WLAN Frequency Bands Research Articles

Multi-frequency composite wearable antenna for wireless communications

This paper proposes a multi-band composite wearable antenna for wireless communication, which uses a monopole structure as the radiating body and achieves multi-band characteristics through slit-loading and multi-branching methods. A polymer composite substrate with high dielectric constant and low dielectric loss was prepared using in situ polymerization, and the optimal dielectric constant and loss angle tangent were obtained by controlling the coating ratio of melamine formaldehyde resin to carbon nanotubes (MWCNTs) and the filler doping rate to achieve miniaturization of the antenna. Comparative experimental results show that the obtained composites have high flexibility and good dielectric properties. The antenna operates in the frequency bands of 2.21–2.52 GHz, 3.07–3.87 GHz, and 4.36–6.03 GHz, which cover the frequency bands of WLAN and WiMAX and 5G applications. The antenna was fabricated and tested, and its performance roughly matched the simulation results. Meanwhile, the antenna has passed the SAR safety test and maintained a stable performance under different curvatures, so it has potential applications in the wireless communication system.

Mutual coupling suppression of MIMO array with non-uniform curved-strip EBG structure via shape and layout co-optimization

In this paper, a shape and layout co-optimization method for mutual coupling suppression of MIMO array with non-uniform curved-strip electromagnetic bandgap (EBG) structure is proposed. The curved shape of the EBG structure between the microstrip patches is described to achieve the mutual coupling suppression by the spline curve and moving it the same displacement along the y-axis in both directions, where the spline curve is formed by the coordinates of the control points corresponding to the Bessel function. Moreover, the non-uniform layout design of the EBG structure is introduced to further adjust the radiation field and the surface current distribution of the coupled array. Through simultaneously optimizing the curved shape and layout parameters of the strip EBG structure, the expected array radiation and decoupling performances are obtained. The effectiveness of the proposed method is validated by a MIMO array with edge-to-edge distance of only 0.1λ0 in the 5G WLAN frequency band. The simulation and experiment results indicate that, compared with non-EBG and the initial uniform strip EBG, the proposed EBG structure can provide the advantage of significantly reducing the mutual coupling to −35.20 dB and effectively improving the isolation between the elements, meanwhile ensuring the MIMO array performances.

An Ultra-Wideband Antenna with Triple Band-Notched Characteristics for Wearable Application

This work presents a compact UWB antenna with triple band-notched at WiMAX (3.2 GHz to 3.7 GHz), C-band (3.7 GHz to 4.2 GHz) and WLAN (5.15 GHz to 5.35 GHz) for wearable applications. The UWB antenna is fabricated on a semi-flexible thin FR-4 substrate. In order to reduce the complexity, only two slots are introduced on the radiating patch instead of three slots to reject each narrow band frequency. In this case, one slot rejects a combination of WiMAX and C-band and the other slot rejects the WLAN frequency band. The UWB antenna on the thin FR-4 material has an overall size of 21×16 mm2, which is very compact and thus, suitable for wearable applications without causing discomfort when worn on-body. Although the antenna is small in size, the performance is not compromised. The UWB antenna has the frequency range from 2.51 GHz to 12.09 GHz, maximum radiation efficiency of 100% and maximum gain of 4 dBi. Nevertheless, the antenna is able to reject the WiMAX and C-band as well as the WLAN band. The simulated specific absorption rate (SAR) results show that the antenna complies with the SAR limit Federal Communication Commission (FCC) and International Commission of Non-Ionizing Radiation Protections (ICNIRP) standards for 1 mW input power. Bending investigations performed on different diameters of Styrofoam cylinders shows that the frequency range and the notch bands are not very much affected.

Broadband CP corner-truncated microstrip antenna with irregularly hexagonal AMC for 2.45 GHz applications

