Proposed Ultra-wideband Multiple-input Multiple-output Antenna Research Articles

Four‐radiator ultra‐wideband multiple‐input multiple‐output antenna with high performance and dual‐band rejection features for high‐speed communications

SummaryWe are discussing a compact, four elements with high‐performance ultra‐wideband (UWB) multiple‐input multiple‐output (MIMO) antenna with dual band‐notched traits. The antenna has a partial ground plane and the radiator has truncation to enhance the matching through the frequency range 2.5–12 GHz. The coupling between ports was reduced by assorting the elements of the antenna in an orthogonal manner and applying four stubs between them. The proposed antenna achieves two band‐notched characteristics by introducing a T‐shaped strip etched in the radiating elements and adding an open‐loop resonator near the feeding line. The results, which were simulated and measured, indicate that the proposed design achieved a wideband from 2.5 to 12 GHz with two band‐notched characteristics within 3.3–3.6 GHz (WiMAX implementations) and within 5.2–5.8 GHz (Wireless Local Area Network [WLAN] applications). As well as, the proposed antenna has high isolation >20 dB and a low‐envelope correlation coefficient <0.005 through the band except for the band notches. These outcomes demonstrate the adequacy of the proposed UWB MIMO antenna for UWB MIMO applications.

Isolation Enhancement between Ports of a Compact Ultra-wideband MIMO Antenna

In this paper, a novel compact multiple-input multiple-output (MIMO) antenna with enhanced port isolation is proposed for ultra-wideband (UWB) applications. The UWB MIMO antenna contains two coplanar annular monopoles etched on the front side of the FR-4 substrate. The dielectric substrate has a relative permittivity of 4.4 and a size of 80 mm × 40 mm × 1.6 mm. The irregular ground is printed on the back side of the substrate. In order to enhance the port isolation between the two monopoles, the expanded ground is exploited in the proposed design. In addition, the ground is etched with some slots to achieve good impedance matching. Both the simulated and measured results show that the proposed antenna achieves good impedance matching as well as high port isolation over the entire UWB band. Moreover, the proposed antenna has good spatial diversity characteristics. In summary, the proposed UWB MIMO antenna can be well applied to the ultra-wideband wireless communication system.

Miniaturized inverted ultra‐wideband multiple‐input multiple‐output antenna with high isolation

For the ultra-wideband (UWB) transmission requirements in wireless communication systems and better miniaturization of mobile terminal antennas, a compact UWB multiple-input multiple-output (MIMO) antenna with higher isolation between units is proposed. The MIMO antenna consists of two semi-circular antenna units and a defective ground structure. By improving the structure of the ground plane, the antenna units are placed upside down by taking advantage of the inherent directional radiation characteristics of the antenna units, thereby achieving higher isolation. The proposed antenna size is 15 × 22 × 1.6 mm3. The measurement results show that the proposed UWB MIMO antenna satisfies the port reflection coefficient S11 < −10 dB in the 3.4–12.9 GHz band, and the isolation is all greater than 25 dB, which has high isolation. The allowable limit of the envelope correlation coefficient ensures good MIMO performance, which can meet the requirements of UWB wireless communication in practical engineering applications.

Design and analysis of a compact UWB MIMO antenna incorporating fractal inspired isolation improvement and band rejection structures

This paper numerically proposes and experimentally investigates a compact coplanar waveguide fed two element ultra-wideband (UWB), multiple-input–multiple-output (MIMO) antenna array accompanying peak isolation and triple band notch mechanism. The proposed antenna consists of two identical printed monopole elements along with the incorporation of multiple 2nd order Hilbert defects in the ground structure and proposes to incorporate three different mechanisms to reduce the electromagnetic interference of the UWB antenna with existing narrowband systems. The measured impedance bandwidth for the intended antenna ranges from 2.7 GHz to 11.22 GHz. The incorporation of notch mechanisms provides interference suppression at the C-band (3.7–4.2 GHz), WLAN (5.15–5.825 GHz), and X-band communication (7.9–8.4 GHz). The overall size of the intended UWB MIMO antenna is 30.75 mm × 37.80 mm. Moreover, the diversity parameters of the proposed UWB MIMO antenna are numerically calculated and empirically investigated, these calculations and investigations depicts high diversity performance. It is noteworthy to observe that the spacing between the elements is staggeringly reduced to 2 mm. The concurrence among the diverse numerical and experimental outcomes supports the candidature of the suggested layout for portable UWB as well as UWB MIMO systems.

