A dual-polarized hybrid eight-antenna array operating in the 2.6-GHz band (2550–2650 MHz) for 5G communication multi-input multi-output (MIMO) operation in the smartphone is presented. The proposed hybrid antenna array elements are symmetrically placed along the long edges of the smartphone, and they are composed of two different four-antenna array types (C-shaped coupled-fed and L-shaped monopole slot) that exhibit orthogonal polarization. Therefore, coupling between the two antenna array types can be reduced, and the MIMO system performances are enhanced. A prototype of the proposed eight-antenna array is manufactured and measured. A good impedance matching (10 dB return loss or better), desirable cross-polarization discrimination (better than 15 dB), and an acceptable isolation (better than 12.5 dB) are obtained. Envelope correlation coefficient and channel capacity are also calculated to evaluate the MIMO performances of the proposed antenna array.

Eight-Port Orthogonally Dual-Polarized Antenna Array for 5G Smartphone Applications

A novel spade-shaped ultrawideband (UWB) printed planar monopole antenna with triple band-notched characteristics is proposed. By employing a hook-shaped defected ground structure (DGS) in each side of the ground plane, embedding an Omega-shaped slot on the radiating patch as well as adding a semi-octagon-shaped resonant ring on the back side of the antenna, triple notched frequency bands are achieved. The proposed antenna has been successfully simulated, fabricated, and measured. Effects of the key parameters on the frequency ranges of the notched bands are also investigated. The measured impedance bandwidth defined by VS WR < 2 of 10.1 GHz (2.9-13 GHz), with the triple notched bands of 3.3-3.9, 5.2-5.35, and 5.8-6.0 GHz, is obtained. Measured group delay and transmission characteristics indicate that the antenna has good transient response. Furthermore, the proposed antenna shows the merit of insensitivity to both finite ground size and fabrication tolerances.

Novel Planar UWB Monopole Antenna With Triple Band-Notched Characteristics

In this letter, a compact self-decoupled antenna structure is proposed for the fifth-generation multiple-input--multiple-output (MIMO) operation in mobile terminals. The antenna structure consists of two adjacent antenna elements, which are placed very close (1.2 mm or 0.014λ) to each other and located on the same side of the system ground plane. By sharing one common grounding branch for the two adjacent antenna elements, a compact self-decoupled antenna pair can be obtained. The MIMO antenna system is optimized to operate in the 3.5 GHz (3.4–3.6 GHz) band with isolation better than –17 dB. An antenna prototype is fabricated, and good agreement between simulation and measurement is obtained.

MIMO Antenna With Compact Decoupled Antenna Pairs for 5G Mobile Terminals

A novel integrated antenna solution for wireless handheld devices is proposed for the existing 4G standards and upcoming 5G systems for broadband, high data rate communications. The complete antenna system is a unique combination of a multiple-input-multiple-output (MIMO) antenna system at microwave frequencies and a millimetre (mm)-wave antenna array. The MIMO antenna system consists of two reactive loaded monopoles while the mm-wave array consists of a planar 2 by four slot antennas. The integrated antenna system covers the frequency bands from 1870 to 2530 MHz for 4G standards along with the upcoming 5G mm-wave band at 28 GHz. In addition, the integrated antenna system is planar and is designed for typical smart phone devices with a standard 60 mm by 100 mm by 0.965 mm back plane. Excellent field correlation values were obtained across the 4G band while realised peak gain values of 4 and 8 dBi were, respectively, measured for the MIMO and mm-wave antenna arrays. The proposed antenna design may also be useful for other compact implementations that support 4G and 5G communications.

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Compact 4G MIMO antenna integrated with a 5G array for current and future mobile handsets

This article presents a wideband orthogonal-mode dual-antenna pair with a shared radiator for fifth-generation (5G) multiple-input multiple-output (MIMO) metal-rimmed smartphones. The wideband decoupling property of the dual-antenna pair is realized by the combination of the orthogonal monopole/dipole modes in the lower band and the orthogonal slot/open-slot modes in the higher band. With the orthogonal-mode design scheme, the dual-antenna pair shows a wide impedance bandwidth of 3.3–5.0 GHz and a high isolation of more than 21.0 dB across the entire band without using any external decoupling structures. By arranging four such dual-antenna pairs at two side edges of the smartphone, an $8 \times 8$ MIMO system is fulfilled. Both the simulation and measurement results show that the proposed $8 \times 8$ MIMO system could offer an isolation of better than 12.0 dB and an envelope correlation coefficient of lower than 0.11 between all ports. The measured average antenna efficiencies are 74.7% and 57.8% for the two antenna elements of the dual-antenna pair. We portend that the proposed design scheme, with merits of shared radiator, wide bandwidth, and metal rim compatibility, has the potential for the application of future 5G smartphones.

Wideband 5G MIMO Antenna With Integrated Orthogonal-Mode Dual-Antenna Pairs for Metal-Rimmed Smartphones

An eight-port antenna array operating in 3.5 GHz band (3400–3600 MHz) and 5 GHz band (4800–5100 MHz) for fifth-generation multiple-input multiple-output (MIMO) in mobile handsets is presented. To reserve space for 2G/3G/4G antenna configuration, the eight-antenna array formed by two quad-antenna arrays is printed along the two long frames of the smartphone. Each antenna array unit is formed by a folded monopole and a gap-coupled loop branch, and they are disposed on the upper and bottom sides of the system circuit board, respectively. As the gap between each array unit is only 10 mm, a neutralized line is introduced between the two middle antenna units for reducing the mutual coupling. The measured results have exhibited good impedance matching and isolation. To evaluate the MIMO performance, the envelope correlation coefficient, mean effective gain, and ergodic channel capacity are investigated. Furthermore, the hand phantom effects and display panel effects are also given.

