Wireless Local Area Network Band Research Articles

Systematic Investigation from Material Characterization to Modeling of Jute-Substrate-Based Conformal Circularly Polarized Wearable Antenna

This study considers emerging trends to develop a textile-based circularly polarized (CP) conformal textile antenna on jute textile material as a natural fiber substrate due to its durability, ecofriendliness, and skin-friendly nature. The jute fabric material was subject to extensive study by scanning electron microscopy to compared it with other, related materials such as cotton and silk. Considering the infeasibility of using cotton or silk, jute textile is considered to be an effective textile substrate due to its active fiber interaction, low level of noncellulose impurities, and excellent antistatic properties. The topology of the proposed textile antenna is inspired by the tai chi symbol, where the main radiating structure has a semicircular shape and the ground structure include a similar form but complementary to the main radiating element. Industrial-grade conductive copper paint was used to achieve conducting radiating elements. The designed antenna resonates with circular polarization (CP) at 3.5 GHz, 4.9 GHz, and 5.8 GHz in the Worldwide Interoperability for Microwave Access, wireless local area network, and industrial, scientific, and medical radio bands. The variations of the resonant frequencies, axial ratios, and surface current distributions of the textile-based antenna were systematically investigated with bending at different angles to evaluate its use in body-mounted 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.

Reconfigurable 2.4-/5-GHz Dual-Band Transmitter Front-End Supporting 1024-QAM for WLAN 802.11ax Application in 40-nm CMOS

This article presents a new design methodology of a reconfigurable dual-band output matching network with high efficiency. The implemented output matching network achieves a passive efficiency of 71.6% and 75% at 2.4 and 5.5 GHz, respectively. Based on the proposed output matching network, a transmitter and a standalone power amplifier (PA) supporting 2.4-/5-GHz dual-band operation for the emerging wireless local area network (WLAN) 802.11ax application are designed and fabricated in 40-nm CMOS technology. In 2.4- and 5-GHz WLAN bands, the PA achieves a P sat of 23 and 21.9-22.4 dBm with power-added efficiency (PAE) of 27% and 24.2%-28.2%, respectively. At 2.442 GHz, the transmitter delivers 8.1-dBm average output power for 40-MHz, 1024-quadrature amplitude modulation (QAM) 802.11ax signal while meeting the standard specification of error vector magnitude (EVM) below -35 dB. In 5-GHz operating mode, the transmitter achieves an average output power of 6.72-6.95 dBm with the EVM of -35 dB for 80-MHz, 1024-QAM 802.11ax signal. The PA and transmitter front end are the first published designs for dual-band WLAN 802.11ax application in the literature.

Broadband circularly polarized printed falcate‐shaped monopole antenna

In this study, a simple broadband circularly polarized (CP) printed monopole antenna for S/C-band applications is proposed. The CP antenna is composed of a falcate-shaped monopole with a right-angle trapezoid stub, then wide impedance and axial ratio (AR) bandwidths are achieved. By placing one rectangular split-ring resonator above the stub for generating upper CP mode, both of impedance and CP performances are further improved. The proposed antenna is fabricated on a FR4 substrate and measured. The measured −10-dB impedance bandwidth is 107%, ranging from 2.4-7.9 GHz, and the measured 3-dB AR bandwidth is 94% (2.4-6.6 GHz), covering the entire wireless local area network (WLAN) and WiMAX bands.

High-Gain SIR Dual-Band Antenna Based on CSRR-Enhanced SIW for 2.4/5.2/5.8 GHz WLAN

