Wireless Local Area Network Band Research Articles

A compact UWB MIMO antenna augmented with isolation improvement structures in situ with ground stubs and slots

Abstract An orthogonally oriented microstrip-fed bi-element ultra-wideband (UWB) diversity antenna possessing a super-wide bandwidth, high isolation, and band rejection attributes is proposed. The intended diversity antenna uses a 2nd-order Cayley fractal tree-shaped neutralization line among a pair of radiating square monopoles along with additional components like extended ground stubs, hybrid Koch fractal parasitic elements, and an L-shaped defected ground structure to attain high isolation of <−20 dB over 3.1–18 GHz. To nullify the intervention from the existent wireless local area network band, a hybrid Koch–Minkowski slot is carved out from the radiators. A minimal inter-element spacing of 8 mm is attained with the suggested layout measuring 28 mm (L) × 42 mm (W) in extent. The numerical as well as experimental investigations of vital diversity attributes like the envelope correlation coefficient, mean effective gain, total active reflection coefficient, and multiplexing efficiency depict high diversity actualization. The consistency amidst the simulation as well as the empirical results recommends the worthiness of the intended antenna for handy UWB and UWB multiple-input multiple-output systems.

Wideband single‐fed circularly polarised patch antenna

AbstractA two‐layered wideband single‐fed circularly polarised (CP) antenna is presented by the authors. A single‐fed corner‐truncated square patch with four identical rectangular matching branches acts as a bottom‐driven patch to generate CP radiation. To broaden the 3‐dB axial ratio (AR) bandwidth, a similar patch with a larger size is loaded atop the driven patch as a parasitic patch. The measured results show that the proposed CP antenna has a 17.9% impedance bandwidth from 2.13 to 2.55 GHz and an 11% 3‐dB AR bandwidth from 2.15 to 2.4 GHz, respectively. The measured total gain is 7.1 dBic. The results indicate that the proposed antenna is a good candidate for Wireless Local Area Network band applications.

EMC Hybrid Loop/Monopole LDS Antenna With Three-Sided Ground Walls for 2.4/5/6 GHz WLAN Operation

A multi-resonant, electromagnetic-compatible (EMC), hybrid laser- direct-structuring (LDS) antenna capable of operating in the 2.4, 5, and new 6 GHz wireless local area network (WLAN) bands is presented. The LDS metal patterns are formed on a holder with the volume of 8 mm × 10 mm × 30 mm and comprise an inner loop, a parasitic strip, and three-sided, vertical ground walls. The fundamental and the first higher-order resonance of the parasitic strip acting as a shorted monopole generate the 2460 and 6460 MHz modes. In addition, two loop modes formed by the inner loop with the parasitic strip and the inner loop only, respectively, contribute to the 5420 and 7020 MHz resonance. All of these together generate a tri-WLAN-band, 2.4/5/6 GHz operation. The vertical ground also functions as the shielding walls that assorted conductive components can be placed in the close vicinity of the design for compact integration. The proposed antenna applied to laptop computers for the most recent Wi-Fi 6E operation is demonstrated in this article.

Design of single‐layer bandstop fractal frequency selective surface based on WLAN applications

AbstractIn this letter, we present a new frequency selective surface (FSS) for shielding 2.4–2.5 and 4.98–5.825 GHz wireless local area network (WLAN) bands. This FSS structure is based on the traditional Sierpinski octagon and we improve it. Compared with the traditional structure, the improved one has a smaller element size and better angular stability. The design is realized on float glass with a relative permittivity () of 8, and the unit cell size is 0.1152λ0 × 0.1152λ0 (λ0 is the free space wavelength at the first resonant frequency). Wide rejection bandwidths (−10 dB) of 910 and 1630 MHz are obtained at 2.4–2.5 and 4.98–5.825 GHz, respectively. The surface current distribution and the equivalent circuit model are illustrated to explain the resonance behavior of the proposed FSS. Furthermore, this FSS exhibits stable frequency response to incident angles of 0°–80° under transverse electric and transverse magnetic polarizations. Finally, this FSS structure was fabricated and measured. The measured results demonstrate that this FSS structure has good performance in WLAN applications.

