Wireless WLAN Research Articles

Environmental causality calibration: Advancing WLAN RF fingerprinting for precise indoor localization.

In recent years, considerable and valuable research progress has been made in indoor positioning technologies based on WLAN Radio Frequency (RF) fingerprinting, identifying it as one of the most promising positioning technologies with substantial potential for wider adoption. However, indoor environmental factors significantly influence the propagation of wireless RF signals, resulting in a considerable decrease in positioning accuracy as the indoor environmental conditions vary. Thus, effectively mitigating the impact of indoor environmental factors on WLAN RF fingerprinting-based positioning systems has become a crucial research problem. Currently, there is a dearth of comprehensive research on the influence of indoor climatic factors, particularly the variations in relative humidity, on the propagation of WLAN RF signals within indoor spaces and its consequential impact on positioning accuracy. To address the aforementioned issues, this paper proposes an Adaptive expansion fingerprint database (AeFd) model based on a regression learning algorithm. The AeFd, through the design of a relationship model describing the interaction between fingerprint databases under varying relative humidity, allows the fingerprint database expanded by AeFd to dynamically adapt to the changes in indoor relative humidity. Our experiments show that using the AeFd model with the KNN algorithm, a 5% performance improvement was observed over 10 days and an 8% improvement over 10 months. According to experimental test results, the fingerprint database expansion model AeFd proposed in this paper can effectively expand the fingerprint database under different relative humidity levels, thereby significantly enhancing the positioning performance of the system and improving its stability.

Metamaterial-based Octagonal Ring Penta-band Antenna for Sub-6 GHz 5G, WLAN, and WiMAX Wireless Applications

Metamaterial-based Octagonal Ring Penta-band Antenna for Sub-6 GHz 5G, WLAN, and WiMAX Wireless Applications

Design and performance analysis of 8‐port multi‐service quad‐band MIMO antenna for automotive communication

AbstractIn this paper, a low profile compact 8‐port multiband antenna with polarization diversity principle for automotive communication is proposed. The geometric of the proposed MIMO antenna is integrated with multiple stubs on substrate having a size of 0.94λg × 0.94λg. The proposed design resonates at multiple frequencies of 1.8, 2.4, 5.2, and 5.8 GHz, respectively for GSM, ISM bands and WLAN wireless services which covers the bandwidth of 2.8%, 5%, 5%, and 5.6%, respectively with S11 ≤ −10 dB. Besides, the measured results provide a peak gain of 4.3, 3.1, 4.5, and 4.2 dBi at 1.8, 2.4, 5.2, and 5.8 GHz, omni directional radiation pattern with more than 80% of efficiency in all operating bands. The MIMO structure provides a good isolation of greater than 20 dB without decoupling structure, envelope correlation coefficient of ≤0.1, diversity gain of ≥9.99 dB, mean effective gain of <1 dB, total active reflection coefficient ≤−10 dB, channel capacity loss of ≤0.25 bits/s/Hz. Finally, the housing effect of MIMO antenna is analyzed in the vehicular environment which provides good performance for Vehicular to Intravehicular communication.

A Wide-Band Antenna with Circular Polarization Utilizing a U-Shaped Radiator and Parasitic Strip for Wireless Communications.

A circularly polarized (CP) and wide-band monopole antenna with a miniaturized size is suggested in this study. The suggested structure is composed of a U-shaped radiator on the front side, a partial ground plane with two rectangle slots, and a quadrilateral-shaped parasitic strip on the back side of the FR4 substrate. A wide-band operation with S11 ≤ -10 dB was achieved by regulating the radiator and the partial ground that was placed on the second side of the antenna substrate. The CP was achieved when excited two modes with the same amplitude and a 90° phase difference. This could be generated by regulating the slots' dimensions in the ground plane. Moreover, a quadrilateral-shaped parasitic strip placed on the second side with the partial ground was utilized to extend the 3 dB axial ratio (AR) bandwidth. The suggested structure is simulated, prototyped, and measured to confirm the desired requirements with a total size of 30 × 32 mm2 (0.4 × 0.42 λ0 at 4 GHz). The tested outcomes have a bandwidth of S11 ≤ -10 dB (81.25%) (5.2 GHz, 3.8-9 GHz) and a 3 dB axial ratio (AR) bandwidth (30.7%) (1.63 GHz, 4.48-6.11 GHz). The antenna's different parameters are discussed, which recommend the suggested antenna to be used in UWB, sub 6 GHz, and WLAN wireless applications.

