Wireless Local Area Network Applications Research Articles

A Low Profile Dual-Band High Gain Directional Antenna for Anti-Interference WLAN Station Applications

This paper presents a low-profile dual-band antenna with directional radiation characteristics for wireless local area network (WLAN) applications. The proposed directional antenna is composed of a coupling microstrip line, two F-shaped strips, two rectangular strips, and a defected ground plane. The measured impedance bandwidth of the proposed antenna is 180 MHz (2.33–2.51 GHz) and 830 MHz (5.09–5.92 GHz), which can cover Institute of Electrical and Electronic Engineers (IEEE) 802.11 a/b/g frequency bands. The dual-band antenna exhibits a desirable directional radiation patterns in the vertical and horizontal planes with the peak gain of 6.55 dBi in the lower frequency band and 8.1 dBi in the higher frequency band. The measured antenna efficiency is 70% at 2.4 GHz and 84.5% at 5.5 GHz. The proposed dual-band WLAN station antenna is designed on a FR4 substrate with overall dimensions of 69 mm × 50 mm × 1.6 mm.

A novel QoE based cross-layer scheduling scheme for video applications in 802.11 wireless LANs

In the past two decades, 802.11 based Wireless Local Area Networks (WLANs) have gained popularity in offering Internet services and increasingly supporting data driven video streaming applications. Such services demand enhanced view quality to all the end-users in the network. However, due to the sharing of limited resources and lack of proper scheduling mechanisms, WLANs are unable to meet the requirements of numerous video users and provide them better quality. Therefore, an effective resource scheduling approach is needed that can achieve high user satisfaction for the ever changing user needs for quality video viewing. In this paper, a Quality of Experience based Cross-Layer Scheduling (QoECLS) scheme to enhance the user experience for video applications in WLANs is proposed. Here, the Mean Opinion Score has been used as a measure to evaluate the user experience. In order to provide the average user throughput with guarantee of fairness among users, the QoECLS scheme uses cross-layer information from the application and physical layer, respectively. The QoECLS algorithm allocates transmission resources by considering application feedback along with channel state information and buffer status. The performance of the QoECLS approach was extensively studied through simulations and the results showed an improvement in user experience and throughput, while maintaining fairness among the users. In terms of throughput, the proposed scheme achieves 25%, 45 %, and 50% improvement compared to QoE Aware Scheduling scheme, Modified-Largest Weighted Delay First scheduler and Exponential-Proportional Fair scheduler, respectively.

Compact omnidirectional dual‐band dipole antenna with reduced ground plane effect

AbstractIn this letter, a compact omnidirectional dual‐band antenna is designed for wireless local area network applications. The proposed antenna is printed on the two sides of an FR4 substrate that the total dimension is 12 × 46 × 0.5 mm3. A dipole antenna is used to cover the lower operating band (2.45 GHz), while a capacitances‐loaded patch generates a higher resonance (5.5 GHz). This antenna has a good impedance matching in the operation band, and the gain is 2.28 and 4.42 dBi in the lower and upper bands, respectively. To address the problem that the performance will drastically decline when the antenna is located on a ground, a quarter wavelength spiral line is employed to decrease the negative effect of the ground. Two proposed dipole antennas, placed on a horizontal ground as a MIMO antenna system, are analyzed with different configurations. The results reveal that the proposed method can effectively reduce the ground plane effect and improve the diversity performance, which has huge potential applications in MIMO system.

A Single-Layer Low-Profile Circularly Polarized Filtering Patch Antenna

A single-layer low-profile circularly polarized (CP) filtering patch antenna is investigated for wireless local area network (WLAN) applications. The CP antenna mainly consists of a feeding loop, four L-shaped radiating patches, and a square ground plane. To integrate the filtering function, four thin microstrip stubs and four shorting pins are introduced to the patches, and two U-shaped slots are etched in the feeding loop. These parasitic elements can realize the bandpass filtering function without requiring an external filter. In addition, these elements are skillfully added into the CP antenna, without increasing either the antenna footprint or profile. To verify the design, a prototype operating at 2.4 GHz WLAN band is fabricated and tested. The measured results show that the prototype has a low profile of 0.02λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> , a passband bandwidth (|S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> | <; -10 dB and axial ratio (AR) <; 3 dB) of 4.1%, and a peak gain of 8.3 dBic. Moreover, the prototype also shows a sharp roll-off rate near the passband edge and a good out-of-band suppression level of more than 20 dB in the stopbands.

