Integration Effects of Multiple Microstrip Patch Antennas into Small Handsets

Multiple input multiple output (MIMO) technology has been regarded as a practical approach to achieve significant increases of wireless channel capacity or reliability. Recently, the antenna's effect on MIMO system has been investigated intensively, in order to predict the true spectral efficiencies of MIMO systems in a real environment whereby realistic mobile terminals are used. Separation between multiple antenna elements is the most critical parameter affecting mutual coupling. Analytical studies have shown that for minimal or no mutual coupling, the distance between typical antenna elements needs to be at least half wavelength. However, the large separation between antenna elements is not attainable on a mobile terminal. There are a number of suggestions on how to build diversity antennas on a mobile terminal with low mutual coupling. In this context, we have developed a modified planar invert-F antenna (PIFA) and built a dual element array operating in 5.2GHz band with a separation of less than half wavelength (0.35 wavelength) and an isolation better than 28dB, as presented in our previous studies. It is noticed that mutual coupling depends on the frequency of received/transmitted signals since the distance is expressed in terms of the wavelength. Therefore, a dual-element diversity PIFA operating at the lower frequency (2.5GHz band) with an even closer separation (0.17 wavelength) has been studied in this paper.

A novel design of multiple input–multiple output (MIMO) antenna based on the log-periodic dipole array (LPDA) for the mobile handsets is presented. The antenna operates in a wide frequency range of 1.86–3.84 GHz compatible with GSM, LTE, WLAN, and WiMAX. The MIMO design consists of two symmetrical and orthogonal radiating elements and a neutralization line (NL). The radiating element comprises a LPDA having a series of printed dipoles connected together with a microstrip line. Triangular and rectangular cuts on ground plane are carried out in accordance with the LPDAs so as to increase the impedance bandwidth and isolation. The antenna elements are linked with the NL to further enhance the isolation between the radiating elements. The performance of the MIMO antenna is analyzed in terms of S-parameters, radiation pattern, gain, total efficiency, envelope correlation coefficient, mean effective gain, multiplexing efficiency; and then it is verified through the measurements. The results demonstrate that the proposed MIMO antenna has good characteristics of wideband, gain, radiation pattern, isolation, and diversity.

This paper presents the design of a compact S-shaped triple band microstrip slot antenna and its 2 × 1 Multiple Input Multiple Output (MIMO) implementation for WLAN and WiMAX applications. The designed antenna is capable of operating over the three ranges of 2.18 to 2.9 GHz, 3.04 to 3.58 GHz, and 5.16 to 5.99 GHz frequency bands. The simulated and measured results of reflection coefficient, mutual coupling, radiation pattern, envelope correlation coefficient and diversity gain of the MIMO antenna shows that it is suitable for MIMO applications.

A double-layer mushroom structure is proposed to enhance the interelement isolation of a four-element antenna system, wherein four closely positioned substrate-integrated cavity-backed slot (SICBS) antenna elements are configured for multiple-input multiple-output (MIMO) applications. A wall with a double-layer mushroom structure is positioned in between the four antenna elements. An antenna prototype with a ground plane size of 0.96 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">o</sub> × 0.96 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">o</sub> (λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">o</sub> is the free space-wavelength at 2.4 GHz) demonstrates an enhanced interelement isolation of 16 dB for parallel-directed antenna element pairs, while the isolation of the orthogonally directed antenna element pairs remains unchanged over the operating bandwidth (|S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> | <; -10 dB) of 2.396 -2.45 GHz. With the enhanced isolation larger than 42 dB between each antenna element pair, the envelope correlation coefficient (ECC) is lower than 0.02 across the operating bandwidth. The simulated and measured results validate the good MIMO diversity performance of the proposed antenna system.

A compact multiband pattern diversity antenna for Multiple input multiple output (MIMO) applications is being proposed. The pattern diversity antenna is designed for 2.6 GHz LTE, 3.5/5.5 GHz WiMax, 3.3 GHz MIMO and 5.2 GHz WLAN applications for mobile devices. The compact size of the MIMO antenna (41.05 × 21.1 mm) is due to having compact individual monopole antennas each of dimension 17.5 × 10 mm. A T-shaped and inverted L-shaped stub in the ground plane reduces mutual coupling due to near field whereas slots introduced in the ground plane prevents current to flow through the common ground plane. The important characteristics of MIMO antenna like diversity gain and envelope correlation coefficient have also been presented. Measured and simulated radiation patterns presented show that the MIMO antenna proposed provide pattern diversity.