An Ultra-Wideband Rectangular Dielectric Resonator Antenna With MIMO Configuration

A Coplanar waveguide (CPW) fed multi-permittivity and stair shaped dual rectangular dielectric resonator antenna (RDRA) has been designed for ultra-wideband (UWB) applications in multiple-input multiple-output (MIMO) configuration. Isolation improvement has been obtained by means of modified CPW feeding and a metallic diagonal stub in the proposed structure. The simulated results have been validated by prototype designing and performing measurements. The electrical size of the proposed antenna configuration is $1.12\lambda _{0}\times 1.12\lambda _{0}\times 0.25\lambda _{0}$ . The measured input impedance bandwidth of the antenna is 153.6% (1.6-12.2 GHz) with a minimum of 25 dB isolation between the radiators in the operating band. Measured results illustrate the satisfactory performance of proposed UWB MIMO antenna with a low envelope correlation coefficient and low mutual coupling throughout the desired frequency range.

Utilization of Shorted Fractal Resonator topology for high isolation and ELC resonator for band suppression in compact MIMO UWB antenna

A low profile modified Koch fractal shaped boundary, ultrawideband (UWB) multiple input multiple output (MIMO) antenna is presented. The radiators are elliptically tapered from the feed line with triangular shaped loading. The boundaries of the triangular shaped loading are embedded with modified Koch fractal shape to provide improved impedance matching. A band suppression characteristic at 5.5 GHz is incorporated by using an electric inductive capacitive resonator at the back of the substrate. Enhanced port isolation of <−20 dB is achieved by using a Maple leaf fractal structure shorted with ground plane. The proposed UWB MIMO antenna has peak realized gain of 4 dBi, and envelope correlation factor is less than 0.01. Measured results closely resemble the simulated results. Moreover, an equivalent circuit model of the proposed structure is extracted and compared with the em simulation result, which are in good agreement.

Development of MIMO antenna with decoupling structure for ultra-wideband application

This paper presents the design of adouble-sided Multiple-Input Multiple-Output (MIMO) antenna with a decoupling structure for Ultra-WideBand (UWB) applications. The proposed antenna consists of four square radiating elements printed on FR-4 substrate with partial slotted ground. The substrate consists of two sides and each side are consisting of two slotted partial ground and two square radiator antennas. The elements of the front side are orthogonal to the elements of the back side because it was to increase the isolation of the antenna. The front and back sides of the substrate were also presented with the decoupling structure to avoid the mutual coupling of each antenna. The results of simulated and measured of the proposed UWB MIMO antenna are observed and analyzed. The objective of the UWB MIMO antenna was achieved that large bandwidth of return loss below than -10 dB from 3.3 GHz to 11GHz with an insertion loss lower than -20 dB within the required frequency band. The proposed MIMO antennas exhibits a nearly Omni-directional radiation pattern with average gain value 4.36 dBi.

A CPW-fed UWB MIMO antenna with integrated GSM band and dual band notches

This article presents a coplanar waveguide fed global system for mobile communications band integrated ultra wide band (UWB) multiple input multiple output (MIMO) antenna with single and dual notch band characteristics. The novelty of the antenna lies in its design as all the unit cells of the proposed UWB MIMO antenna structure are orthogonal to each other therefore the additional isolation elements responsible for achieving high isolation are not required consequently making proposed antenna design simple and easy to fabricate. In this context, 2 MIMO systems have been designed. The first MIMO system is consisting of a dual port antenna whereas the second MIMO system is a printed quad port antenna; further single and dual notch band are achieved in the proposed multi-port MIMO antenna. The antenna shows pattern diversity throughout the impedance bandwidth range. The gain of the antenna varies from 4 to 8.48 dBi. The 2 band notches are achieved at 4.8 and 7.7 GHz in the UWB range. The proposed antenna is fabricated and it is found measured results are in good agreement with simulated results.

Mutual coupling reduction with a wideband planar decoupling structure for UWB–MIMO antennas

AbstractA new planar multiple-input–multiple-output (MIMO) antenna for ultra wideband (UWB) applications is presented. The proposed antenna operates over the frequency band from 3.1 to 10.6 GHz and it consists of two identical circular monopoles on an FR4 substrate. The wide isolation is achieved through a novel planar decoupling structure that is being inserted between the dual antennas. Moreover, a center slot is etched on the common ground to further increase isolation. The effectiveness of the decoupling structure is analyzed, and performance study has been performed to investigate the mutual coupling reduction. A good isolation of more than 31 dB has been achieved through the entire UWB band (more than 12 dB improvement over the reference antenna). The proposed UWB antenna with and without the wideband decoupling structure has been investigated and verified both numerically and experimentally. The measurement results of the proposed UWB–MIMO antenna are in good agreement with the simulation results. The proposed UWB antenna has been compared with previous works regarding antenna size, geometric complexity, bandwidth, and isolation level. The proposed antenna has some outstanding characteristics such as a geometric simplicity, compact size, broad bandwidth, and low correlation which give the antenna an excellent diversity performance and a good candidate for UWB applications.