Concurrent Dual-Band Inverter-Based Low Noise Amplifier (LNA) for WLAN Applications

low noise amplifier (LNA); concurrent; dual-band; inverter-basedIn this paper, a two-stage concurrent dual-band low noise amplifier (DB-LNA) operating at 2.4/5.2-GHz is presented for Wireless Local Area Network (WLAN) applications. The current-reused structure using resistive shunt-shunt feedback is employed to reduce power dissipation and achieve a wide frequency band from DC to-5.5-GHz in the inverter-based LNA. The second inverter-based stage is employed to increase the gain and obtain a flat gain over the frequency band. An LC network is also inserted at the proposed circuit output to shape the dual-band frequency response. The proposed concurrent DB-LNA is designed by RF-TSMC 0.18-µm CMOS technology, which consumes 10.8 mW from a power supply of 1.5 V. The simulation results show that the proposed DB-LNA achieves a direct power gain (S 21 ) of 13.7/14.1 dB, a noise figure (NF) of 4.2/4.6 dB, and an input return loss (S 11 ) of −12.9/−14.6 dBm at the 2.4/5.2-GHz bands.

X-band CMOS VCO for 5 GHz Wireless LAN

The implementation of a low phase noise voltage controlled oscillator (VCO) is important for the signal integrity of wireless communication terminal. A low phase noise wideband VCO for a wireless local area network (WLAN) application is presented in this paper. A 6-bit coarse tune capacitor bank (capbank) and a fine tune varactor are used in the VCO to cover the target band. The simulated oscillation frequency tuning range is from 8.6 to 11.6 GHz. The proposed VCO is desgned using 65 nm CMOS technology with a high quality (Q) factor bondwire inductor. The VCO is biased with 1.8 V VDD and shows 9.7 mA current consumption. The VCO exhibits a phase noise of –122.77 and -111.14 dBc/Hz at 1 MHz offset from 8.6 and 11.6 GHz carrier frequency, respectively. The calculated figure of merit(FOM) is -189 dBC/Hz at 1 MHz offset from 8.6 GHz carrier. The simulated results show that the proposed VCO performance satisfies the required specification of WLAN standard.

Design and analysis of 4 × 4 MIMO antenna with DGS for WLAN applications

AbstractIn this paper, a low profile 4 × 4 multiple input and multiple output (MIMO) antenna is proposed and designed for wireless local area network (WLAN) application using a square split-ring resonator. Initially, a single square-patch antenna is designed with square-shaped split-ring slot. Subsequently, the two-element MIMO antenna is designed and it is extended to four-element MIMO antenna. Finally, the defected ground structure (DGS) is implemented in order to enhance antenna performance. The antenna elements are placed opposite to each other. The mutual coupling between the antennas elements is reduced by DGS. The proposed single, two and four-element antennas operate at 5.8 GHz for WLAN. The overall performance is measured in terms of S parameter, radiation pattern, and envelope correlation coefficient. The simulated results are verified through measurements. The simulated and measured results demonstrate that the proposed 4 × 4 MIMO antenna is the most suitable for WLAN applications.

Dual-Band Flexible Antenna for WLAN/WiMAX Applications

Aim: This paper presents the development of Co-Planar Waveguide (CPW) fed dualband, compact, and flexible antenna. The antenna is designed on flexible substrate jeans; so, it is suitable for wearable applications. Objective: The proposed antenna generates dual-band at 3.36GHz –3.61GHz and at 5.01 GHz – 5.18 GHz. The antenna has a compact size of 40×30 mm2. The antenna consists of a rectangular patch having a slot which is responsible for the first band and slot in the ground plane which is responsible for the second band. Methods: By optimizing the dimensions, the antenna gives dual-band at 3.5 GHz and 5.1 GHz with impedance bandwidth of 250 MHz and 170 MHz, respectively. The performance of the antenna such as gain and radiation pattern over the operating band has been also discussed. Conclusion: This proposed antenna with the first band at 3.5GHz is suitable for Wi-MAX (Worldwide Interoperability for Microwave Access) and second band at 5.1GHz is suitable for Higher Wireless Local Area Network applications (WLAN).