In this proposal, an advanced integrated multiple‐input multiple‐output (MIMO) antenna system has been presented for next generation 5G‐NR, high speed WLAN and X‐band communications. The four radiators having comb‐shaped geometry at the top edge are positioned orthogonally with each other. An adequate gap is maintained between the radiating ports of MIMO antenna to lower down the mutual coupling. A small fractal geometry is engineered at the bottom corners of the patch to receive size miniaturization, wide band performance and manufacturing advantage. In similar fashion, thin slots are introduced to excel the isolation. The ultrawide band response (1.6 GHz–11.35 GHz) could be achieved by introducing partial ground plane underneath each radiator. A commercially available Flame Retardant 4 substrate was utilized. The individual ground structures are interconnected using thin conducting strips, which play a dynamic role in system performance by providing high isolation between the MIMO elements. The proposed MIMO system is analyzed and confirmed based on various antenna responses such as diversity gain (DG) (&gt;9 dB), mean effective gain (MEG) (−6 to −8 dB), channel capacity loss (CCL) (&lt; 0.4 bits/s/Hz), and envelop correlation coefficient (ECC) (&lt; 0.002 abs). The received reflection coefficient values from the MIMO antenna are compared with actual values. Both the responses are closely aligned with each other. This research supports SDG 9, SDG 11, and SDG 7 by advancing innovative wireless communication infrastructure, enabling sustainable and resilient smart city connectivity, and indirectly promoting energy‐efficient network operations through high‐isolation and efficient antenna design.

In this work, a new design of wide‐band multiple‐input multiple‐output (MIMO) antenna with improved isolation and dual‐band rejection is proposed for wireless systems operating over the entire ultra‐wide‐band (UWB), X‐band, and Ku‐band (3–18 GHz). The proposed four‐element UWB‐MIMO antenna is fabricated on Rogers RT/Duroid‐5880 substrate with dimension of 73 × 73 × 0.79 mm3. It achieves high isolation (&gt;20 dB) between antenna elements without using any decoupling structures. In order to prevent interference problems from nearby WiMAX (3.3–3.8 GHz) and WLAN (5.1–5.8 GHz) systems, a C‐shaped stub is embedded in the radiating patch and a pair of U‐shaped parasitic strips is inserted beside the feed line in the single element design. The effectiveness of the proposed design is demonstrated by investigating measurement and simulation results, and comparing them with other existing designs. The results show that the proposed design has an input reflection coefficient &lt;−10 dB, a mutual coupling &lt;−20 dB, and an omnidirectional radiation pattern across the bandwidth of interest (3–18 GHz) excluding the two rejected bands. Also, the proposed design exhibits high diversity performance in terms of envelope correlation coefficient (ECC &lt;0.0015) and channel capacity loss (CCL &lt; 0.3 bits/s/Hz). This reveals the effectiveness of the proposed design in wide‐band wireless applications such as satellite communications and microwave medical imaging.

A compact 4 × 4 reconfigurable MIMO antenna design with adjustable suppression of certain frequency bands within the UWB frequency range

In this paper, we propose a compact Multiple Input Multiple Output (MIMO) antenna system with high isolation for wireless applications in 5G connected devices. This MIMO antenna system with the size of 92 × 88 mm2 consists of two elliptical antennas symmetrically arranged next to each other. Two decoupling methods which are neutralization and Defected Ground Structure (DGS) are applied to ensure diversity of the proposed MIMO antenna. The single and MIMO antennas are simulated and analyzed then fabricated and measured. A good agreement between measurements and simulations is obtained. These configurations, dedicated to covering the 3.4 GHz band ‐3.8 GHz, have shown very satisfactory performances more than ‐30 dB in terms of reduction of mutual coupling between the antennas constituting our system. MIMO diversity parameters, such as Envelope Correlation (ECC), Diversity Gain (DG), and total efficiency, are also studied for each proposed MIMO system. Thus, results demonstrate that our two proposed antenna configurations are very suitable for 5G MIMO applications.

A dual-mode, dual-port pattern diversity antenna is presented for 2.45-GHz wireless body area networks. This antenna provides multiple radiation patterns as desired for both on- and off-body applications, namely an omniazimuthal radiation pattern directed along the body and a broadside radiation directed away from the body, respectively. This was achieved by exciting the fundamental TM11 mode in a classical circular patch antenna for off-body radiation and the TM01 mode in another circular patch antenna for on-body radiation, which was enforced by using a short circuit between the patch and the ground plane. The two antenna prototypes were finally stacked together into a single package, and the feed positioning had been optimized to offer negligible coupling between the two antenna ports that excite the two modes. The antenna performance has been evaluated in proximity to the body and found to be quite stable, compared to the performance in the free space. Moreover, the diversity performance of the antenna has also been evaluated in the form of an envelope correlation coefficient (ECC) and a diversity gain (DG). The ECC has been observed to be close to zero with a corresponding DG close to 10 dB at 2.45 GHz. This also suggests the suitability of the proposed antenna for diversity and multiple-input–multiple-output systems.

