Semi-Elliptical UWB MIMO (S-EUM) Antenna with Stairway Decoupling Structure with Time-Domain Analysis

This paper presents two planar UWB MIMO antenna arrays designed from a compact novel CPW fed UWB antenna. The first MIMO antenna is made with lateral placement of the two proposed UWB antennas and second MIMO antenna is made with orthogonal placement of two UWB antennas and both MIMO antennas covers the entire UWB frequency band. The first MIMO antenna with lateral placement operates in frequency range from 2.7 GHz to 12.5 GHz and second MIMO antenna with orthogonal placement of antennas operates in 2.8 GHz to 13.1 GHz band. The designed MIMO antennas have volume of 54 × 30 × 1.6 mm3 for lateral placement and 61 × 30 × 1.6 mm3 for orthogonal placement. Both antennas have satisfactory performance in terms gain, radiation pattern, return loss, voltage standing wave ratio, envelope correlation coefficient and diversity gain for UWB MIMO application.

This article presents a multi-radio antenna system for Cognitive Radio (CR), NB MIMO (5G, WLAN), and UWB MIMO applications by combining independent antennas into a single system. The proposed multi-radio antenna system comprises three independent antennas: the CR antenna system, which consists of a UWB sensing radiator and two narrow band communication antennas; the UWB MIMO antenna system, which comprises a two-element UWB MIMO antenna; and the NB (5G, WLAN) NB antenna system, which consists of a two-element NB antenna. The UWB radiator functions over a bandwidth of 3–12 GHz for CR sensing and UWB MIMO operations, while the NB antennas operate at 3.3, 3.5, 5, 5.5, and 8 GHz for CR communication and NB MIMO communication. Mutual coupling between MIMO radiators is achieved by placing the radiators orthogonal to each other and a parallel line stub. The reflection coefficient, gain, efficiency, and radiation pattern of an antenna were studied. Furthermore, the MIMO performance of UWB MIMO and NB MIMO antenna systems is evaluated using MIMO parameters such as mutual coupling, envelope correlation coefficient, Total active reflection coefficients (TARC), and channel capacity loss (CCL).

Highly selective multiple-notched UWB-MIMO antenna with low correlation using an innovative parasitic decoupling structure

In this article, we present a double side highly isolated triple band-notched UWB MIMO antenna for short-range wireless communication applications. The proposed MIMO antenna design provides a UWB band with the notched band at the IEEE INSAT C band satellite communication and WLAN band (4.6–5.9 GHz), the X band uplink and downlink satellite communication (7.70–8.43) and (10.3-10.98 GHz). It has double side placement of polygon-shaped radiating elements, and an inverted L-shaped stub to obtain high isolation between radiating elements. The proposed antenna has a size of 18 × 28 mm2, which operates from 3 to 12 GHz. The antenna characteristics such as isolation between radiating elements, S11/S22, gain, and radiation characteristics are studied. The proposed MIMO antenna has isolation of >19 dB, 0-7.5 dBi peak gain and almost radiation pattern over the entire operating frequency band with pattern diversity. Furthermore, MIMO diversity performance was investigated using an ECC, diversity gain, multiplexing efficiency, TARC, and CCL. The proposed UWB MIMO antenna has very low ECC of 0.0025, and DG of >9.9, over the entire operating band (3-12 GHz). Also, the real-time indoor short-range communication capability of the proposed MIMO antenna demonstrated by using the NI 802.1 framework

In this paper, a bi-directional UWB MIMO antenna is presented and investigated for superior UWB MIMO performance. The MIMO antenna elements are proved to have a typical impedance matching and directional radiation pattern over the bandwidth 3.9–10.6 GHz. The MIMO antennas have a very low mutual coupling by using efficient DGS. The MIMO antennas are evaluated for perfect MIMO performance. Results confirm that the envelope correlation coefficient (ECC) is almost lower than 0.01 over the UWB bandwidth which guarantees independent transmission/reception through MIMO system sub-channels. Moreover, spatial diversity and spatial multiplexing are proved through better than 9.8 dB diversity gain and 90% multiplexing efficiency. All simulated results are confirmed by measurements.