Design and Analysis of Integrated Wilkinson Power Divider-Fed Conformal High-Gain UWB Array Antenna with Band Rejection Characteristics for WLAN Applications

Flexible ultra-wideband (UWB) antenna arrays with band notching characteristics are proposed in this work. A new wideband and high-isolation Wilkinson power divider (WPD) is designed to construct the feed systems of the UWB antenna arrays. The proposed WPD is achieved by introducing a significant modification to the conventional WPD and the new one is composed of four isolation stages. Multiple stages helped to achieve wideband from 2[Formula: see text]GHz to more than 12[Formula: see text]GHz with high isolation characteristics of more than 20[Formula: see text]dB and insertion losses around 3.3[Formula: see text]dB. The designed WPD is then applied to feed two UWB monopole antenna arrays which offer a notched band centered at 5.5[Formula: see text]GHz to reject interference from wireless local area network (WLAN) system and can be integrated with curved surfaces. To verify the performance of the proposed structure, two array configurations are practically fabricated and measured. The results show that both the arrays have UWB operational bandwidth (3.5–11.8[Formula: see text]GHz for [Formula: see text] array and 3.6–12[Formula: see text]GHz for [Formula: see text] array) that includes the UWB spectrum. Attractive agreement between simulation and measurement results is obtained. Furthermore, the bending test is carried out on the [Formula: see text] array showing the good performance of the proposed system when installed on curved surfaces for different bent angles.

Performance enhancement of circularly polarized patch antenna using slotted circular EBG-based metasurface

Abstract A 3 × 3 slotted circular Electromagnetic Band gap based Metasurface (SCEBG-MS) has been presented in this article, which enhances the performance of a circularly polarized (CP) patch antenna by improving its impedance bandwidth, axial ratio bandwidth and gain. The proposed antenna is having a low profile of 0.065 λ o (λ o is the free-space wavelength at center frequency of 6.16 GHz) with ground size selection of 30 × 30 mm. The prototype antenna achieves a measured −10 dB impedance bandwidth of 37% (5.02–7.30 GHz) and measured 3-dB axial ratio bandwidth of 5.9% (5.24–5.56 GHz). Furthermore, the antenna yields a good peak gain of 6.6 dBic in the CP bandwidth which makes it a promising candidate for Wireless Local Area Network (WLAN) applications. Experimental results obtained from the fabricated prototype closely matched with the simulated results.

A multi-slotted antenna for LTE/5G Sub-6 GHz wireless communication applications

AbstractThis paper presents a low-profile multi-slotted patch antenna for long term evolution (LTE) and fifth-generation (5G) communication applications. The studied antenna comprised of a stepped patch and a ground plane. To attain the required operating band, three slots have been inserted within the patch. The insertion of the slots enhances the capacitive effect and helps the prototype antenna to achieve an operating band ranging from 3.15 to 5.55 GHz (S11 ≤−10 dB), covering the N77/N78/N79 for sub-6 GHz 5G wireless communications and LTE bands of 22/42/43/46. The wideband antenna presented in this paper offers omnidirectional stable radiation patterns, good gains, and efficiency with a compact size which make this design an ideal contender for wireless fidelity (WiFi), wireless local area network (WLAN), LTE, and sub-6 GHz 5G communication applications.