Miniaturized reconfigurable dielectric resonator antenna array with reduced beam squinting

In this study, a compact reconfigurable dielectric resonator antenna (DRA) array is proposed to operate in the band IEEE 802.11 WLAN. The main goal of this design is to propose an array feeding topology to avoid radiated beam squinting due to frequency alteration and acquire some gain enhancement with miniaturized array size. For that, the parallel–series geometry is used to layout a microstrip feeder with four output ports on the front plane. Each output port coupled with a rectangular slot (RS) at the bottom plane, and a rectangular dielectric resonator (RDR) mounted above the RS. The frequency reconfigurability is attained by employing PIN diodes that are integrated with the four output ports to operate as switches. Moreover, an impedance equivalent circuit model of the proposed array is postulated for studying the resonance behavior to ensure the validity of the proposed design prior to simulation and fabrication. The prototype 64 × 18 mm2 achieves frequency agility in the range of 5.8 to 5.17 GHz. Also, the realized gain ranges from 12.2 to 10. 5 dBi. The array specifications make it a decent potential candidate to be used for WLAN wireless systems.

Compact Quad Band MIMO Antenna Design with Enhanced Gain for Wireless Communications.

In this paper, a novel microstrip line-fed meander-line-based four-elements quad band Multiple Input and Multiple Output (MIMO) antenna is proposed with a gain enhancement technique. The proposed structure resonates at four bands simultaneously, that is, 1.23, 2.45, 3.5 and 4.9 GHz, which resemble GPS L2, Wi-Fi, Wi-MAX and WLAN wireless application bands, respectively. The unit element is extended to four elements MIMO antenna structure exhibiting isolation of more than 22 dB between the adjacent elements without disturbing the resonant frequencies. In order to enhance the gain, two orthogonal microstrip lines are incorporated between the antenna elements which result in significant gain improvement over all the four resonances. Furthermore, the diversity performance of the MIMO structure is analyzed. The Envelope Co-Relation Coefficient (ECC), Diversity Gain (DG), Channel Capacity Loss (CCL), Mean Effective Gain (MEG) and Multiplexing Efficiency are obtained as 0.003, 10 dB, 0.0025 bps/Hz, −3 dB (almost) and 0.64 (min.), respectively, which are competent and compatible with practical wireless applications. The Total Active Reflection Coefficient (TARC) resembles the characteristic of the individual antenna elements. The layout area of the overall MIMO antenna is 0.33 λ × 0.29 λ, where λ is the free-space wavelength corresponding to the lowest resonance. The advantage of the proposed structure has been assessed by comparing it with previously reported MIMO structures based on number of antenna elements, isolation, gain, CCL and compactness. A prototype of the proposed MIMO structure is fabricated, and the measured results are found to be aligned with the simulated results.

A Miniaturized Planar Monopole Antenna Based on a Coupling Structure for Compact Mobile Internet of Things (IoT) and Electric Vehicles (EVs) Device Applications in 5G, LTE, WLAN, WiMAX, Sirius/XM Radio, V2X, and DSRC Wireless Systems

A miniaturized internal antenna with monopole structure is constituted, including three radiating strips of a compact prototype and a back-coupling pad to improve the impedance matching, which achieves a wide bandwidth of 2.972 GHz between the operating frequencies of 2315–5285 MHz, and is introduced and researched. There is an urgent need for a complete frequency-continuous and large bandwidth design in the current wireless communication design to achieve a multimode, multifrequency, physical phenomenon design with large bandwidth and continuous operating frequency. The recommended antenna provides a broadband operation in an electric vehicles (EVs) and Internet of Things (IoT) devices application embedded in the wireless communication standard for 5G, LTE, V2X, WLAN, WiMAX, Sirius/XM Radio, V2X, and DSRC to support the multiband application. This design is embedded side edge of overall placement in the device and is integrated applicable to the trend of heterogeneous wireless multiple access networks in electric vehicle and Internet of Things system devices, which covered the 5G with supporting the band of n7/n38/n40/n53/n77/n78/n79/n90, the 4G with supporting the band of 7/38/40/41/42/43/48/67, the V2X and DSRC for the operating frequencies between 2500 and 5000 MHz, the Sirius/XM Radio for the operating frequencies of 2320–2345 MHz, the ISM band of WiFi and BT covering the band of 2450–2483.5 and 5150–5350 MHz, and the WiMAX also supporting the band of 2300–2690 and 3400–3690 MHz. Moreover, the compact antenna manufactured an FR4 material with the antenna area of 5 × 10 × 0.8 mm3 and the ground area of 33.5 × 10 × 0.8 mm3. The proposed design better benefits a narrow space on the PCB with a low profile and is easy to make with a circuit board design.

