Dual Antenna System Research Articles

A Compact Multifrequency Broadband Dual-Antenna System With Mutual Coupling Reduction for Wi-Fi 6E Application

A Compact Multifrequency Broadband Dual-Antenna System With Mutual Coupling Reduction for Wi-Fi 6E Application

The design and decoupling of TX/RX antenna with omnidirectional conical beam operating at V band

Abstract In this work, a high isolation transmitter–receiver antenna with omnidirectional conical beam operating at 61.5 GHz is presented. The proposed dual-antenna system consists of a transmitter (TX) antenna and a receiver (RX) antenna with the same structure, composed of a circular metal patch with ring slot and metal shorting vias, fed by a coaxial probe at their respective geometric center. And both antennas are placed on a circular metal platform, positioned symmetrically with each other. To increase the isolation between them, three different decoupling methods are proposed, and the one with an electromagnetic band gap (EBG) structure added in-between shows the most promising decoupling effect, as the surface wave current can be maximally suppressed. The overall size of the antenna system is 2.2552 × π × 0.579 λ 0 3, where λ 0 is the free space wavelength at 61.5 GHz. A prototype of the proposed antenna system with EBG decoupling structure is fabricated and measured, demonstrating that the TX–RX isolation is 57.9 dB at 61.5 GHz, 21.6 dB better than that without decoupling structure, with omnidirectional conical beam radiation achieved at the same time.

Application of switchable 4G/5G dual antenna system for laptops

AbstractThis work investigates a switchable 4G/5G dual‐antenna system designed for laptops. The dual open‐slot antenna structure is straightforward, with a slot width of only 2 mm. Each individual antenna features two different feed sections located in two separate regions between the slots. Port 1 is a direct‐feeding design with 3.6 pF chip capacitance, while Port 2 is only a direct‐feeding design. When Port 1 is excited and Port 2 is terminated to 50‐Ω, the antenna is functional in long‐term evolution (LTE) low‐band (617–960 MHz) and 5G sub‐6 GHz band (3300–5000 MHz). On the other hand, when Port 2 is excited and Port 1 is terminated to 50‐Ω, the antenna is functional in the LTE medium/high bands between 1710 and 2690 MHz. The measured isolation consistently exceeded 30 dB, and the efficiency remained above 48% across the entire frequency range. The calculated envelope correlation coefficients derived from the complex E‐field radiation pattern measurements were consistently below 0.02. These findings indicate that the system is exceptionally well‐suited for applications characterised by integrated metallic environments and a high display‐to‐body ratio.

Low-Cost 3-D Millimeter-Wave Concealed Weapons Detection Using Single Transceiver Affine Synthetic Arrays

The problem of detecting concealed weapons with a low-cost 3-D imaging radar system is addressed. The concept of affine phase center translations to generate a synthetic array is proposed as an alternative to conventional synthetic aperture and multistatic imaging radars. This enables the generation of a synthetic 2-D array with a dynamic dual reflector antenna system and a single transceiver. The dual reflector antenna is composed of a 3-D printed ellipsoidal sub-reflector and a conic main reflector. The phase front of the horn feed is shown to be translated to different locations by controlling the relative positions of the two reflectors. The reflectors are fabricated using a simple protocol that keeps the cost very low but introduces significant phase aberrations. These phase aberrations are corrected by developing a novel geometrical optics based optimized calibration routine. The imaging system is tested using a 76.5–84.5 GHz stepped frequency transceiver in different concealed weapons detection scenarios. As a demonstration, a metallic handgun and a nonmetallic pipe-bomb are concealed on a mannequin which serves as a human surrogate with similar skin reflectivity. At a target distance of 2.8 m the achieved depth resolution and lateral resolution are 2 and 1.5 cm, respectively. The 3-D images constructed using back-projection are of high enough quality to successfully identify the weapons while maintaining the privacy of the individual.