This paper presents a dual-band step impedance resonator (SIR) antenna based on metamaterial-inspired periodic structure of coupled complementary split-ring resonators substrate-integrated waveguide (CSRR-SIW). The antenna supports wireless local area networks (WLAN) bands at 2.4/5.2/5.8 GHz. The CSRRs and two branches of the SIR element are etched on the top and bottom metal surfaces of the substrate. The SIR element produces a fundamental frequency f1 at 2.4 GHz and a second harmonic frequency fs2 at 5.7 GHz. Meanwhile, the CSRRs produces a resonant frequency at high-frequency band around 5.2 GHz, which can be combined with the second harmonic frequency fs2 at 5.7 GHz. The high-frequency bandwidth can then be broadened. The simulated and measured results show that the dual operation bands with bandwidths of 16% from 2.25 GHz to 2.64 GHz and 18.2% from 5 GHz to 6 GHz for |S11| < −10 dB are achieved. Meanwhile, the proposed antenna has peak gains ranging from 6.5 dBi to 7 dBi and from 7 dBi to 7.7 dBi in the lower and upper bands, respectively. Compared with many previously reported dual-band antenna designs, the proposed antenna achieves comparable bandwidth performance and larger gain per unit area with a relatively smaller size. Moreover, the simple structure renders the proposed antenna has the advantage of easy-processable and cost-effective implementation.

Electromagnetic bandgap structure and split ring slot‐based monopole antenna for ultra‐wideband applications with dual band notch characteristics

AbstractReduced lightweight microstrip patch antennas have attracted considerable attention in ultra‐wideband (UWB) applications. In this article, a novel modified circular ultra‐wideband monopole antenna with dual‐band notch characteristics is proposed. A circular split‐ring slot and a mushroom‐electromagnetic bandgap‐type structure are employed to realize the dual‐band notch characteristics. The proposed antenna exhibits the bandwidth of 2.0‐12 GHz with a Voltage Standing Wave Ratio <2 except at the WiMAX band of 3.2‐3.7 GHz and wireless local area network band of 5.1‐5.8 GHz. The simulated and measured results of the proposed antenna, along with the design parameters, are reported and discussed in detail. The results show that the antenna is suitable for UWB applications.

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.

Compact CPW‐fed circular patch flexible antenna for super‐wideband applications

This study proposes a coplanar waveguide-fed circular monopole antenna that is designed by ink-jetting conductive silver particle ink on photo paper. The antenna comprises a slotted circular patch and a reduced symmetrically slotted ground plane that is etched rectangularly. The slotted circular patch and ground plane provide the design flexibility with a broad bandwidth, substantial gain over 1.66–56.1 GHz frequency band, and relatively consistent radiation pattern. The fractional bandwidth (%BW) of this antenna is 188.5% that is covering industrial, scientific, and medical (ISM) bands, ultra-wideband, wireless local area network (WLAN) band, worldwide interoperability for microwave access (WiMAX) band, and various frequencies of upcoming fifth-generation technology. The total size of the antenna is only 34 × 25 mm2, with an electrical dimension of 0.18 λ × 0.13 λ at 1.66 GHz. The bandwidth ratio (BR) is 33.81:1, and the bandwidth dimension ratio (BDR) is 7462, which is the highest among the flexible super-wideband antennas reported so far. It is a low profile, lightweight, and low-cost antenna that is accommodating a broad frequency spectrum for extended wideband communication. The measured results show good agreement with the simulations.

An ultra-thin, dual band, Sub 6 GHz, 5G and WLAN antenna for next generation laptop computers

PurposeThe purpose of this manuscript is to present a novel, compact and ultra-thin “3”-shaped monopole antenna for wireless operations in the laptop computer. The thickness of the antenna is only 0.2 mm and is designed using only a pure copper strip of size 17.5 × 6 mm2.Design/methodology/approachThe simple structure of the proposed antenna consists of two monopole radiating strips, namely, AC and CD and an open-ended rectangular tuning stub BE of length 9mm.FindingsThis structure inspires two resonating modes at 3.45 and 5.5 GHz and achieves the measured impedance band width as 20% (3.21-3.91) GHz in lower band (F_l) and 15% (5.05-5.85) GHz in the upper band (F_u) for voltage standing wave ratio < 2. These two bands cover 5GHz wireless local area network (WLAN) and 3.3-3.6GHz (sub 6GHz) 5G bands. The measured radiation performance including, nearly omnidirectional radiation patterns, a stable gain of around 5 dBi and excellent efficiency around 90% in both operating bands have been achieved. Furthermore, a simplified equivalent circuit model has been derived and its simulation is performed. The simulated and measured results are in good agreement, which demonstrates the applicability of the antenna structure for WiMAX/WLAN operations in the prominent ultra-thin laptop computers.Originality/valueThe proposed antenna is designed without using any reactive elements, vias or matching circuits for excitation of WLAN and 5G bands in the laptop computers. The design also does not require any additional ground for mounting the antenna. The proposed antenna has a very low profile, is ultra-thin, cost-effective, easy to manufacture and can be easily embedded inside next generation laptop computers.