Quintuple band circular monopole antenna with innovative 3-D printed PLA substrate for wireless applications

Abstract In this paper, a circular antenna with a 3-D printed substrate is introduced to achieve a multiband behavior. The circular antenna is matched using a key-shaped stub located on the perimeter of the designed antenna. The 3-DP circular antenna adopted the apollonian gasket technique to perform the multi-circular cuttings in the Polylactic Acid (PLA) substrate as an innovative technique to obtain quintuple bands. The proposed antenna is designed to operate for Bluetooth, WLAN, WiMAX, and other wireless applications in S-band and C-band. The designed antenna has a compact size of 61.1 × 43.6 × 1 mm3. The prototype of the suggested 3-D printed antenna is fabricated and measured to confirm the simulation results. A good agreement is evident between simulation and experimental results which validates the design concept.

Modified Koch Fractal Antenna for Multi and Wideband Wireless Applications

This paper focuses on the design and development of modified Koch fractal antenna. Compared to traditional Koch curve antenna, the presented antenna possesses a greater number of frequency bands and better impedance matching. Furthermore, the bacterial foraging optimization (BFO) approach is implemented to enhance the impedance bandwidth. The developed technique has been verified by employing various numerical simulations. The design parameters generated from the optimization procedure have been utilized to manufacture the antenna and the respective experimental and simulated results compared. The measured results show that the designed antenna exhibits multi and wideband behavior, covering WLAN, WIMAX, and various other wireless applications.

Simple ultra-wide band antenna with double band rejection capability using double inclined elliptical split ring resonators

In this paper, CPW-Fed ultra wideband (UWB) planar monopole antenna loaded by double inclined elliptical split ring resonators (ESRRs) for double band-notch characteristics is introduced, examined, and fabricated. Two different ESRRs with different dimensions are printed in the antenna backside to notch two different frequencies in the UWB frequency range instead of using two ESRR pairs as usual. The ESRRs are then rotated and the corresponding return loss is studied. Different notch frequencies can be obtained by varying the ESRRs’ dimensions. Finite element method FEM and finite integration technique FIT are used to simulate the proposed structures through the usage of Ansys HFSS and CST MWS. Good agreement between both results has been obtained. Two different prototypes of the proposed antenna are fabricated and their reflection characteristics are measured. The first antenna is the UWB antenna with two straight ESRRs in which two notch frequencies at 5.3 GHz and 6.8 GHz have been obtained. The second antenna is the UWB antenna with two inclined ESRRs in which two notch frequencies at 5.1 GHz and 6.9 GHz have been obtained. In both cases, good agreement between simulated and measured results has been obtained and the discrepancies are due to fabrication and alignment errors. Also in both cases the proposed antennas notch WLAN and C-band wireless coexisted applications. A directive radiation pattern in E-plane and omnidirectional radiation patterns in the H-plane could be observed. Also the gain is suppressed in the notch frequencies in both cases. The group delay is nearly stable in the UWB frequency range, except at the notch frequencies, which is distorted sharply. So, the proposed antenna is a good candidate for the modern UWB systems.

A coplanar waveguide‐fed broadband circularly polarized microstrip antenna for conformal applications

A broadband circularly polarized conformal microstrip antenna based on coplanar waveguide feeding is presented. By embedding a pair of disturbing branches on a rectangular grounded metal ring and protruding into the ring a pentagonal monopole, the measured bandwidths of 3-dB axial ratio and 10-dB impedance achieve 58.5% (4.6 to 8.4 GHz) and 67.7% (4.3 to 8.7GHz), respectively. The antenna has a small form factor, a low profile and low manufacturing costs. Simulated and measured results indicate that this antenna has excellent adaptability to cylindrical carriers with different radius, which is adapted for potential conformal applications. In addition, the proposed antenna can find applications in WLAN (5, 5.2, and 5.8 GHz), WiMAX (5.5GHz), and other C-band (4GHz-8GHz) wireless communications.