Mutual Coupling Suppression Between Two Closely Placed Patch Antennas Using Higher-Order Modes

This paper presents a novel method for decoupling two patch antennas. Instead of using the TM10 mode of a conventional patch, TM20 mode is utilized as the operation mode of the antenna. By loading stubs at the radiating edge of the patch, the resonance frequency of the TM20 mode is moved down to the same band as the original TM10 mode. Then the mutual coupling between two such patch antennas is suppressed simply by physical placement, even when they are placed extremely close to each other. Without using any extra decoupling elements, isolation is improved by up to 20 dB using this method. Furthermore, this method can also be applied to multi-element multi-input-multi-output (MIMO) array and dual-antenna system with different operating bands. The proposed method is verified with three different application scenarios, including a 2-element MIMO array, a 2-antenna system with adjacent operating bands, and a 4-element MIMO array. Reasonable agreements between simulated and measured results can be observed, showing the advantages of simple structure, low cost, high isolation, and good radiation performance.

Design of Highly Isolated Dual-Antenna System for Handset in Different Scenarios

To mitigate the interference between antennas working at the same frequency band but for different protocols, high isolations are in demand. In this paper, a dual-antenna system, operating for the WLAN/Bluetooth protocols, has been designed on the top part of the mobile handset frame based on the correlation method. A high isolation of above 30 dB is achieved in both free space and the hand-loading scenario. The first antenna is chosen on the corner of the frame for easy excitation of the modes. Afterwards, the location of the second port, which is least correlated with the first antenna, is calculated and determined from MATLAB, leading to low coupling with the first antenna in free space. To maintain the high isolations in the hand-loading scenario, the handset is slightly modified with one more breaking on the frame. The antennas can also be decoupled when the correlation method is directly applied to the hand-loaded antennas. The proposed dual-antenna system has been fabricated and measured, exhibiting good performances in different scenarios.

Compact dual-band MIMO monopole dual-antenna system for 5G laptops

AbstractThe study aimed to present a dual-band 5G multi-input multi-output monopole dual-antenna system, which was configured on the upper edge of the display ground plane for laptops. The dual-antenna unit is a 29 × 2 × 3 mm3three-dimensional structure with two antennas of the same structure and size, consisting of a fed monopole antenna and a shorted monopole antenna. The antennas are arranged 4 mm apart, side by side in the same direction, to form a dual-antenna unit. Such a configuration allows the feeding points of the two antennas to be separated by the shorting point of the shorted monopole antenna, and the shorting point of the low-frequency resonant path (the shorted monopole antenna) of the two antennas to be larger than a quarter of the wavelength of the low frequency with appropriate bending. The strong current will be concentrated near the shorting point of the shorted monopole antenna when the low-frequency mode is excited, and the current flow from the ground to the feeding point of the other antenna will be reduced, achieving the isolation which is better than 10 dB in measurement between the two antennas without adopting any isolation element. The envelope correlation coefficients calculated from the measured complex E-field radiation patterns are all smaller than 0.12, which can cover the 5G dual-band operations of 3300–3600 and 4800–5000 MHz, and the measured antenna efficiencies can reach more than 40%, which are well suited for multiple antenna applications.

A reconfigurable dual port antenna system for underlay/interweave cognitive radio

<span lang="EN-US">An antenna system that is reconfigurable in frequency is presented in this paper as a novel dual port design that serves both undelay and interweave cognitive radio. This 25×40×0.8 mm3 system is composed of two wide slot antennas: the first is designed as an ultra-wideband (UWB) antenna with controllable band rejection capabilities, while the second antenna is reconfigurable for communication purposes. Three slots are etched into the patch of the UWB antenna to obtain band notching in wireless local area network/Xband/International Telecommunication Union bands (WLAN/Xband/ITU) bands which can be controlled by a positive-intrinsic-negative (PIN) diode across each slot. The configuration states of these three diodes are all useable that produces seven band rejection modes plus the UWB operation mode. The second antenna is configured by five PIN diodes to operate either in Cband, WLAN or Xband regions which results in three interweave modes when setting the first antenna for UWB sensing. The design is simulated by computer simulation technology (CST) v.10. S21 results shows good isolation while input reflection coefficient and realized gain results prove system’s scanning, filtering and communication capabilities. This system is new that it gathers the undelay/interweave operation in a single design and when considering its large number of operation modes it looks adequate for many cognitive radio applications.</span>