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.

Integrated planar inverted-F antenna on laptop computer’s hinge for 2.4/5.2/5.8-GHz WLAN operation

ABSTRACTA compact planar inverted-F antenna (PIFA) placed on one of the two hinges of a laptop computer is proposed for wireless local-area network (WLAN) operation. The aim of this design is to integrate the PIFA’s metal surroundings as part of the radiating structure. When the PIFA is fed, resonant modes in the hinge slot bounded by the two hinges, display ground plane, and keyboard ground plane can in turn be excited. Since the 200 × 5 mm2 slot is much larger than the 10 × 5 mm2 PIFA itself, the latter, although compact and structurally simple, can be made efficiently radiating with the help of the former. Measured efficiencies are all over 50% in the desired three WLAN bands

A Compact Self-Triplexing Antenna Using HMSIW Cavity

In this letter, a novel design of compact self-triplexing antenna using half-mode substrate integrated waveguide (HMSIW) cavity for triple-band applications is presented. In the proposed antenna, an inverted V-shaped slot is inserted on the top surface of a rectangular HMSIW cavity and three individual microstrip feedlines are used to excite three separate modes at three different wireless local area network (WLAN) bands around 4.95, 5.3, and 5.9 GHz. Due to use of HMSIW cavity, the size of antenna has become compact. The measured isolation of the antenna in between any two ports is better than 20.5 dB in such a compact structure. The measured gains at three frequencies 4.95, 5.3, and 5.9 GHz are 4.5, 4.9, and 6.1 dBi, respectively. The efficiency of antenna is better than 84% in all the bands. The separation between co-to-cross-polarization levels is more than 19 dB, and front-to-back ratio (FTBR) is better than 14 dB at each band. Moreover, any band of antenna can be tuned independently by keeping other bands almost intact.

Mutual coupling reduction in Chinese character‐shaped artistic MIMO antenna

AbstractIn this paper, a Chinese character‐shaped artistic multiple input multiple output (MIMO) antenna with H‐shaped defect ground structure (HDGS) is designed and analyzed. The H‐shaped structures are loaded on the ground along the outer edge of patches to make it a part of the coupling current propagation direction. The two‐element MIMO antenna is placed on the substrate with a separation of only 0.024 λ0 (λ0 is the free‐space wavelength at 2.458 GHz). The designed MIMO antenna without HDGS has 10.4 and 7.2 dB higher isolation than E‐ and H‐plane rectangular array antennas. After loading HDGS, the isolation reaches 23.86 dB at 2.458 GHz, and the center frequency is not offset. The achieved bandwidth is within IEEE 802.11 at a 2.4‐GHz wireless local area network band. Meanwhile, the isolation is higher than 20 dB in the 10‐dB impedance bandwidth (2.447‐2.468 GHz). Moreover, the radiation pattern remained basically unchanged.

Broadband planar slot antenna using a simple single‐layer FSS stopband

In this study, the authors propose a simple structure of a new broadband planar slot antenna using a wide single-layer frequency selective surface (FSS) stopband. The proposed design is realised in two stages. First, the performances of the FSS unit cells are investigated using the finite element method of high-frequency structure simulator. Besides, the FSS structure considered as a stop-band filter in the bandwidth , is also validated by computer simulation technology microwave studio. Second, this FSS reflector is combined with a miniaturised wideband planar slot antenna . The final proposed combination is also designed, optimised, fabricated and validated by measurements. The obtained results show an operating impedance bandwidth of including the Worldwide interoperability for Microwave Access band, the C band for satellite applications, and the Wireless Local Area Network band. Furthermore, the antenna provides an measured maximum gain. Compared to the same antenna without FSS, a maximum gain enhancement of is achieved by the proposed structure. In addition, the back lobes are reduced in the proposed structure by , compared to a simple antenna. The total size of the proposed antenna, integrating the FSS, is .

