This paper presents the design of $8 \times 8$ multiple-input multiple-output (MIMO) antennas for future 5G devices, such as smart watches and dongles. Each antenna of the MIMO configuration occupies $3 \times 4$ mm ² and is printed on the top layer of the substrate in the form of a rotated H-shaped patch. The substrate used for the design is a $31.2 \times 31.2 \times 1.57$ mm ³ , Rogers RT-5880 board, with a dielectric constant of 2.2. The top layer of the substrate has eight MIMO antennas, whereas the bottom layer is composed of ground plane. The ground plane is an electromagnetic bandgap-based structure designed for the enhancement of gain and efficiency. Each antenna is fed from the bottom layer of the substrate through vias to avoid any spurious radiation. The MIMO antennas resonate at 25.2 GHz with a 6-dB percentage bandwidth of 15.6%. The gain attained by the antennas in the entire bandwidth is above 7.2 dB with a maximum value of 8.732 dB at the resonant frequency. Likewise, the value of efficiency attained by the antennas in the entire bandwidth is above 65% with a maximum value of 92.7% at the resonant frequency. The simulation and measurement results have substantiated a good performance of the MIMO antennas, thus making them suitable for compact 5G devices.

This paper presents compact pattern reconfigurable antennas for mobile handsets in MIMO configuration. Each antenna of the MIMO configuration being coupled fed monopole in meandered form is capable of covering several cellular frequency bands in the range of 1.75–2.67 GHz including 4G‐LTE, 2G‐GSM, 3G‐UMTS, and WLAN. The MIMO antennas are printed diagonally at the left and right no‐ground portions on the top layer of the substrate to enhance the isolation performance. The substrate used is FR‐4 with relative permittivity of 4.35 and loss tangent of 0.02. The volume of the substrate is 120 × 65 × 1.6 mm³ with each antenna occupying an area of 26.5 × 14.5 mm². The pattern reconfigurability is achieved by connecting and disconnecting a 4.5 × 2 mm² metallic strip using the p‐i‐n diode switch. The antennas are pattern reconfigurable in the frequency range of 1.9–2.1 GHz. The isolation achieved is better than 16 dB over all the frequency bands covered by each antenna. A prototype has been fabricated and tested. The simulated and measured results show a good performance of the MIMO antennas. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:148–156, 2017

Real-time tracking, together with monitoring and data collection of human body signals, happens through RFID technology amalgamated with wearable electronics called wearable RFID sensors. Modern sensors find placement in clothing items as well as accessories, and they also operate beneath the skin. The sensors serve several applications across healthcare monitoring, together with asset tracking and security system functions. This article delivers an extensive examination of body-area RFID antenna design issues regarding operating frequencies with biological tissue effects and antenna performance, together with safety compliance aspects. A multicomponent antenna system works as an RFID shield and functions for Bluetooth along with Wi-Fi (2.4 GHz), and includes temperature and sweat sensors for healthcare distance monitoring. The designed antenna spans 600 MHz (2.2–2.8 GHz) within its 25 × 40 × 1.5 mm³ dimensions. This antenna finds optimal application in wearable systems because it utilizes semi-flexible Rogers RT5880 substrate material. The system obtains miniaturized dimensions through the implementation of two E-shaped slots, which allow the device to operate in the desired frequency range. Stability characteristics allow the antenna to operate properly near human bodies and meet the SAR safety requirements of 1.6 W/kg at its operating frequency. Realistic performance tests produced efficient results close agreement between simulated and measured data, thus validating the design potential as a remote healthcare monitoring solution.

The optimal design of Multiple-Input Multiple-Output (MIMO) antennas is significant for next-generation smartphone solutions with the appearance of further communication. This paper describes the design, simulation, and measurements of a ten-element MIMO antenna for n79 at 4.4–5.0 GHz, n102 at 5.925–6.425 GHz, and n104 at 6.425–7.125 GHz ranges that will be implemented in today’s smartphones. The proposed antenna system has a maximum dimension of 158 mm × 60 mm and will use the low-cost FR-4 as the dielectric material. The design procedure is carried out with a lot of care to ensure that it does not compromise the spatial characteristics and at the same time minimizes the mutual coupling between the nearby antenna dimensions. High isolation and low ECC values are simulated using capturing techniques on the antenna geometry and its element position for proper MIMO performance improvement. The constructed antenna system portrays good performances in the intended bands as evidenced by the reflection coefficient values, radiation patterns, and individual gains. The performance of the above proposed ten-element MIMO antenna system in terms of bandwidth efficiency, diversity gain, and channel capacity loss is discussed. It also satisfies the demands of current standards of wireless communications and provides future possibilities for higher data transmission rates and message reliability in next-generation smartphone applications. Here, the application of the FR-4 substrate is remarkable as it provides comparatively better performance with significantly easier manufacturing and less cost, and thus, the design has good possibilities to be commercially viable. This work can be understood to form part of ongoing research in enhancing the advancement of the smartphone’s antenna technology, which offers a scalable approach to the prospective spectrum altitude and the emergent surge in the data rates of mobile communication.

This article presents a design for high-gain MIMO antennas with compact geometry. The proposed design is composed of four antennas in MIMO configuration, wherein, each antenna is made up of small units of microstrip patches. The overall geometry is printed on the top layer of the substrate, i.e., Rogers RT-5880 with permittivity of 2.2, permeability of 1.0, dielectric loss of 0.0009, and depth of 0.508 mm. The proposed design covers an area of 29.5 × 61.4 mm², wherein each antenna covers an area of 11.82 × 25.28 mm². The dimensions of the microstrip lines in each MIMO element were optimized to achieve a good impedance matching. The design is resonating at 61 GHz, with a wide practical bandwidth of more than 7 GHz, thereby covering IEEE 802.11ad WiGig (58–65 GHz). The average value of gain ranges from 9.45 to 13.6 dBi over the entire frequency bandwidth whereas, the average value of efficiency ranges from 55.5% to 84.3%. The proposed design attains a compact volume, wide bandwidth, and good gain and efficiency performances, which makes it suitable for WiGig terminals.