Adaptive Neuro-Fuzzy Inference System approach in bandwidth and mutual coupling analyses of a novel UWB MIMO antenna with notch bands applicable for massive MIMOs

High isolation band-notched via-fed MIMO antennas are proposed for UWB systems. The MIMO antennas consist of two via-fed monopole UWB antennas which share a common area connecting to the radiators. Four symmetrical fish-bone shaped slits are etched on the common area and optimized by MOEA/D-DE to achieve isolation of 22dB. Moreover, three resonators optimized by MOEA/D-DE are added to achieve sharp roll-off notched band or three notched bands. For demonstration, the first design is band-notched UWB MIMO antennas with sharp selectivity. Both simulation and measurement show that isolation higher than 22dB and a second-order notched band of 5.15-5.85GHz are achieved in the UWB band. With the proposed antenna and design technique, the second design achieves high isolation and three notched bands (3.3-3.6GHz, 5.15-5.85GHz, 7.25-8.4GHz) for UWB MIMO antennas.

This investigation uses the Genetic Optimization Method to convert a wide-band MIMO antenna into a UWB (3.1GHz–10.6 GHz) MIMO antenna. Initially, a 22 × 42, mm2 wideband 2X2 MIMO antenna was designed using commercial Flame Retardant-4 material. The structure of the antenna patch was designed using half-circular forms on the half-ground plane. The designed MIMO antenna operates throughout a large frequency range of 4.8–9.8 GHz. While it was successful in achieving broad band characteristics, this MIMO antenna was unable to reach ultra-wide band characteristics. The MIMO antenna was operated in UWB ranges by a parametric study, which indicated that the resonating characteristics can be significantly modified by inserting a rectangular slot into the ground plane. Throughout the operational range, it was important to be concerned about improved gain and good isolation. Accordingly, optimization was carried out in order to accomplish the essential, multi-objective goals. The difficult multi-objective design goal is now reduced to an optimization challenge by means of genetic algorithm based random search. One of the performance goals that this optimization strategy aimed to fulfil was an increase in isolation to –20 dB across the entire Ultra-Wideband, with S11 being below –10 dB from 3.1 to 10.6 GHz. It is recommended to randomly select the parameters from their respective ranges for this work. This led to the selection of an optimizer based on random searches. In the operating range, the UWB has a respectable gain of 4 dB to 6 dB and increased isolation to –20 dB, according to the genetic algorithm optimizer’s execution of the predefined multiple-objective task.

In this paper, a dual port reconfigurable band-notched UWB MIMO antenna is presented to reduce the interference with WLAN and WiMAX applications. The suggested MIMO antenna is designed on RO 4350 substrate with partial ground plane for achieving the UWB frequency range with a band-notch at 5.4 GHz to avoid interference with WLAN application. An isolation structure is merged with the partial ground plane to achieve an isolation better than 17 dB between the two elements. Two pairs of lumped capacitors are embedded in the band stop resonators for achieving frequency reconfigurability by shifting the band stop behavior from 5.4 GHz to 3.5 GHz for interference mitigation with WiMAX application. The suggested MIMO antenna is experimentally fabricated and tested to validate the obtained simulated results since a good consistency between both results is achieved not only the impedance characteristics, but also the radiation and diversity outcomes. The new contribution of presented MIMO antenna is evident when it compared with state-of-the-art antennas which confirms the ability of the fabricated model to be utilized for various wireless communication applications in the microwave frequency range.

This manuscript proposes a design of UWB MIMO antenna with different mutual coupling reduction techniques. Initially, single element UWB antenna is designed on FR4 substrate with the dimension of 30 mm × 30 mm × 0.8 mm and fed by micro-strip line. It consists of rectangular-shaped radiator with two slits in the bottom edges in the front plane and modified partial ground in the rear plane. The designed unit element forms the fundamental structure for the MIMO antenna. The dimension of the quad element MIMO antenna is 65 mm × 65 mm × 0.8 mm. Then, the different types of mutual coupling reduction techniques such as decoupling structure, neutralization line technique, and stubs in the ground plane are implemented to reduce the coupling between the radiators. The proposed MIMO antenna produces envelop correlation coefficient (ECC) < 0.02, diversity gain (DG) higher than 9.7 dB, and it also achieved a good impedance bandwidth between 2.7 and 10.5 GHz. The ground plane stub technique produces better results in terms of percentage bandwidth and ECC reduction. A comparison between various decoupling techniques and their effects on the antenna performance are analyzed.

In this paper, for the proposed UWB MIMO Antenna, spectral efficiency is combined with improved mutual coupling. Proposed UWB MIMO antenna modified with a wideband neutralization line. By using decoupling method, the UWB MIMO antenna covers the band of 36.5GHz .The provided wideband neutralization line is not important to be put on the copper ground and applied between two MIMO elements in the clearance area of antenna. Here the antenna size is 35x33mm2. MIMO antenna is applied in portable devices. The parameters like S parameter, realized gain, radiation pattern and total efficiency are compared using different simulations. The effectiveness of the applied wideband line of neutralization is authenticated by these simulations.