Dual-functional communication and sensing antenna system

In this article, a dual functional antenna system for communication and sensing applications is designed on a single substrate having a common input port. The main motivation behind the proposed design is to build an antenna system, which can work as an antenna sensor and also can communicate over a fixed band not related to the resonance frequency shifts of the antenna sensor. The dual functionality of the system has been achieved by designing a frequency selective multipath filter (FSMF). The FSMF has an input port and two output ports. Both the communicating and sensing antennas are integrated on the output ports of the FSMF. The FSMF ensures minimum effect of the antennas on each other’s performance. The performance of the antenna sensor is first shown by characterizing different standard substrates with {varepsilon} _r=2.2 to 6.15 and then demonstrated for ice and water detection. The communicating antenna is used for Wi-Fi (2.45 GHz) applications. The simulated and measured results of the dual-functional antenna systems are in good agreement. The proposed design is fabricated on a PCB with {varepsilon} _r=3.5 and tan delta =0.0027 with an overall size of 86.7times 26times 0.8,text {mm}^3.

RF-Access: Barrier-Free Access Control Systems with UHF RFID

Traditional RFID-based access control systems use flap barriers to help manage pedestrian access and block unauthorized staff at any entrance, which requires visitors to swipe their cards individually and wait for the opening of the blocking body, resulting in low-frequency pedestrian access and even congestion in places with large passenger flow. This paper proposes a barrier-free access control system (RF-Access) with UHF RFID technology. The main advantage of RF-Access is that it provides non-intrusive access control by removing flap barriers and operations of swiping the card. The visitors just go across the system without any stay at the entrance. Meanwhile RF-Access performs the authentication, which greatly improves time efficiency and quality of service. RF-Access addresses two key issues of the non-intrusive access control: motion direction detection and illegal intrusion detection. In RF-Access, we first propose a dual-antenna system setup together with a time-slot-based model to monitor users’ moving directions, which is robust to different environmental factors, such as multi-path effects. Afterwards, we use a tag array to detect illegal intrusion in case attackers do not carry any RFID tags. We implement a prototype of RF-Access with commercial RFID devices. Extensive experiments show that our system can detect the moving direction with 99.83% accuracy and detect illegal intrusion with an accuracy of 96.67%.

A Novel UHF-RFID Dual Antenna Signals Combined With Gaussian Process and Particle Filter for In-Pipe Robot Localization

Condition assessment of underground infrastructures such as pipe networks is crucial for aging cities around the globe. Recent development of robotic technologies facilitated application of them in condition assessment of pipe networks. However, there is still a gap for accurate localization technology in pipes due to complexity of the environment. In this letter, we propose a novel ultra-high frequency radio frequency identification (UHF-RFID) technology dual antenna system combined with Gaussian process and Particle filter algorithms to achieve millimeter level localization accuracy. The system is capable of achieving millimeter level accuracy over 50 m of length without an apparent estimation drift. The results were validated through experiments conducted using an extracted water pipe section.

이중 안테나 제어에 따른 유도결합 N₂/NH₃/SiH₄ 플라스마의 전자 및 라디칼 밀도 분포

Low temperature N₂/NH₃/SiH₄ plasma is used to deposit hydrogenated silicon nitride(SiN<SUB>x</SUB>:H). In this process, the main factor influencing the quality of the deposited film is the active species, such as SiH<SUB>x</SUB> and NH<SUB>x</SUB> radicals. In the conventional methods, it was insufficient to explain the correlation between generation of active species and the process parameters. So, a fluid model of 2D axis-symmetry based on dual antenna inductively coupled plasma (ICP) source using N₂/NH₃/SiH₄ gas mixture has been developed for SiN<SUB>x</SUB>:H film deposition. The gas mixture model was comprised of 57 species, 195 chemical reactions and 16 surface reactions. The ratio of input power between independent antenna system affects the electron and SiH<SUB>x</SUB>, NH<SUB>x</SUB> radical generation. And it was observed that the spatial uniformity of electron and radical density increases when the independent input power of dual antenna system is set to 500:500W.

DUAL SUBSTRATE MIMO ANTENNA SYSTEM FOR COGNITIVE RADIO AND AUTOMOTIVE APPLICATIONS

A compact, planar, dual reconfigurable, substrate, multi-band, multiple-input multiple-output (MIMO) antenna system is presented. The proposed MIMO antenna is designed to operate over the entire ultra-wide-band (UWB) frequency band supporting cognitive radio (CR) and automotive applications. The dual-element MIMO antenna is integrated with a radiating element and pure ground plane to operate in two different modes. Two modes of operation are used for the MIMO antenna to sweep the frequency over a wide band especially below 1 GHz. The proposed MIMO antenna covers a wide range of frequency bands from 500MHz~10GHz. The elements of the proposed compact multilayer dual substrate MIMO antenna are placed perpendicular to each other to attain high isolation and polarization diversity which makes the antenna system best suited for CR and automotive applications. The antenna system is developed on dual substrate area of dimensions 58×61×1.6 mm3. The proposed antenna achieves multiband operation with a wide bandwidth of 2GHz within the UWB frequency band.