A Dual Band AMC Backed Antenna for WLAN, WiMAX and 5G Wireless Applications

This paper presents a multiband low profile antenna aimed for its application in existing WLAN, WiMAX and sub-6 GHz fifth generation (5G) frequency bands. The design incorporates a simple planar monopole antenna with slots etched on it to be able to operate in two frequency bands with (S11< -10 dB) ranging from 2.38 - 2.7 GHz and 3.28 - 5.8 GHz with percentage impedance bandwidths of 16 and 56. The peak gains of the antenna within the bands were observed to be 2.1 and 4.3 dBi respectively. In order to further enhance the Gain and improve the radiation characteristics of the antenna, a dual band artificial magnetic conductor (AMC) surface is designed and employed as a reflector at the ground side of the main radiator. The antenna and AMC 4x4 array prototypes are fabricated and its performance is measured. It is observed that there is an enhancement in the gain of 5 dB in the first band and 2.8 dB in the second band of operation.

Hexagonal shaped fractal MIMO antenna for multiband wireless applications

A hexagonal shaped fractal Multiple input Multiple Output (MIMO) antenna resonates to six different frequencies is presented. A dumbbell structure with hexagon shaped defected ground structure (DGS) is created in the ground plane. Two antenna elements sharing a common ground plane are positioned orthogonal to each other for better isolation. The antenna is designed, fabricated using FR4 substrate with 1.6 mm thickness and tested experimentally. The antenna provides high peak gain of 8.69 dBi at 8.33 GHz. The multiband MIMO antenna resonates for the frequencies 1.9 GHz, 2.9 GHz, 3.2 GHz, 5.0 GHz, 5.6 GHz and 7.74 GHz. Mutual coupling is better than − 20 dB and the peak gain of the antenna ranges from 3.2 to 8.69 dBi. The designed orthogonal two element MIMO antenna is suitable for GSM, PCS, WLAN and Wi-MAX wireless applications. Simulation work is carried out by ADS tool and fabricated antenna is tested with vector network analyser.

Wireless network signal monitoring based on LAN packet capture and protocol analysis on grid programming

As a kind of network technology with super wide coverage and obvious transmission rate advantage, wireless network has become the most widely used network technology in people’s daily life. However, when information is transmitted and exchanged in wireless networks, information blocking often occurs, which restrains the transmission rate. Therefore, the signal monitoring technology in wireless network is of great practical significance. This paper will focus on the breakthrough of wireless WLAN packet capture and protocol analysis technology in computer communication technology, and use the grid programming method to analyze the implementation process of the whole system function module. Based on this technology, a wireless network detection system is developed in VC + + 7 environment, and the algorithm flow chart is given. Finally, the system designed in this paper will be tested on Linux platform. The experimental results show that the wireless network signal monitoring technology proposed in this paper can monitor the operation of wireless network in real time. The corresponding detection accuracy error is controlled at about 1%, and the corresponding detection accuracy can reach about 60% in different signal background.

Design and development of triple-band compact ACS-fed MIMO antenna for 2.4/3.5/5 GHz WLAN/WiMAX applications

In this paper, a very small size (20 × 14.75 mm2) triple-band multiple-input multiple-output (MIMO) microstrip patch antenna for WLAN (2.4/5.2/5.8 GHz) and WiMAX (2.5/3.5/5.5 GHz) wireless applications. The goal of this paper is to merge these two wireless standards into a single antenna that can be easily accommodated inside the devices operating in three different frequency ranges. The proposed MIMO antenna consists of an asymmetric coplanar strip (ACS) feedline loaded with an inverted L-shaped slot and a meanderline. The inverted L-shaped slot and the meanderline both having an electrical length 0.5λ, are responsible for the achieving the operating band around 3.5 and 2.4 GHz, respectively whereas the ACS feedline is responsible for the generation of 5 GHz frequency band. The fabricated prototype of the proposed MIMO antenna when tested, shows three distinct frequency bands; I from 2.38 to 3.00 GHz, II from 3.21 to 3.61 GHz and III from 5.02 to 6.18 GHz that covers entire frequency bands of WLAN and WiMAX wireless applications along with different standards of IEEE 802.11 including a/b/j/p/g/n/ac/ax. The peak gain in I, II and III frequency bands is 7.93, 4.23 and 7.57 dBi, respectively. In addition, the diversity performance in terms of envelope correlation coefficient, diversity gain, multiplexing efficiency, total active reflection coefficient, and mean effective gain is also performed for the proposed MIMO antenna.

Asymmetric circularly polarized open‐slot antenna

A circularly polarized printed antenna using an asymmetric open-slot is designed in this paper. The presented antenna consists of conducting ground plane with open wide-slot, fed electromagnetically by a microstrip feedline. The slot and feedline are positioned at the edge of the ground plane and substrate, hence making the antenna asymmetric. The measured results show that the |S11| < −10 dB impedance bandwidth is 125% (3.2-14 GHz) and the broadband axial ratio bandwidth is 61% (3.2-6 GHz). The antenna is very simple and has a small size of 25 mm × 25 mm, making it attractive for compact wireless WLAN, ISM, WiMAX, and C-band applications.