A Dual-Band MIMO Antenna System for 2.4/5 GHz WLAN Applications

A compact multiple-input-multiple-output (MIMO) microstrip antenna system covering the 2.4- and 5- GHz wireless local area network (WLAN) bands is presented in this paper. To achieve dual-band characteristic, the TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01</sub> and TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">03</sub> modes of a microstrip antenna are excited. A rectangular slot is etched in the center of microstrip antenna for improving the radiation capability of the TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">03</sub> mode. Then, two probes are utilized to tune the resonant frequency of the TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01</sub> mode with limited effect on the operating frequency of the TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">03</sub> mode. To realize high inter-port isolation at the two distinct WLAN bands in a methodological way, isolation enhancement is achieved successively at the lower and upper frequency bands. Two split loops are introduced to reduce the mutual coupling at the 2.4-GHz band. Two dipole elements are added in the rectangular slot to obtain high isolation at the 5-GHz band. The decoupling mechanism of the proposed antenna is detailed analyzed. The proposed antenna system operates at 2.25-2.63 GHz and at 5.14-6.06 GHz. The measured maximum value of mutual coupling between the two ports is less than -15.3 dB at both operating frequency bands.

Wideband Single-Fed Circularly Polarized Stacked Patch Antenna With L-Shaped Stub

A wideband single-fed circularly polarized (CP) stacked patch antenna with an L-shaped stub is presented. The CP antenna is made up of the bottom gradient microstrip transmission line, middle driven patch and top square radiation patch. The driven patch with an L-shaped stub and opening slot can achieve a wideband CP radiation which is different from a conventional patch. The presented CP stacked patch antenna maintains good directional radiation, while featuring wideband CP radiation. The final tested results indicate that the presented CP antenna has significant performance with a −10 -dB impedance bandwidth of 42.1% (4.26-6.53 GHz), a 3-dB AR bandwidth of 26.0% (4.36-5.66 GHz) and broadside peak gain of 8.6 dBic. Moreover, the fifth-generation (5G) N79 band (4.4-5.0 GHz) and 5G wireless local area network (WLAN) band (5.15-5.35 GHz) can be covered by the operating bandwidth of the presented CPantenna.

Dual-Band Decoupling for Two Back-to-Back PIFAs

In this communication, two dual-band back-to-back planar inverted-F antennas (PIFAs) are presented for wireless local area network (WLAN) applications. By simply etching a slot on the PIFA, the PIFA can simultaneously radiate at the WLAN 2.4 GHz (2.4–2.484 GHz) and WLAN 5 GHz (5.15–5.835 GHz) bands. To reduce the mutual coupling at the two independent bands in a guided way, long and short slots are successively engraved on the ground. The detailed decoupling process is given and discussed. The antenna was fabricated and measured. The measured results show that the two PIFAs cover the 2.4 and 5 GHz WLAN bands and the isolation can be improved to higher than 20 dB at the two independent bands.

Design and analysis several band antenna for wireless communication

This article describes the construction of a dual-band planar monopole antenna. A microstrip patch antenna with a feedline impedance of 50 ohm and a patch composed of G-shaped and inverted L-shaped strips is used to make the suggested antenna ultra wideband for frequencies ranging from 3.1 to 10.6 GHz. In order to design the antennas, we need to know the dimensions 40x40x1.6 mm3 and the thickness of the ground plane (0.035 mm) (5.2 GHz). There is a method of altering the present distribution by introducing slots. the proposed worldwide interoperability for microwave access (WiMAX) and wireless local area network (WLAN) bands, with a peak gain of 5.2% and an omnidirectional radiation pattern, suitable for ultra wide band (UWB) were shown to be viable.

A Low-Profile Antenna for On-Body and Off-Body Applications in the Lower and Upper ISM and WLAN Bands

The article presents a Co-planar Waveguide (CPW) fed antenna of a low-profile, simple geometry, and compact size operating at the dual band for ISM and WLAN applications for 5G communication devices. The antenna has a small size of 30 mm × 18 mm × 0.79 mm and is realized using Rogers RT/Duroid 5880 substrate. The proposed dual-band antenna contains a CPW feedline along with the triangular patch. Later on, various stubs are loaded to obtain optimal results. The proposed antenna offers a dual band at 2.4 and 5.4 GHz while covering the impedance bandwidths of 2.25-2.8 GHz for ISM and 5.45-5.65 GHz for WLAN applications, respectively. The proposed antenna design is studied and analyzed using the Electromagnetic (EM) High-Frequency Structure Simulator (HFSSv9) tool, and a hardware prototype is fabricated to verify the simulated results. As the antenna is intended for on-body applications, therefore, Specific Absorption Rate (SAR) analysis is carried out to investigate the Electromagnetic effects of the antenna on the human body. Moreover, a comparison between the proposed dual-band antenna and other relevant works in the literature is presented. The results and comparison of the proposed work with other literary works validate that the proposed dual-band antenna is suitable for future 5G devices working in Industrial, Scientific, Medical (ISM), and Wireless Local Area Network (WLAN) bands.