Compact reconfigurable triple notch ultra-wideband bandpass filter for cognitive radio system

This paper introduces a compact ultra-wideband (UWB) bandpass filter (BPF) with two switchable external notch structures which avoids the interference between the UWB communication with worldwide interoperability for microwave access (WiMAX) and wireless local area network (WLAN) systems, suitable for cognitive radio (CR) applications. The first external notch structure is modified C-shaped structure which generates a sharp rejection at 3.5 GHz to avoid interference with WiMAX system and second external notch structure is back to back T-shaped structure which creates sharp rejection notch bands at 5.2 GHz and 5.8 GHz frequencies for WLAN systems. The filter reconfiguration is achieved by varying the conductance of microstrip line. The response of the proposed structure shows sharp rejections at one WiMAX and two WLAN bands. The bandpass filter covers frequency of UWB system from 3.1 to 10.7 GHz having very low passband insertion loss. The proposed UWB BPF is designed, simulated, fabricated and tested to validate the results. A good agreement is achieved between simulation and experimental results.

Compact reconfigurable triple notch ultra-wideband bandpass filter for cognitive radio system

This paper introduces a compact ultra-wideband (UWB) bandpass filter (BPF) with two switchable external notch structures which avoids the interference between the UWB communication with worldwide interoperability for microwave access (WiMAX) and wireless local area network (WLAN) systems, suitable for cognitive radio (CR) applications. The first external notch structure is modified C-shaped structure which generates a sharp rejection at 3.5 GHz to avoid interference with WiMAX system and second external notch structure is back to back T-shaped structure which creates sharp rejection notch bands at 5.2 GHz and 5.8 GHz frequencies for WLAN systems. The filter reconfiguration is achieved by varying the conductance of microstrip line. The response of the proposed structure shows sharp rejections at one WiMAX and two WLAN bands. The bandpass filter covers frequency of UWB system from 3.1 to 10.7 GHz having very low passband insertion loss. The proposed UWB BPF is designed, simulated, fabricated and tested to validate the results. A good agreement is achieved between simulation and experimental results.

Eight-Element Compact UWB-MIMO/Diversity Antenna with WLAN Band Rejection for 3G/4G/5G Communications

An eight element, compact Ultra Wideband-Multiple Input Multiple Output (UWB-MIMO) antenna capable of providing high data rates for future Fifth Generation (5G) terminal equipments along with the provision of necessary bandwidth for Third Generation (3G) and Fourth Generation (4G) communications that accomplishes band rejection from 4.85 to 6.35 GHz by deploying a Inductor Capacitor (LC) stub on the ground plane is presented. The incorporated stub also provides flexibility to reject any selected band as well as bandwidth control. The orthogonal placement of the printed monopoles permits polarization diversity and provides high isolation. In the proposed eight element UWB-MIMO/diversity antenna, monopole pair 3-4 are 180o mirrored transform of monopole pair 1-2 which lie on the opposite corners of a planar 50 x 50 mm2 substrate. Four additional monopoles are then placed perpendicularly to the same board leading to a total size of 50 x 50 x 25 mm3 only. The simulated results are validated by comparing the measurements of a fabricated prototype. It was concluded that the design meets the target specifications over the entire bandwidth of 2 to 12 GHz with a reflection coefficient better than -10 dB (except the rejected band), isolation more than 17 dB, low envelope correlation, low gain variation, stable radiation pattern, and strong rejection of the signals in the Wireless Local Area Network (WLAN) band. Overall, compact and reduced complexity of the proposed eight element architecture, strengthens its practical viability for the diversity applications in future 5G terminal equipments amongst other MIMO antennas designs present in the literature.