This research proposes a compact broadband circularly polarized (CP) corner-truncated microstrip antenna with irregularly hexagonal artificial magnetic conductor (AMC) for 2.45 GHz WLAN applications. The corners of the radiating patch are diagonally truncated to realize circular polarization and improve axial ratio. A 5▪5 irregularly hexagonal AMC array is employed to enhance the axial ratio bandwidth (ARBW) and antenna gain. In addition, a tri-section meandering feedline is used to realize impedance matching and improve the impedance bandwidth (IBW). The AMC array is used to manipulate electromagnetic waves by suppressing surface currents and back lobe, resulting in reduced back radiation and enhanced front-to-back ratio. The simulated IBW and ARBW are 50.9% (1.86 – 3.13 GHz) and 19.3% (2.24 – 2.72 GHz) respectively, with a maximum gain of 8.9 dBic at 2.45 GHz. The measured IBW and ARBW are 42.42% (1.95 – 3.0 GHz) and 29.4% (2.03 – 2.73 GHz), with a maximum gain of 8.6 dBic. The simulated half power beamwidth (HPBW) of the proposed antenna scheme in the xz plane at 2.24 GHz, 2.45 GHz, and 2.72 GHz are 67°, 62°, and 51°, respectively. The corresponding HPBW in the yz plane are 60°, 55°, and 62°. The simulated AR beamwidth in the xz plane at 2.24 GHz, 2.45 GHz, and 2.72 GHz are 177°, 164°, and 88°, respectively. The corresponding AR beamwidth in the yz plane are 148°, 106°, and 124°. The simulated cross polarized (XP) levels at 2.45 GHz are below -19.35 dB for both planes. The measured HPBW in the xz plane at 2.24 GHz, 2.45 GHz, and 2.72 GHz are 69°, 64°, and 50°, respectively. The corresponding HPBW in the yz plane are 65°, 54°, and 37°. The measured AR beamwidth in the xz plane at 2.24 GHz, 2.45 GHz, and 2.72 GHz are 161°, 200°, and 104°, respectively. The corresponding AR beamwidth in the yz plane are 162°, 85°, and 90°. The measured XP levels at 2.45 GHz are below -15.62 dB for both planes. The radiation pattern is unidirectional. Essentially, the proposed broadband CP antenna scheme is suitable for the WLAN frequency band and other 2.45 GHz wireless communication technologies. The novelty of this research lies in the use of the tri-section meandering feedline and the irregularly hexagonal AMC array to enhance IBW and ARBW.

Multi-Band Coupled-Fed Antenna for 4G LTE, Sub-6G, and WLAN Frequency Bands in Various Electronic Devices

Multi-Band Coupled-Fed Antenna for 4G LTE, Sub-6G, and WLAN Frequency Bands in Various Electronic Devices

Compact dual band 4-port MIMO antenna for 5G-sub 6 GHz/N38/N41/N90 and WLAN frequency bands

In this investigation, a dual-band 4 port MIMO antenna is designed, fabricated and measured. The MIMO design consists of perturbed hexagonal patch along its periphery on the top of the substrate and the connected ground plane on the bottom. The MIMO design has an overall dimension of 50 × 50 × 0.8 mm3. The proposed antenna structure demonstrates the dual frequency band of 2.47–3.38 GHz and 4.94–7.24 GHz, respectively covering the 5G sub-6 GHz/WLAN/HiperLAN band applications. Moreover, the radiation efficiency, gain and far-field patterns are also presented across both the operating bands. The antenna diversity parameters which include ECC, DG, MEG, CCL and TARC are studied and found excellent for the MIMO antenna implementation. The channel loss of the proposed 4 × 4 MIMO antenna is calculated and found 21.54 b/s/Hz at SNR of 20 dB. The proposed design is modeled in CST Microwave Studio and the results are compared with the fabricated prototype antenna for the practical implementations.

An ultrawideband antenna with two independently tunable notch bands

This paper presents a planar CPW-fed Ultrawideband (UWB) antenna with two independently tunable notch bands. The proposed design consists of a modified Rhombus-shaped monopole structure that is integrated with a dual band-stop filter based on hexagonal split ring resonators (HSRR). The antenna is capable of suppressing multiple frequency bands within ultrawideband range (3.1–11 GHz) such as WLAN and X-band downlink satellite communication frequency bands with an independent tunable mechanism to fulfill the on-demand band rejection. The frequency reconfigurability of the two notch bands is obtained by loading the hexagonal filter arms with two varactor diodes (for each band). Details of antenna design steps and reconfigurability mechanism are illustrated. The notch band element is explained using equivalent circuit model and surface current distribution at lower and higher notch frequency bands. A prototype of the proposed design is printed on the RO4003C (ϵr = 3.55) substrate printed circuit board (PCB) and tested to authenticate the performance. The proposed antenna volume is 21.5 ▪ 48 ▪ 1.524 mm3 and demonstrates an omnidirectional radiation pattern in E and H planes with an average gain of 3.7 dBi across the operational passbands, while a sharp reduction in gain of -6.8 dBi and -3.5 dBi is achieved at the lower and higher notch bands, respectively. Continuous tuning is achieved experimentally from 5.08 to 5.77 GHz and 7.75 to 8.52 GHz for the lower and higher notch bands, respectively. Excellent agreement is observed between the simulated and measured results. Application areas include radio-frequency identifications, ground-penetrating radar, and wireless communications.