Two compact coradiator multiple-input-multiple-out (MIMO) antennas operating in the UWB frequency band with dual polarization are proposed. Different from traditional MIMO antennas, the radiator is shared by two antenna elements, which greatly reduce the overall size of the MIMO system. High isolation between the two antenna elements is achieved by etching a T-shaped slot in the radiator and extending a stub on the ground. Dual polarization can be realized by exciting the pentagonal radiator with perpendicular feeding structure. The simulated results of current and electric-field distribution show the dual-polarization characteristics of the diversity system. Besides, a four units UWB MIMO antenna is also proposed. Furthermore, the diversity characteristics of mean effective gains (MEGs) and diversity gain (DG) are also studied. The simulated and measured results demonstrate that the UWB-MIMO antenna has good impedance matching, isolation and dual polarization characteristics.

Abstract: UWB MIMO antenna loaded structure Mutual coupling between the four radiating elements is obtained to be less than - 25 db. The patterns of radiation are stable over the operating range and a peak gain of 4.5 dB is obtained at 7.5GHz and Return loss is obtained less than 10dB. Simulation is conducted using HFSS simulation tool and printed on a 30 X 30 X 1.6 mm3 FR4 material. 4 linear SRR structures are used between adjacent elements to ensure good isolation. MIMO antenna with grounded stubs and fractal geometry are used to improve isolation and to achieve wide band phenomena. UWB-MIMO antenna using to achieve better isolation. The UWB MIMO 4-port fractal antenna combines the characteristics of ultra-wideband operation, multiple input multiple output capability, four-port configuration for simultaneous data streams, and a fractal antenna design for wide bandwidth and compact size. This makes it suitable for high-speed, reliable communication in applications requiring UWB technology, such as high-speed data transfer, localization, and radar systems. By integrating a copper rectangular plane between ports, interference and crosstalk are minimized, enhancing the antenna's capability to handle multiple input and output signals efficiently. This innovative design approach not only improves isolation but also contributes to the antenna's overall effectiveness in various communication applications.

A miniaturized ultra-wideband multiple-input multiple-output (UWB MIMO) two-port antenna with high isolation based on FR4 is designed in this article. The size of the antenna is only 18 × 28 × 1.6 mm3. The MIMO antenna consists of two identical antenna elements symmetrically placed on the same dielectric substrate in opposite directions. By loading three crossed X-shaped stubs between two unconnected ground planes, high isolation and good impedance matching are achieved. The working frequency band measured by this UWB MIMO antenna is 1.9–14 GHz, and the isolation is kept above 20.2 dB in the whole analysis frequency band. Good radiation characteristics as well as envelope correlation coefficient (ECC, &lt;0.09), mean effective gain (MEG), and channel capacity loss (CCL) in the passband meet the requirements of the application, which can be applied to the UWB wireless communication system. To verify the applicability of the proposed method for enhancing the isolation between antenna elements, the two-port antenna structure was extended to a four-port antenna structure. In the case of loading the X-shaped stubs to connect to the ground plane, the isolation of the antenna is maintained above 15.5 dB within 1.7–14 GHz.

In this paper, we introduce a four-port self-isolated UWB MIMO antenna for diversity applications. First, we have developed a basic radiating element of the proposed antenna in four stages of design, where patches of geometrically different shapes were added at each stage to arrive at the final radiator form. The antenna was designed on an FR-4 substrate with a compact size of 28 × 28 × 1.6 mm3. A tapered microstrip feeding was employed to enhance the antenna’s impedance matching. An orthogonal arrangement of the four radiators was adopted to mitigate the mutual coupling between them, avoiding the use of a separate isolation structure. A prototype was built and measured with a close agreement between the experimental and simulated results. The MIMO antenna performed well in the entire frequency spectrum of 3.1–10.6 GHz, with an isolation better than 20 dB. The measured envelope correlation coefficient (ECC) was less than 0.001, the diversity gain (DG) was greater than 0.99 dB, and the total active reflection coefficient (TARC) was less than −10 dB. The performance of the proposed antenna design was compared with existing designs. The comparison showed that the proposed quad-element UWB MIMO array is compact, has good isolation and diversity performance compared to existing designs, and is well-suited for wireless diversity applications.