MUTUAL COUPLING REDUCTION IN STACKED STAR MIMO ANTENNA FOR WLAN AND ITU BAND APPLICATIONS

A two-port novel Stacked Star multiple-input multiple-output (MIMO) antenna with a physical size of 46 &amp;times; 23 &amp;times; 3.2 mm&lt;sup&gt;3&lt;/sup&gt; is proposed. The proposed MIMO is designed for wireless communication applications such as Wireless Local Area Network (WLAN) and International Telecommunication Union (ITU) band resonating at 5.4 and 8.5 GHz, respectively. The Star is designed by using a basic circular antenna, from which Star geometry is constructed with iterations to obtain the desired frequency bands using Rogers RT5880 with a thickness of 1.6 mm for Stacked Star. The Stacked Star structure allows a wide bandwidth at the desired frequencies of 5.2-5.5 GHz and 8.2-8.6 GHz, respectively. To minimize mutual coupling, a T-slot stub is placed between the radiating patches. The proposed structures are simulated using Computer Simulation Technology. The proposed design is fed with proximity feed coupling for good impedance matching. Further, it provides an improved isolation of -8 dB. The important characteristics of the antenna such as reflection coefficients, Voltage Standing Wave Ratio, surface current distributions, and radiation patterns, are examined. In addition to that, MIMO characteristics elements like envelope correlation coefficient (ECC), and diversity gain (DG) and group delay -11.3 and -14.2 ns are investigated. The ECC is less than 0.01, while the DG is near 10 Db, indicating good MIMO performance. The anechoic measurement chamber and Schwarz ZVL vector network were used to measure the target MIMO antenna. The simulated and measured result shows a high degree of similarity so that the proposed antenna is strongly suggested for WLAN and ITU bands.

A Notch-Band UWB Antenna for OAM Wave Generation

This paper investigates a trapezoidal Monopole Patch Antenna (MPA) with an Ultra-Wideband (UWB) characteristic and a dual-stage notched band at fifth generation (5G) and Wireless Local-Area Network (WLAN) bands. The 5G band is notched by inserting a U-shaped slot on the trapezoidal UWB MPA. The WLAN band is notched using five-square metallic-conductor Electromagnetic Bandgap (EBG) patches that are installed on the surface of the backside of the radiating patch and attached to the ground plane via a shorting pin. The small, proposed antenna is built upon an FR4 substrate substance, having dielectric comparative permittivity εr = 4.7, and fed by a 50 Ω coplanar waveguide. The antenna’s size is 32×42.90×0.8 mm3. The simulated results show that the antenna has an operating frequency range of 2.39–14.72 GHz for |S11|&lt;-10 rejecting WLAN (5.15–5.825 GHz), as well as sub-6 GHz 5G (3.4–3.9 GHz) great-selectivity signals. A higher gain obtained by the UWB antenna is 6.4 dBi, while a sharp decrease occurs in the rejected bands, reaching -8.29 dBi. This study also employs the Orbital Angular Momentum (OAM) technique. However, OAM waves are generated using eight trapezoidal UWB MPAs. Creating notches reduces the interference problem in UWB frequencies, and merging the UWB with the OAM technique allows the OAM to operate on many frequencies. Moreover, notches can be generated for specific frequencies inside the UWB bands. These techniques, trapezoidal UWB MPA and OAM wave generation, can significantly increase the spectrum range and improve the spectrum efficiency in wireless communications.

Electromagnetic Band Gap based compact UWB Antenna with Dual Band Notch Response

In Antenna Technology, Electromagnetic Band Gap (EBG) structures are one of the mostly used structures to improve gain of antenna, suppress surface waves and band notching. In UWB frequency spectrum more number of small frequency bands are exists and these bands cause electromagnetic interference, to reject such bands more number of EBG structures are required. Due to limited monopole antenna's ground plane, it is required to have EBG with small in size and single EBG to reject two or more bands. The simulated results of proposed new C-shaped EBG by placing near the feedline of fork-shape Ultra-Wide Band (UWB) antenna to reject two bands namely Lower Wireless Local Area Network(L-WLAN) band range from 5.15 GHz to 5.35GHz and X-band of satellite downlink communications networks (7.25GHz –7.75GHz) within a UWB antenna's spectrum and EBG occupying less area compared with the reported Conventional Mushroom Type (CMT) EBG, semi-circular EBG, slotted-patch ELV EBG and TVS EBG. Fabrication and measurement results of the newly proposed antenna attain an enormous bandwidth i.e., from 2.8 GHz to 11.5 GHz while eliminating frequency bands between 5.15 GHz to 5.35 GHz (Lower WLAN) &amp; 7.25GHz to 7.75GHz (X-band of satellite downlink).