Octaband WWAN/LTE Dual-Antenna System Decoupled by Two Neutralization Lines with Inductors for Smart Phones

A decoupled octaband WWAN/LTE dual-antenna system occupying a size of 80 mm × 15 mm × 6.8 mm for smart phones is proposed. The proposed antenna system consists of two antenna elements with symmetrical geometry, two neutralization lines (NLs) with embedded inductor, and an inverted-T branch. The two NLs mainly reduce the mutual coupling at the desired lower (704–960 MHz) frequency band, while the inverted-T branch mainly reduces the mutual coupling at the desired higher (1710–2690 MHz) frequency band. The fabricated prototype has a −6 dB impedance bandwidth of 0.3 GHz (0.69–0.99 GHz) and 1.2 GHz (1.66–2.86 GHz) which cover the LTE700, GSM850, GSM900, DCS, PCS, UMTS, LTE2300, and LTE2500 bands. Within these bands, the measured mutual couplings are lower than −10 dB. The measured antenna efficiencies are about 42.6%–60% and 58.3%–78.7% at the desired lower and higher frequency bands, respectively. The diversity performance and the SAR performance are also evaluated.

Miniaturized Dual-Antenna System for Implantable Biotelemetry Application

In this letter, a dual-antenna system with enhanced isolation operating at 2.4-2.48 GHz Industrial, Scientific, and Medical (ISM) band for biotelemetry application is presented. Initially, a miniaturized antenna based on T-shaped resonator and shorting via is developed as a primary antenna element. Then, a compact dual-antenna system of size 0.084 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> × 0.168 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> × 0.01 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> is proposed that depicts 8.5% impedance bandwidth. Thereafter, the interelement coupling of the antenna system is significantly reduced (>-37 dB) by employing the neutralization line between the two radiating elements and defected ground structure. A system-level performance of the proposed antenna has also been analyzed for a planar implantable device. Moreover, specific absorption rate of the proposed antenna is evaluated that meets (SAR <; 1.6 W/kg) the health safety requirements. A wireless link budget analysis is performed that satisfactorily fulfills the requirements for high-speed biotelemetry application.

Orthogonal mode dual band MIMO antenna system for 5G smartphone applications using characteristic mode analysis

PurposeThe purpose of this paper is to provide a miniaturized antenna design for a mobile phone. The second design is 2 × 4 elements multiple-input multiple-output (MIMO) antenna with 8 port having a substrate size is 20 × 40 mm2 which fits easier within smartphone handset devices for fifth generation technology.Design/methodology/approachIn this work, the first design is a conventional patch antenna, and its dual-band characteristics are obtained by characteristic mode analysis. In this method, orthogonal modes are carried out for 28 GHz and 38 GHz, and further, both orthogonal modes are excited by finite integration technique full-wave method with 50 Ohm single port coaxial feed line.FindingsIn this configuration, better return loss, high gain, larger bandwidths and low envelope correlation coefficient (ECC) are evaluated by the full-wave simulation computer simulation technology (CST) studio suite.Originality/valueIn this arrangement, the performance metrics of the antenna are analyzed using electromagnetic simulator CST Studio suite.

Covert Communication Achieved by a Full-Duplex Multi-Antenna Receiver in Wireless Networks

In this paper, we consider a covert communication system with a multi-antenna full-duplex (FD) receiver to enhance covert performance. More precisely, the receiver Bob (i.e., multiple antennas) selects the best antenna to receive the covert message, and then it sends artificial noise (AN) to the warden Willie causing uncertainty by utilizing an antenna among the remaining antennas. In order to take full advantage of multi-antenna technology, we consider two cases: (1) Willie does not know which antenna Bob chooses to send AN, and Willie knows only part of the channel information. (2) Willie knows which antenna Bob chooses to send AN, and Willie knows all the channel information. Based on the analysis of the optimal detection threshold, we derive the minimum detection error probability of the two cases. Furthermore, given the pre-determined convert constraints, the closed-form expression of the maximum effective convert rate is derived. When the power of AN sent by Bob is greater than that of covert message sent by the sender Alice, surprised research results are shown: (1) the detection error rate of case 1 is higher than that of case 2. (2) the effective covert rate of case 1 is always lower than that of case 2. The simulation results show that the proposed scheme is more conducive to sending covert messages for Alice; in addition, the numerical results imply that the maximum effective covert rate of the system using the multi-antenna FD receiver is significantly higher than that of the traditional dual-antenna FD receiver system.