Tapered Fed Compact UWB MIMO-Diversity Antenna With Dual Band-Notched Characteristics

In this paper, a compact design of multiple-input multiple-output (MIMO) Antenna with dual sharply rejected notch bands for portable wireless ultrawideband (UWB) applications is presented and experimentally investigated. The proposed UWB MIMO Antenna has a compact size of 18 mm $\times$ 34 mm. The tapered microstrip fed slot Antenna acts as a single radiating element with inverted L-shaped slits to introduce notches at wireless local area network and the IEEE INSAT/Super-Extended C-bands. The mutual coupling of less than −22 dB is achieved over the entire operating band (2.93–20 GHz). At the center of notched band, the efficiency of the Antenna drops that indicates a good interference suppression performance. The performance of the MIMO Antenna in terms of isolation among the ports, radiation pattern, efficiency, realized gain, envelope correlation coefficient, mean effective gain, and total active reflection coefficient is studied.

Compact band-notched UWB antenna for MIMO applications in portable wireless devices

A compact 5.5 GHz band-notched ultra-wideband (UWB) 2-element antenna with high isolation for multiple-input multiple-output (MIMO) portable wireless devices in wireless personal area network (WPAN) application is proposed. The MIMO antenna is designed for 3.1–10.6 GHz range on Neltec substrate with compact dimension of 43 × 20 mm2 and is tested experimentally. For the rejection band at 5.5 GHz, a slot of length 1.0 λ is etched into the radiator. Simple structure, i.e., receded steps at ground are used to improve isolation by 3 dB between two UWB antennas. The simulated and measured results show |S11| ≤ −10 dB and |S21| ≤ −20 dB in most of the frequency range excluding the reject band at 5.5 GHz in UWB range. The measured, simulated and calculated results show that the proposed UWB MIMO antenna is a good candidate for UWB MIMO systems. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1390–1394, 2016

Compact MIMO Slot Antenna for UWB Applications

A compact four-element multiple-input–multiple-output (MIMO) antenna for portable wireless ultrawideband (UWB) applications is presented in this letter. The proposed UWB MIMO antenna has the compact size of $ 42 \times 25 ~\hbox{mm}^2$ . The microstrip-fed stepped-slot antenna acts as a single UWB antenna element. The UWB antenna covers the wide frequency band from 3.1 to 12 GHz. High isolation ( $ \geq 22~\hbox{dB}$ ) is achieved between the UWB antenna elements without any decoupling network. It is due to inherent directional radiation properties of slot antennas (SAs) and their asymmetrical placements. The measured impedance bandwidth of UWB MIMO antenna is from 3.2 to 12 GHz with the isolation better than 22 dB over the entire UWB spectrum. The envelope correlation coefficient (ECC) as well as channel capacity loss (CCL) are investigated, and they are within their acceptable limits.

An Ultrawideband MIMO Antenna With Dual Band-Notched Function

A new technique to achieve both good isolation and dual band-notched functions for ultrawideband (UWB) multiple-input-multiple-output (MIMO) antennas was developed. The proposed antenna consists of the radiation patch connected through a via with the strip placed beneath the patch. The strip not only provides another coupling path, but also serves as the impedance transformer, resulting in good isolation (S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</sub> <; -15 dB) and dual band rejection at WiMAX (3.4-3.7 GHz) and WLAN (5.15-5.35 and 5.725-5.825 GHz) over the UWB system operation (3.1-10.6 GHz). Without decoupling element or resonator, which is often placed between the antennas to acquire good isolation or band rejection, the proposed UWB MIMO antenna requires an individual antenna element size of only 11.2 12 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> (0.12λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ×0.11λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> )and overall MIMO antenna size of 30 40 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> (0.31λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ×0.41λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ). The edge-to-edge separation between antennas is , and separation between feeds is 0.175λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> at 3.1 GHz. Detailed investigations of the parameters were performed, and the experimental results agree closely with the simulation results, demonstrating the feasibility of the proposed method.

Compact Dual Band-Notched UWB MIMO Antenna With High Isolation

A compact dual band-notched ultra-wideband (UWB) multiple-input multiple-output (MIMO) antenna with high isolation is designed on a FR4 substrate (27 × 30 × 0.8 mm3). To improve the input impedance matching and increase the isolation for the frequencies ≥ 4.0 GHz, the two antenna elements with compact size of 5.5 × 11 mm2 are connected to the two protruded ground parts, respectively. A 1/3 λ rectangular metal strip producing a 1.0 λ loop path with the corresponding antenna element is used to obtain the notched frequency from 5.15 to 5.85 GHz. For the rejected band of 3.30-3.70 GHz, a 1/4 λ open slot is etched into the radiator. Moreover, the two protruded ground parts are connected by a compact metal strip to reduce the mutual coupling for the band of 3.0-4.0 GHz. The simulated and measured results show a bandwidth with |S11| ≤ -10 dB, |S21| ≤ -20 dB and frequency ranged from 3.0 to 11.0 GHz excluding the two rejected bands, is achieved, and all the measured and calculated results show the proposed UWB MIMO antenna is a good candidate for UWB MIMO systems.