A Novel Dual-Band Binary Branch Fractal Bionic Antenna for Mobile Terminals

A novel two-iteration binary tree fractal bionic structure antenna is proposed for the third generation (3G), fourth generation (4G), WLAN, and Bluetooth wireless applications in the paper, which is based on the principles of conventional microstrip monopole antenna and resonant coupling technique, combined with the advantages of fractal geometry. A new fractal structure was presented for antenna radiator, similar to the tree in nature. The proposed antenna adapted two iterations on a fractal structure radiator, which covers mobile applications in two broad frequency bands with a bandwidth of 44.2% (1.85–2.9 GHz) for TD-SCDMA, WCDMA, CDMA2000, LTE33-41, and Bluetooth frequency bands, and 11.5% (4.9–5.5 GHz) for WLAN frequency band. The proposed antenna was fabricated on a G10/FR4 substrate with a dielectric constant of 4.4 and a size of 50 × 40 mm2. The good agreement between the measurement results and the simulation results validate that the proposed design approach meet the requirements for various wireless applications.

Isolation Frequency Switchable MIMO Antenna for PCS, WIMAX and WLAN Application

In this study, a lumped component based frequency reconfigurable multiple-input-multiple-output (MIMO) receiving wire design is presented. The proposed antenna is composed of a planar structure in form of F-shaped together with a slotted and defected ground structure for bandwidth and isolation enhancement. The MIMO antenna operates in six frequencies upon the state of the four lumped element switches. The proposed receiving wire design exhibits a multiband frequency reconfigurable characteristics from 1-7GHz with isolation of more than 14dB for the whole band, with efficiency of about 75%. The MIMO antenna’s behavior in terms of ratio of square root of the sum of power reflected wave to the incident wave (TARC), ECC and CCL are all within the acceptable limits. The design is suitable for personal communication system (PCS), WIMAX and WLAN wireless applications.

Design of Multiband E-Shaped Patch Antenna with Hexagonal Slot for WLAN Applications

Abstract The objective of E-shaped patch antenna with hexagonal slot is to operate in the ISM band for different kind of applications, such as WLAN, GPS, and various modern wireless systems. The posit antenna is designed using FR4 substrate having a dielectric constant of 4.4 with a thickness of 1.6 mm. Probe feed technique is used for this antenna design. A parametric study was included to determine the effect of design approaches and the antenna performance. The realization of the designed antenna was analyzed in term of boost (gain), return loss, and radiation pattern. The design was upsurged to confirm the best achievable result. This antenna resonates at three different frequencies at 1.6 GHz, 3.24 GHz, and 5.6 GHz with a reflection coefficient less than -10 dB and VSWR&lt;2.

A Circular Coplanar Waveguide Fed Microstrip Patch Antenna with Modified Triangular Ground for UWB Applications

This research article gives a detailed insight of the design, simulation of a compact circular shaped microstrip patch antenna that is fed using a coplanar waveguide feed (CPW for practical wireless communication applications). The antenna is typically designed for Ultra wideband (1.46-6GHz), Bluetooth (2.4GHz), ZIGBEE (2.4GHz), WLAN (5.15- 5.35 GHz and 5.725- 5.825), Wi-Fi (2.4-2.485GHz) and HIPERLAN-2(5.15 - 5.35 GHz and 5.470 -5.725GHz) wireless applications with stop band characteristics for the H (partial C band). The proposed antenna has an overall packaged structure dimensions of 78 x75 x1.605 mm3 and is fabricated on FR4 substrate as a circular patch antenna with a coplanar ground .The commercially available laminate FR4 substrate that is used has a dielectric constant of 4.4, height of 1.6mm and a loss tangent of 0.0024.The prospective antenna shows a simulated impedance bandwidth of 4.54 GHz. The coplanar waveguide feeding used with this antenna helps in improving antenna performance in terms of its impedance bandwidth as this geometry helps in creating multiple current loops at the antenna structure, thereby exciting nearby frequencies that merge to show a broadband of operation. The antenna’s operational bandwidth is also improved by the concept of modified ground, in which triangular and rectangular shapes are added symmetrically on both sides of ground plane that provide a better fringing effect and hence an improved bandwidth.