5.725–5.875 GHz) for multiple-input multiple-output (MIMO) applications in 5G smartphones is proposed. The proposed 8-antenna array is composed of two different antenna elements, namely, the folded L-shaped antenna and couple-fed Ushaped antenna. It can be applied in the 8 × 8 (by using 8 antenna elements) and 4 × 4 (by using 4 antenna elements) MIMO system across the LTE band 42 and 5.8-GHz WLAN band, respectively. The quasiorthogonal polarization, balanced mode excitation and pattern diversity are properly used to achieve high isolation within the operation bands. A prototype of the proposed antenna array was fabricated and measured. The measured isolations in the LTE band 42 (6-dB impedance matching) and 5.8-GHz WLAN band (10-dB impedance matching) are better than 17.1 dB and 34.6 dB, respectively. The total efficiencies are 45%–62% and 52%–59% in the two operation bands, respectively. Besides, the measured envelope correlation coefficients (ECCs) are less than 0.045 and 0.0001, the calculated peak ergodic channel capacities are 37.9 bps/Hz and 19.3 bps/Hz in the 8 × 8 or 4 × 4 MIMO system across the operation bands. Furthermore, user’s hand and head effects are investigated and desirable results are obtained. The above results show that this proposed antenna array is a good candidate for MIMO applications in smartphones.

In this letter, for the first time, we report a microelectromechanical system (MEMS)-modulated scanning beam metamaterial antenna based on surface micromachining process. The antenna is implemented by cascading periodical metamaterial modules with a unit length of less than λ _g /5 to make an electromagnetically homogeneous waveguide, of which the MEMS cantilevers are monolithically integrated in each unit as a radio frequency (RF) switch to modulate the phase constant β, and thereby to realize the scanning beams in the fixed frequency around 8 GHz. Experiments that verified the MEMS-modulated scanning radiation beams are tuned from the backward (around -15°) to the broadside (around 0°) and to the forward (around +15°) directions as the RF-MEMS switches are, respectively, actuated from the states of 0000-0000 (switches in all of the eight units are OFF) to 1010-1010 (switches in the unit of numbers 1, 3, 5, and 7 are ON) and to 1111-1111 (all switches are ON).