In this paper, 4 × 4/8 × 8/10 × 10 multiple input multiple output (MIMO) antenna systems composed of co-located self-neutralized antenna pairs are proposed to operate at 4.8-5.0 GHz (part of N77 band) for the fifth-generation (5G) communication applications. The proposed antenna pairs consist of a loop antenna and a monopole antenna, co-locating together with a compact size of 6.7 × 15.5 ×3.08 mm 3 . Meanwhile, the co-located design can miniaturize 50% of the antenna size, which is quite significant for practical mobile applications with limited space environment. In addition, the adoption of the self-neutralization technique between the co-located loop antenna and the monopole antenna contributes to a satisfactory isolation with better than 25/20/16.5 dB for the 4 × 4/8 × 8/10 × 10 MIMO systems respectively. Analysis of the isolation improvement is also discussed in this study. Moreover, the antenna pairs are able to generate complementary radiation patterns, enabling the envelope correlation coefficients (ECC) between the antennas to be less than 0.1. Also, efficiencies of the MIMO antenna system achieve up to 60% as there is no external decoupling structure deteriorating the radiation performance of the proposed antenna pairs. Finally, a 4 × 4 MIMO antenna system prototype is fabricated and measured to verify its prospect for 5G MIMO applications.

A compact printed ultrawideband (UWB) multiple-input multiple-output (MIMO)/diversity antenna system (of two elements) with a size of 35 × 40 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> operating at a frequency range of 3.110.6 GHz is proposed. The wideband isolation can be achieved through a tree-like structure on the ground plane. The effectiveness of the tree-like structure is analyzed. Measured S-parameters show that the isolation is better than -16 dB (-20 dB in most of the band) across the UWB of 3.110.6 GHz. The radiation patterns, gain, and envelope correlation coefficient are also measured. The proposed antenna is suitable for some portable MIMO/diversity applications.

SummaryA two‐port multiple‐input‐multiple‐output (MIMO) antenna system operating in the mm‐wave band for 5G applications is presented. The two elements of MIMO structure are separated from each other by 19 mm (1.9 ) and excited by microstrip feed. The MIMO elements are circular patches with round cuts at the edges to improve impedance bandwidth. Quadrilateral slot in the ground plane is designed to improve the radiation characteristics of the radiating element having size 18 0.8 mm3. The MIMO design is simulated through CST. The proposed antenna works in 27–29 GHz range, providing a potential bandwidth of 2 GHz. Furthermore a gain is improved from 8.2 to 8.75 dB and efficiency increase from 85% to 88% and high isolation of 64 dB is achieved by placing 4‐elements of metamaterial with size 4.5 18 mm2 in the middle of two circular monopole antennas. The metamaterial gives us a band stop response and act as decoupler and enhance the isolation to reduce mutual coupling. By analyzing the radiation characteristics of the proposed design, in term of reflection coefficient, surface currents, reduced mutual coupling, suitable gain, envelope correlation coefficient (ECC), diversity gain (DG) and radiation pattern, the recommended antenna can be considered a good candidate for 5G applications.

This paper describes a novel design of co-located antennas system for ultra-wideband (UWB)- Multiple-input multiple-output (MIMO) applications. The antennas system is basically comprised of two patch elements integrated together on a single substrate. The antenna functions efficiently over the frequency range for UWB systems i.e. 3.1–10.6 GHz. The important parameters to evaluate the performance like return los, radiation patterns, mutual coupling, and correlation coefficient have ben simulated to ensure the operability of the system for UWB and MIMO in the same time. The proposed antennas system, designed with FR4 substrate of dimensions 30×68 mm, is compact, easy to manufacture and low-cost.

In the 5G system, multiple-input multiple-output (MIMO) antennas for both transmitting and receiving ends are required. However, the design of MIMO antennas at the 5G upper band is challenging due to the mutual coupling issues. Many techniques have been proposed to improve antenna isolation; however, some of the designs have impacts on the antenna performance, especially on the gain and bandwidth reduction, or an increase in the overall size. Thus, a design with a detailed trade-off study must be implemented. This article proposes a new C-shaped parasitic structure around a main circular radiating patch of a MIMO antenna at 16 GHz with enhanced isolation features. The proposed antenna comprises two elements with a separation of 0.32λ edge to edge between radiation parts placed in a linear configuration with an overall dimension of 15 mm × 26 mm. The C-shaped parasitic element was introduced around the main radiating antenna for better isolation. Based on the measurement results, the proposed structure significantly improved the isolation from −23.86 dB to −32.32 dB and increased the bandwidth from 1150 MHz to 1400 MHz. For validation, the envelope correlation coefficient (ECC) and the diversity gain (DG) were also measuredas 0.148 dB and 9.89 dB, respectively. Other parameters, such as the radiation pattern, the total average reflection coefficient and the mean effective gain, were also calculated to ensure the validity of the proposed structure. Based on the design work and analysis, the proposed structure was proven to improve the antenna isolation and increase the bandwidth, while maintaining the small overall dimension.