A miniaturized high gain dipole array antenna for 2.4/5 GHz wireless local area network applications

AbstractA miniaturized high gain dipole array antenna for 2.4/5 GHz wireless local area network (WLAN) applications (2.4‐2.5/5.15‐5.85 GHz) is proposed in this paper. The proposed antenna is composed of a 1 × 3 dipole array, a U‐shaped branch, and a double‐layer feedline. Dual‐band operation is realized by using a double‐branch dipole. The peak gain of the proposed dipole array antenna is improved due to the in‐phase current distributions on dipole elements. A U‐shaped branch is added to further enhance the peak gain in the lower band. For miniaturization, the half‐cutting method is applied. One prototype of the proposed miniaturized antenna with a size of 168 × 10.5 × 0.6 mm3 is manufactured and measured. As a result, the proposed antenna provides the operating bands of 2.30 to 2.59 GHz and 5.10 to 6.73 GHz (voltage standing wave ratio ≤ 2), fully covering 2.4/5 GHz WLAN band. Over the lower/higher band, the peak gain and efficiency are higher than 4.2/5 dBi and 58%/49%, respectively. Furthermore, good omnidirectional radiation characteristic in the horizontal plane is achieved.

Mutual Coupling Reduction in Microstrip Antennas using Defected Ground Structure

A Multiple Input Multiple Output (MIMO) antenna with high isolation is proposed in this paper. The proposed antenna includes two sets of four elements (2 x 2) and it is yielded at the central frequency of 5.5 GHz for Wireless Local Area Network (WLAN) applications. Based on RT5880 with height of 1.575 mm, the overall size of MIMO antenna is 140 x 76 x 1.575 mm3. To get high isolation between antenna elements, a Defected Ground Structure (DGS) is integrated on ground plane. Besides, the MIMO antenna witnesses a large bandwidth of 9.1% and an efficiency of 90% while the pick gain is 8.5 dBi. The measurement results are compared to simulation ones to verify the performance of the proposed antenna.

Split labeling diversity for wireless half-duplex relay assisted cooperative communication systems

Labeling diversity (LD) is a well-known technique proposed for multi-antenna Wireless local area network (WLAN) applications . In this paper, we propose LD for three-terminal cooperative communication schemes i.e., Decode and Forward (DF) and Coded-cooperative (CC) schemes with each terminal using a single antenna for transmission. The Boosted space-time codeword is jointly constructed by source and a relay node in two phases and joint iterative detection and decoding are used at the destination node. This technique shows that the gains from LD can be further enhanced when used in cooperative communication schemes. Numerical analysis reveal that the proposed schemes DF and CC provide full diversity gains, over non-cooperative schemes, later scheme being the most successful one, under identical conditions using less number of antennas at each communication node and with reduced receiver complexity.

A miniaturized electromagnetically coupled patch antenna design using eroded ground plane

AbstractA novel electromagnetically coupled circular patch antenna (CPA) with an eroded ground plane is proposed for the wireless local area network (WLAN) application. First, a simple CPA is designed for 2.4‐GHz WLAN band. At this frequency, the physical size of the CPA is large. Therefore, a CPA is designed at a higher frequency with much lesser dimensions, and some portion of the ground plane is eroded to observe the percentage of resonant frequency reduction. In order to avail the WLAN services at 2.4 GHz, a CPA is optimally designed at 5.76 GHz based on the same proportionality technique with an eroded ground plane. This miniaturized antenna resonates at 2.4 GHz frequency with excellent reflection and radiation characteristics. The simulation software ANSYS high‐frequency structure simulator is considered for the design of the proposed CPA. The CPA is physically fabricated and its characteristics are validated with the simulation result. It is also compared with some of the antennas available in the literature for the WLAN application. The comparative study shows that the proposed CPA is a miniaturized one with attractive performance parameters.

High-gain low-profile rectangular microstrip patch antenna with Yagi elements

ABSTRACT This paper presents a novel high gain rectangular microstrip patch antenna (RMSA) with vertically placed Yagi elements. The antenna is fed by a coaxial probe to excite TM01 fundamental waves at 2.4GHz, which is suitable for wireless local area network (WLAN) applications. In order to increase the antenna gain, Yagi elements are placed in groups of 5, on each side of the substrate in order to serveas directors for the radiating slots as well as the ground reflections. The proposed antenna offers 1.3dB gain improvement and %3 .1 impedance bandwidth increase in comparison to the plain rectangular microstrip antenna with the same specifications. The advantage of this antenna is to provide an easy and cost effective solution to increase microstrip antenna gain, particularly in 8-10dB range, without disruptingits planar structure.