Electromagnetic band gap coupled tri‐notched miniaturized ultra‐wideband antenna loaded with slot and parasitic strip

SummaryAn electromagnetic band gap (EBG) coupled miniaturized tri‐notched printed ultra‐wideband (UWB) monopole microstrip antenna having dimensions of 22 mm × 26 mm × 1.6 mm loaded with a slot in radiating patch and a parasitic strip in the ground plane has been presented. The proposed structure incorporates a square‐shaped metallic radiating patch with a square EBG structure adjacent to the microstrip feed line, a U‐shaped meandered slot over the radiating element, and a U‐shaped parasitic resonator at the ground plane beneath the radiating element, to reject the C‐band satellite downlink (3.7 to 4.2 GHz), WLAN frequency band (5.15 to 5.85 GHz), and X‐band satellite downlink (7.25 to 7.75 GHz) frequency bands, respectively. The designed antenna operates in the frequency range from 3 to 11.1 GHz, with an impedance bandwidth of 8.1 GHz and a percentage bandwidth of 114%. Modification steps incorporating into the reference antenna to achieve the desired design objectives have been discussed, along with parametric studies. The proposed design has been simulated using Ansys HFSS, and measurement has been taken using standard measurement technique and compared with the simulated results.

Compact Ultra-­Wideband Planar Inverted F Antenna on Laminated Paper­-Based Substrate with Reduced Specific Absorption Rate

This paper presents a laminated paper-based Planar Inverted F Antenna (PIFA) for wireless body area network (WBAN) applications. The major challenges like providing adequate thickness, uniformity of surface, and water wet ability associated with paper substrate have been transcended in this antenna design by laminating the substrate with a transparent sheet. The simulated and measured reflection coefficients of the fabricated antenna in free space and on human arm are remarkably good, validating the prototype’s utility. It can operate effectively in GSM, WMTS, GPS, DCS, ISM, WiMAX, HIPERLAN, WLAN, and UWB frequency bands with S11 less than -10 dB and the gain ranging from 0.94 to 9.53 dB (free space) and 1.03 to 6.07 dB (on-body). The electrical size of the proposed antenna is 0.16 λg x 0.12 λg at 0.7 GHz with a group delay below 2.3 ns over the desired frequency bands. The performance characteristics are also investigated on-body and it encompasses most of the desired frequency bands for the body area network. This paper also analyses the specific absorption rate (SAR) of the designed antenna by placing it on a tissue-layered human arm model, which is 0.64 Watt/kg, complying with the SAR safety guidelines.

Multifunctional twelve port frequency agile diversity antenna for indoor wireless applications

The recent resurgence of new-generation reconfigurable technologies delivers a plethora of various applications in all public, private and enterprise solutions over the globe. In this paper, a frequency reconfigurable polarization and pattern diverse Multiple-Input-Multiple-Output (MIMO) antenna is presented for indoor scenarios. The MIMO antenna is comprised of twelve radiating elements, and polarization and pattern diversity is obtained by arranging them in three different planes: Horizontal Plane (HP), Vertical Plane-I (VP-I), and Vertical Plane-II (VP-II). The proposed antenna operates in mode I (wideband) and mode II (multiband), by combining two different radiators using PIN diodes. The antenna dynamically switches between Mode I (wideband) and mode II (multiband). Mode, I cover the ultra-wideband (UWB) range from 2.3 to 12 GHz, while mode II covers GSM (1.85–1.9 GHz), Wi-Fi and LTE-7 (2.419–2.96 GHz), 5G (3.15–3.28 GHz and 3.45–3.57 GHz), public safety WLAN (4.817–4.94 GHz), and WLAN (5.11–5.4 GHz) frequency bands. The peak gain and efficiency of the MIMO antenna are 5.2 dBi and 80%, respectively.