Dual Annular Ring Coupled Stacked Psi Shape Patch Antenna for Wireless Applications

The paper aims to design and analyze an annular ring coupled stacked Psi shaped patch antenna with coplanar waveguide (CPW) feed technique operating for dual band frequency applications. The proposed model comprises of stacked Psi shapes resonating for lower order frequency. The second order resonating band was obtained through capacitively coupled overlapped annular rings. The geometrical dimensions of the proposed model are 3.5*2 (L*W) based on lower order resonating band. The design and simulations were performed using DS CST Microwave Studio suite. The model achieves dual resonant bands, (2.19- 2.68) GHz with impedance bandwidth 490 MHz and (5.569 – 6.09) GHz with 530 MHz impedance bandwidth. The center frequencies are 2.42 GHz and 5.815 GHz with return loss -28.97 dB and -28.99 dB respectively. The design exhibited a maximum gain of 5 dB with bidirectional and omni directional patterns in E and H- planes. The axial ratio at the two resonating bands was less than 3 dB. Parametric analysis was performed for reflection co-efficient on geometric variables like ground width, ground length and permittivity. From (3-5) GHz frequency range, a perfect notch band was also exhibited. Simulated and measured results have shown a good concurrence. The model was suitable for WLAN (Wireless Local Area Network) and ISM (Industrial, Scientific and Medical) Band applications.

Design of Smartwatch Integrated Antenna With Polarization Diversity

A design of smartwatch integrated antenna with polarization diversity is proposed. An annular ring is integrated in the framework of smartwatch, and excited by two ports. One port is fed by a coplanar waveguide (CPW) line loaded with a T-shaped matching network, and the other is fed by a coplanar strip line (CPS). The overall model of the proposed antenna has a cylindrical shape with 38 mm diameter and 7.5 mm thickness. A metallic plate is located at the backside of the antenna to mimic the shell of smartwatch. The prototype is fabricated and measured, and the measured results agree well with the numerical ones. The two ports have orthometric radiation patterns and can cover the 2.4 GHz wireless local area network (WLAN) band. The gain of the antenna is higher than 3.2 dBi in free space. The proposed antenna is also analyzed with a cubic tissue model and a wrist model in different distances between the proposed antenna and human models. The performances on body scenarios are also acceptable. The values of specific absorption rate (SAR) in the cubic tissue model and wrist model are below the limitations set by both the Federal Communication Commission (FCC) and the European Telecommunication Standards Institute (ETSI). Envelope correlation coefficient (ECC) shows proposed antenna can be used in multiple input multiple output (MIMO) applications. The influence of battery and printed circuits board assembly (PCBA) on S parameters is obvious, and gain and radiation efficiency are not much affected.

Development of Robust Transparent Conformal Antennas Based on Conductive Mesh-Polymer Composite for Unobtrusive Wearable Applications

In this paper, a detailed investigation of the realization of conformal wearable transparent antennas by integrating conductive mesh with polymer has been presented. The proposed realization method is much simpler and more cost-effective than the existing realization methods of transparent antennas, and the prototype fabricated from the selected composite materials is more flexible and robust in bending operations than other transparent antennas. In this paper, the mechanical, electrical, and optical characteristics of the proposed composite material have been investigated to analyze its suitability for transparent flexible antenna realization. For concept demonstration, a prototype of a dual-band antenna operating at 2.33–2.53 GHz and 4.7–5.6 GHz has been fabricated and tested. These frequencies cover both the instrument, scientific, and measurement (ISM) and the wireless local area network (WLAN) bands. Full ground plane is utilized in the antenna design for on-body operations. The suitability of the antenna for wearable applications has been investigated by measuring its performance under physical deformation and testing its performance on phantom. Next, the RF performance of the antenna has been improved by using two layers of conductor to form the radiating element. Although transparency is slightly compromised, the double-layer element improves the gain and efficiency of the antenna.