A Compact-Size and High-Efficiency Cage Antenna for 2.4-GHz WLAN Access Points

In this communication, a compact-size and high-efficiency air cavity antenna with a cage-like structure is proposed for 2.4 GHz wireless local area networks (WLAN). The air cavity antenna is constructed with four sides of hybrid metallized vias, including sparsely arranged blind vias and tightly arranged shorting vias. First, the antenna size is significantly reduced by utilizing the shorting vias, which makes the antenna operate at the high-order TM <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\mathrm {1/2,1/2}}$ </tex-math></inline-formula> mode. Then, by loading the capacitive blind vias at the radiating apertures, the antenna size is further miniaturized. Notably, high radiation efficiency is obtained attributed to the lower dielectric loss of the air-medium structure. Finally, a prototype of the proposed cage antenna has been fabricated and tested with good agreement between simulated and measured results. In such a compact size of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.128\lambda _{0} \times 0.128 \lambda _{0} \times 0.10 \lambda _{0}$ </tex-math></inline-formula> ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda _{0}$ </tex-math></inline-formula> is the free-space wavelength at the center frequency), the measured total efficiency over 90% is achieved in the WLAN band by the cage structure. Compared with the existing 2.4 GHz antennas, the proposed one is with the ascendency of compact size and high radiating efficiency for WLAN applications.

An EBG-Based Triple-Band Wearable Antenna for WBAN Applications.

In this article, a triple-band wearable monopole antenna fed by a coplanar waveguide (CPW) with an integrated electromagnetic bandgap (EBG) array is proposed. The monopole antenna consists of an asymmetric inverted U-shaped strip, a horizontal branch, and an L-shaped ground stub, which can generate the 2.45/5.8 GHz wireless local area network (WLAN) band and the 3.5 GHz worldwide interoperability for microwave access (WiMAX) band. To reduce the influence of antenna radiation on the human body, a triple-band 3 × 3 EBG array has been integrated into the back of the monopole antenna. The EBG unit is composed of two rectangular rings and a circular ring, and the operating frequencies correspond to the triple bands of the monopole antenna. In this paper, the impedance and radiation performances of the stand-alone monopole antenna and the integrated antenna are analyzed, and the safety for the human body is evaluated based on specific absorption rate (SAR) values. The proposed triple-band antenna can be used in wearable devices in wireless body area networks (WBANs).

A photopaper‐based low‐cost, wideband wearable antenna for wireless body area network applications

This study presents a low-cost, compact, flexible, and wideband wearable antenna for different wireless body area network (WBAN) band applications, covering medical body area network band of 2.4 GHz, industrial, scientific, and medical band of 2.45 GHz, WiMAX band of 3.5 GHz, and wireless local area network band of 5.2 GHz. The final antenna topology is obtained by hexagonal microstrip radiator patch fabricated on commercially available low-cost photo paper substrate and defected ground plane below the feed line acting as a partial ground to achieve a conformable structure wideband operation. The overall size of the fabricated antenna is 30 × 40 mm2 and yields a wide-bandwidth of 3 GHz (2.30–5.30 GHz), radiation efficiency of 84.35%, and the highest gain of 3.48 dBi at the centre frequency of 5.2 GHz, and minimum gain of 1.91 dBi at 2.45 GHz. Furthermore, our detailed numerical and experimental investigations involving specific absorption rate performance assessment and bending analysis revealed the proposed design's excellent robustness to both human body loading and structural deformation scenarios. Therefore, simulated and measured results strongly advocate that the proposed design has profound implications for flexible and body-worn devices in WBAN applications.

Compact UWB MIMO antenna with dual band-notch characteristics

ABSTRACT This article describes a quad-port ultra-wideband multiple-input multiple-output (MIMO) antenna with dual-band notch characteristics that is very compact and highly isolated. The compactness and high isolation of this design are achieved by etching a modified Minkowski fractal structure and an inverted L-shaped stub made available by the partial ground plane. Simply by incorporating ‘C’- and ‘U’-shaped slots in the radiating patch, it is possible to obtain dual-band rejection characteristics that are very suitable for wireless local area network band and X-band downlink satellite communication of 5.0–5.9 GHz and 7.1–7.9 GHz, respectively, in this proposed structure. The entire design is housed in a very compact size of 30 mm × 30 mm. A few key parameters, such as channel capacity loss (CCL), envelope correlation coefficient (ECC), diversity gain (DG) and total active reflection coefficient (TARC), are examined to ensure that the MIMO system meets its requirements. Furthermore, a mutual coupling value of less than −22 dB and an operating frequency band of 3.1–12 GHz allow the design to be very effective in a multipath channel environment.