A multiband quasi‐Yagi antenna using stepped driver and slotted ground for 2.4/3.5/5.2 GHz bands applications

AbstractA multiband quasi‐Yagi antenna using a stepped driver and slotted ground for the applications of 2.4/3.5/5.2 GHz bands is presented. The ground plane modifications match impedance and help form the resonances, while the stepped driver parameters allow independent control of resonance frequencies. The antenna shows multiband characteristics and has achieved dB in three different frequency bands of 2.15–2.65, 3.4–4, and 5–5.3 GHz. Furthermore, the antenna shows a stable gain of around 3.9–4.9 dBi and retains its general radiation characteristics for all frequency bands. The simulation and measurement results agree well with each other. The proposed antenna is suitable for applications requiring general quasi‐Yagi antenna characteristics for wireless communications applications for WLAN, WiMAX, ISM, and Bluetooth frequency bands.

A super wideband MIMO antenna with metamaterial superstrate for gain enhancement at WLAN frequency band

A super wideband MIMO antenna with metamaterial superstrate for gain enhancement at WLAN frequency band

Design and performance analysis of a compact, wideband dual polarized antenna for WLAN & WiMAX applications

Abstract Dual polarization is achieved by putting a rectangular or circular patch in between two orthogonal gaps. At the beginning a single-polarized patch is considered. Then by using anequivalent circuit, the impedance matching property of the gap is being configured. After optimization of the length of the patch and width of the gap, a dual polarized antenna is being considered. Here in this article we projected a new technique to design dual polarized microstrip antenna for WLAN, WiMAX, wireless applications using circular patch. By combining all resonant modes we have finally achieved a wide operating bandwidth. Experimental result of the projected antenna shows the operating bandwidth of 21.56% (5.24–6.37 GHz) for (differential mode S-parameter) S dd11 ≤ −10 dB with a high port isolation of 40 dB and a relative gain of 13.5 dBi is achieved. From the result analysis this antenna finds its applications for various WLAN and Wi-MAX frequency band.

Design and Performance Analysis of a Compact Planar MIMO Antenna for IoT Applications.

This article presents a quad-band multiple-input-multiple-output (MIMO) antenna for the Internet of Things (IoT) applications. The proposed antenna consists of four quarter-wavelength asymmetrical meandered radiators, microstrip feed lines, and modified ground planes. The antenna elements are arranged in a chiral pattern to improve isolation between them, with two radiators and two ground planes placed on the front side of the substrate and the other two on the back side. The MIMO antenna has an operating bandwidth (S11 ≤ −10 dB) of 1.76–1.84 GHz, 2.37–2.56 GHz, 3.23–3.68 GHz, and 5.34–5.84 GHz, covering GSM, WLAN, WiMAX, and 5G frequency bands. The isolation between the radiating elements is greater than 18 dB in the operating bands. The peak gain of the antenna is 3.6 dBi, and the envelope correlation coefficient (ECC) is less than 0.04. Furthermore, the proposed antenna is validated for IoT-based smart home (SH) applications. The prototype MIMO antenna is integrated with a commercially available ZigBee device, and the measured values are found to be consistent with the expected results. The proposed MIMO antenna could be a good candidate for IoT systems/modules due to its low profile, compact size, lightweight, and easy integration with wireless communication devices.

A Broadband Circularly Polarized Antenna with Low-Profile and Wide Axial Ratio Beamwidth

In this work, the design and the characterization of a broadband circular polarized monopole having low-profile and wide axial ratio beamwidth were presented. The antenna was designed on readily available, inexpensive glass-reinforced epoxy substrate having an overall size of 0.56λ0×0.50λ0×0.029λ0 (at center frequency 5.5 GHz). The proposed antenna was a modification of a square-shaped monopole antenna, which incorporates a pair of peripheral slits and an off-center slot for a elliptical polarized radiation. A v-shaped notch below the feed line was introduced and extended as antenna ground to generate broadband circular polarization characteristics. The −10 dB reflection coefficient bandwidth and 3-dB axial-ratio bandwidth of the proposed antenna were measured to be of 47.6 and 27 %, respectively. The 3-dB axial ratio beamwidth of the antenna was 93.5°. The antenna proposed in this work covers multiple application frequency bands including HiperLAN/2 IEEE 802.11a (5.15 - 5.35 GHz / 5.47 - 5.725 GHz) band, WLAN frequency band (5.1 - 5.9 GHz), C-band uplink (5.925 - 6.325 GHz) and part of military application band (4.75 - 4.99 GHz). HIGHLIGHTS Design and characterization of a broadband circular polarized monopole having low-profile and wide axial ratio beamwidth Proposed antenna covers multiple application frequency bands including HiperLAN/2 IEEE 802.11a, WLAN, C-band uplink and part of military application bands Proposed antenna is compact, low-profile and exhibits good polarization purity GRAPHICAL ABSTRACT

A Multiband Antenna Stacked with Novel Metamaterial SCSRR and CSSRR for WiMAX/WLAN Applications.