Side-Edge Frame Printed Eight-Port Dual-Band Antenna Array for 5G Smartphone Applications

The design and analysis of an ultra-wideband (UWB) aperture antenna with dual band-notched characteristics are presented. The antenna consists of a circular exciting stub on the front side and a U-shaped aperture on the back ground plane. By inserting a slot and a parasitic strip to the antenna, dual notched frequency bands are achieved. A conceptual circuit model, which is based on the measured impedance of the proposed antenna, is also shown to investigate the dual band-notched characteristics. The measured impedance bandwidth defined by VSWR<2 of 9.0 GHz (2.2-11.2 GHz), with the dual bands of 3.25-4.25 and 5.0-6.05 GHz notched, is obtained.

Implementation and investigation of U-shaped aperture UWB antenna with dual band-notched characteristics

This letter presents a low-cost, single-layer, dual circularly polarized (CP) series-fed antenna based on the sequential rotation technique for millimeter-wave (MM-wave) applications. The series-fed working form endows the proposed antenna with more compact structure and lower ohmic, dielectric losses caused by the feeding network compared with parallel-fed antennas. The curved microstrip transmission lines are adopted as radiation elements; therefore, the whole antenna can be etched on a single-layer laminate using standard printed circuit board technology. These characteristics make the antenna a competitive candidate for MM-wave applications. To validate the proposed design, a dual-CP antenna operating at 30 GHz is fabricated. Based on the measurement, the proposed antenna has a 3 dB gain bandwidth of 1.97 GHz, the measured $| {{S_{21}}} |$ is lower than −20 dB, and the axial ratios are lower than 3 dB in the aforementioned frequencies.

A Low-Cost, Single-Layer, Dual Circularly Polarized Antenna for Millimeter-Wave Applications

A single square patch antenna for pattern diversity is investigated. The proposed antenna consists of a double-feed square patch antenna with a rat-race network. By switching the feeding ports, the different radiation patterns for two modes ( TM10 mode and the capacitive-loaded monopole radiating mode) operating over an overlapped frequency band from 1.88 to 2.34 GHz are achieved. TM10 mode reveals good broadside radiation patterns, and the capacitive-loaded monopole radiating mode shows conical radiation patterns. The antenna is fabricated and tested. The measured gains across the common frequency band are 8.9-9.9 and 2.8-3.8 dBi for TM10 mode and the capacitive-loaded monopole radiating mode, respectively. Moreover, the measured bandwidths of -10-dB reflection coefficient are 750 MHz (1.59-2.34 GHz, 38.2%) for TM10 mode and 880 MHz (1.88-2.76 GHz, 37.9%) for the capacitive-loaded monopole radiating mode. High isolation (<; -20 dB ) between the two feeding ports for the common impedance matching band is achieved. These results make the single dual-port patch antenna an attractive solution for 3G/4G pattern diversity applications such as in gym scenarios.

A Single Patch Antenna With Broadside and Conical Radiation Patterns for 3G/4G Pattern Diversity

A two-port pattern diversity antenna is presented. The antenna is a combination of a low-profile monocone antenna and a broadband microstrip antenna. The low-profile monocone antenna is loaded with a cup-shaped patch and shorted with four metallic wires to the ground. The broadband microstrip antenna is fed by a probe-ring-slot coupling structure. The two antennas are integrated by sharing parts of the antenna radiators, resulting in a compact structure. The difficulties of placing coaxial cables are simply solved by reusing the shorting wires. A prototype of the proposed antenna is designed, fabricated, and measured. Its overall height is 3.915 cm. The low-profile monocone antenna achieves an impedance bandwidth of 114% from 750 MHz to 2.73 GHz, covering the GSM-850/900, GSM1800/1900/UMTS, and LTE800/2300/2500 bands. The broadband microstrip antenna provides an impedance bandwidth of 44% from 1.89 to 2.9 GHz, covering UMTS/LTE2300/2500 bands. The isolation between the two antennas is greater than 15 dB in the whole bands. The low-profile monocone antenna has a monopole-type radiation pattern, and the broadband microstrip antenna has a microstrip-antenna-type radiation pattern, which indicates that the proposed antenna can provide pattern diversity characteristics. The proposed antenna is suitable for 3G and 4G indoor applications and is also compatible with 2G (GSM) applications.

Baohua Sun

Papers

Side-Edge Frame Printed Eight-Port Dual-Band Antenna Array for 5G Smartphone Applications

Implementation and investigation of U-shaped aperture UWB antenna with dual band-notched characteristics

A Low-Cost, Single-Layer, Dual Circularly Polarized Antenna for Millimeter-Wave Applications

A Single Patch Antenna With Broadside and Conical Radiation Patterns for 3G/4G Pattern Diversity

Two-Port Pattern Diversity Antenna for 3G and 4G MIMO Indoor Applications