Integrated Planar LTE MIMO Dual-antenna System on Laptop Computer’s Hinge

ABSTRACT This paper presents an LTE MIMO dual antenna system for laptops. The LTE antenna is composed of a fed strip and a shorted strip. The antenna structure is very simple and can cover LTE octa-band operation (LET700/GSM850/900/GSM1800/1900/UMTS /LTE2300/2500) with the antenna size only 50 × 5 mm2 printed on the FR4 substrate. The LTE antenna is a design concept that integrates the metal hinges and ground plane into one of the antenna’s resonant paths, which can effectively reduce the size of the antenna and can be tightly configured with the surrounding metal, while at the same time the antenna has good radiation characteristics. To effectively utilize the existing space of laptops, two LTE antennas of the same structure and size are symmetrically arranged in the clearance area on the left and right sides of the hinge of the laptop to form a MIMO dual antenna system. The measured isolation in the operating frequency band is better than 24 dB, while the measured antenna efficiency is better than 40%, which exhibits good antenna characteristics.

Dual antenna system for metal frame mobile phone applications

A dual antenna system with 77 mm × 10 mm × 7.5 mm for metal frame (MF) LTE/GPS mobile phones is proposed and studied. The antenna proposed in this study comprises two antenna elements (Ant 1 and Ant 2) and a decoupling line. Ant 1 as the main antenna that covers the lower band (698-960 MHz), the GPS band, and the higher band (1710-2690 MHz) consisting of a ground branch, a coupled line, and a tuning line. Ant 2 as the auxiliary antenna that covers the higher band consisting of a monopole branch and a match circuit. Ant 1 and Ant 2 form a two-element MIMO antenna covering the higher band. The advantages of the proposed antenna are that the main antenna (Ant 1) covers the GPS band and all of the 2G/3G/4G bands, and the two-element MIMO antenna covering the higher band, which consists of Ant 1 and Ant 2 located at the same side of a mobile phone with an MF, is obtained. A prototype is manufactured and tested. For Ant 1, the measured working bands (under −6 dB condition) are 685 to 965 MHz and 1480 to 2800 MHz, and the LTE700, GSM850, GSM900, GPS, GSM1800, GSM1900, UMTS, LTE2300, and LTE2500 bands are covered. For Ant 2, the measured working band (under −6 dB condition) is 1640 to 2720 MHz, and the GSM1800, GSM1900, UMTS, LTE2300, and LTE2500 bands are covered. The measured isolations between Ant 1 and Ant 2 are larger than 12 dB at the working bands. The measured efficiencies, envelope correlation coefficients, and mean effective gains are also presented.

An integrated MIMO filtenna with wide band-narrow band functionality

In this literature an integrated multiple-input-multiple-output (MIMO) filtenna for both Wideband (WB)-Narrowband (NB) functionality is investigated. The approach to the design involves a two element, dual mode MIMO antenna system. In wideband mode two identical circular radiators are used while a pair of rectangular split ring resonator (RSRR) based band pass filters integrated in to the WB antennas are used in narrowband mode. The ground plane is extended in the shape of T shaped stub for the shake of isolation improvement between the ports. All the scattering parameters (S11/S22, S12/S21) of the fabricated antenna prototype are verified in both simulation and measurement for the determination of better antenna performance. Here, a wide impedance bandwidth of 1.2–6 GHz is achieved during wideband mode of operation whereas a frequency response of 3.3–4.0 GHz is found in narrowband mode with isolation in both the cases less than −25 dB and −30 dB respectively. Moreover the performance parameters of MIMO antenna system such as envelope correlation coefficient (ECC), diversity gain (DG) and mean effective gain (MEG) are also evaluated using S matrix to strengthen the design concept.