Development of a Numerical Tablet Model in WLAN Band for SAR Study

This research proposes a numerical model for a tablet in the wireless local area network band for specific absorption rate (SAR) study. The design criteria, such as the tablet size, operating frequencies, antenna position, and target 1-g peak spatial-average SAR (psSAR) values in the flat phantom, are determined based on the SAR test reports of tablets distributed in South Korea from 2013 to 2017. An internal antenna is designed in a tablet platform to operate in dual bands of 2,450 MHz and 5,500 MHz. The numerical results illustrate that the 1-g psSAR values of the proposed numerical tablet model are within ±10% of the target values. Moreover, the return loss of the designed tablet model is larger than 10 dB, regardless of flat phantom, while its radiation efficiency is higher than 90% in free space.

Multiband Dual-Polarized Hybrid Antenna With Complementary Beam for Simultaneous RF Energy Harvesting and WPT

A novel hybrid antenna for simultaneous RF energy harvesting (RF-EH) and dedicated wireless power transfer (WPT) is proposed. The hybrid antenna consists of a multiband dual-polarized omnidirectional antenna element (covering GSM-1800, UMTS-2100, ISM-2400/5800, 5G-3500, and wireless local area network (WLAN) bands) and a 2.4 GHz dual-polarized high-gain directional patch array element. In the WPT band (ISM-2400), directional beams locate at the null of omnidirectional beams, and a pair of spatially complementary beams is obtained. The omnidirectional beams are capable of capturing the ambient RF energy from low-elevation space for low-power circuits, while the directional beams receive the power from a dedicated source to activate high-power modules. Also, the spatially complementary feature contributes low mutual couplings between ports that support the independent operation of WPT and RF-EH. For validation, an outdoor RF-EH test and an indoor WPT test are conducted. The measured results agree with the simulated ones.

Multi-band frequency reconfigurable antenna using EBG and parasitic patches

ABSTRACT This article demonstrated a compact reconfigurable microstrip antenna with a multi-band configuration. It resonates for three different frequency configurations, including the single and dual bands. The primary rectangular patch antenna resonates for WLAN (5.2 GHz center frequency) band. The reconfigurable electromagnetic bandgap (EBG) and parasitic patches near the feed line produce 4 and 6.33 GHz resonance. The defected ground structure is integrated with a PIN diode to make reconfigurable EBG, and it resonated at C band (4 GHz). The PIN diode switching configuration embedded with EBG and one square patch creates dual-band characteristics in wireless local-area network (WLAN) and International Telecommunication Union (ITU) bands. Other PIN diodes switching configurations with primary antenna and two other patches work for C and WLAN bands. The proposed antenna resonated at 4, 5.2, and 6.33 GHz frequencies with different switching configurations of the PIN diode. The simulated results of this novel antenna configuration verified with measured consequences for antenna parameters like reflection coefficient and radiation characteristics are also presented.

Textile Via-Loaded Bandwidth-Enhanced Half-Mode Substrate-Integrated Cavity Antenna for WLAN Communications

A textile via-loaded bandwidth-enhanced half-mode substrate-integrated cavity (HMSIC) antenna is presented in this article for wireless local area network (WLAN) communications. A strategy for adding shorting vias within the cavity is proposed based on the simulated <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${E}$ </tex-math></inline-formula> -field distributions of different modes of the HMSIC antenna. More specifically, the number and positions of vias are studied for maximum shift of lower resonance ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\rm TM_{1,1,0}^{HM}$ </tex-math></inline-formula> mode) so that it merges with higher resonance (rotated <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\rm TM_{2,2,0}^{HM}$ </tex-math></inline-formula> mode) to achieve a wide 10 dB return loss impedance band. Two prototypes of the designed structure are realized using textile manufacture techniques. A first realization uses embroidered sidewalls to create the cavity and metallic rivets for the shorting vias, and a second prototype uses embroidered vias and a stripline feed. The proposed antenna can operate from 5.09 to 5.9 GHz with a fractional bandwidth of 14.7% according to measurements. The simulated radiation efficiency is above 95% in free space and 82% when worn on the human body in the 5 GHz WLAN band (5.15–5.825 GHz).