Compact dual‐band near/far‐field dipole antenna/tag

This study presents a compact printed dipole antenna/tag loaded by metamaterial (MTM) inclusions for portable near/far-field communication/identification applications. It is shown that loading a printed dipole antenna by epsilon negative inclusions can lead to achieving the miniaturised, dual-band, low-profile antenna. To realise this concept, inductively loaded wire (ILW) has been proposed. To implement inductive loads a meander-line structure is designed and manufactured. Simulation results show that placing the MTM cell in the vicinity of a dipole antenna causes to having an additional resonant frequency which is lower than the natural resonant frequency of a simple unloaded dipole antenna. With the aid of ILW-MTM, a low-frequency band at 2400 MHz for the wireless local area network (WLAN) and near-field radio frequency identification applications is achieved. The higher frequency band is expanded for 5800 MHz services (4900–6500 MHz) WLAN and worldwide interoperability for microwave access band. The antenna prototype is fabricated and measured. Good agreement has been observed between the simulation and measurement results.

Low-profile 2.4/5.8 GHz MIMO/diversity antenna for WLAN applications

ABSTRACT A low-profile multi-input-multi-output (MIMO)/diversity antenna suitable for wireless local area network (WLAN) applications is presented. In the proposed antenna, two identical elements (each of size 20 × 47 mm2) are designed to operate at 2.4 GHz and other two identical elements (each of size 20.5 × 20 mm2) at 5.8 GHz. All elements of the proposed diversity antenna are printed on 1.6 mm thick FR-4 substrate in a coplanar configuration. By optimizing the distance between the antenna elements (in horizontal and vertical directions), optimal isolation and diversity performance are achieved. Compared to a single feed dual-band antenna, the MIMO/diversity antenna has the ability to transmit or receive the 2.4 and 5.8 GHz signals simultaneously, without any external switching circuit between the module and the proposed antenna.

Printed array antenna with an elephant trunk shape radiating patch for Bluetooth and WLAN applications

PurposeThis purpose of this study is to present a novel four-element array antenna in combination with a modified Wilkinson power divider feeding network.Design/methodology/approachThe two covering bands of this planar array antenna are achieved by an Elephant trunk shape (ETS) radiating element; therefore, two frequency bands for Bluetooth (2.4 GHz) and the wireless local area network (WLAN) band (5.15-5.825 GHz) are obtained.FindingsAn improved design of the power divider with curved corners rather than the sharp edges and certain new modifications in the length of matching stubs are implemented.Originality/valueThis paper describes an improved four-way Wilkinson power divider with excellent loss of insertion and adequate return loss for all ports and good isolation performance within two frequency bands (2.4 and 5.5 GHz) and when loaded with array components; the modified power divider complies with the design requirements. To comprehend its behavior, numerical and experimental results are provided. The simulated and measured results indicate a proper bandwidth coverage of the suggested antenna, stable radiation patterns and high gain.

The Smallest Form Factor Monopole Antenna with Meandered Radiator for WLAN and WiMAX Applications

ABSTRACT The demand for designing antennas having multiband operations along with very compact dimensions is increased recently. Compact and low-profile antennas are required which can be used with multiple communication standards in a portable device. This work presents the smallest form factor multiband antenna, which is very compact, low profile, and covers triple-band for wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) applications, simultaneously. The proposed smallest form factor antenna comprises two asymmetric meandered-shaped elements and a partial ground plane for triple-band operations. Designed on a standard and low-cost FR4 substrate, the physical size of the antenna is 20 × 20 mm2 equivalent to 0.15 λ ° × 0.15 λ ° that has been found to be resonating in three bands, i.e. 2.4–2.53, 3.3–4.15, and 5.13–6.2 GHz. An experimental prototype shows that the antenna is satisfying the WLAN (2.40/5.20/5.80 GHz) bands and WiMAX (3.50/5.50 GHz) frequency bands and exhibits acceptable gain in the passbands, good radiation performance and advantageous radiation patterns in the resonant frequencies. The proposed smallest form factor antenna will establish its place for future wireless communication with its promising compactness and extraordinary performance.