This paper presents an innovative method for the design of a triple band meta-mode antenna. This unique design of antenna finds application in a particular frequency band of WLAN and WiMAX. This antenna comprises of a square complimentary split ring resonator (SCSRR), a coaxial feed, and two symmetrical comb shaped split ring resonators (CSSRR). The metamaterial unit cell SCSRR independently gains control in the band range 3.15–3.25 GHz (WiMAX), whereas two symmetrical CSSRR unit cell controls the band in the ranges 3.91–4.01 GHz and 5.79–5.94 GHz (WLAN). This design methodology and the study of the suggested unit cells structure are reviewed in classical waveguide medium theory. The antenna has a miniaturized size of only 0.213 × 0.192 × 0.0271 (20 × 18 × 2.54 mm3, where is the free space wavelength at 3.2 GHz). The detailed dimension analysis of the proposed antenna and its radiation efficiency are also presented in this paper. All the necessary simulations are carried out in High Frequency Structure Simulator (HFSS) 13.0 tool.

Low-SAR Antenna Design and Implementation for Mobile Phone Applications

This paper presents a novel approach for designing low-SAR (specific absorption rate) terminal antenna. First of all, the relationship between the magnetic field and the SAR value is deduced by using the electric field formula of SAR and Maxwell's equations. Then, by using the boundary conditions of the medium, the interaction mechanism between the radiated magnetic field of the antenna and the magnetic field inside human tissue is studied. Next, the relationship between the surface current and the radiated magnetic field of antenna is constructed. The approach of reducing the antenna radiated magnetic field is proposed by directly adjusting the antenna surface current, so that the SAR of human tissues is reduced. Finally, two low-SAR antennas are designed according to the proposed approach. The simulation and measurement results of the two low-SAR antennas show that the -6 dB bandwidth of both antennas is 2.4-2.49 GHz, which can meet the 2.4 G WLAN frequency band. At the same time, compared with the reference antenna, the peak values of 10 g average SAR of two antennas are reduced by more than 30%. In addition, the measured efficiencies of the two low-SAR antennas are higher than 40% in the operating frequency range. The validity of the proposed approach is proved by the simulation and measurement results of the antenna, which can be used to guide the SAR reduction design of mobile terminal antennas.

Electronically Reconfigurable WLAN Band-Notched MIMO Antenna for Ultra-wideband Applications

A low-profile electronically reconfigurable WLAN band-notched dual port multiple-input multipleoutput (MIMO) antenna design for ultra-wideband applications has been presented. Antenna elements exhibit good impedance match (S11 ≤ -10 dB) over entire ultrawideband (3.1 to 10.6 GHz) spectrum. The decoupling structure is used to improve isolation (S12/S21) above 20 dB over entire UWB band. Moreover, reconfigurable band-notching is achieved by inserting PIN diodes along the inverted L-shaped slots, in each radiator. Notch at WLAN (5.5 GHz) frequency band is achieved by switching the PIN diode to ‘OFF’ state. The antenna design is fabricated as well as measured, and the results suggests that the proposed design with switchable WLAN band-notch characteristics is suitable candidate for ultra-wideband applications.

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.

Wearable Tri-Band Antenna for Switching Between WLAN and Bluetooth for Body Centric Wireless Communication

This paper presents a novel, flexible, and compact tri-band switchable antenna for body-centric wireless communication. The proposed antenna possesses the capability to switch between Bluetooth and WLAN frequency band by utilizing a single switch without affecting other operating passbands. The antenna is designed on a flexible substrate having an optimized size of 50 × 55 mm2. The proposed antenna design demonstrates advantageous radiation patterns with S11 < − 10 dB in passbands of both states. Moreover, measured and simulated results in both states exhibit good agreement. Based on the developed results, this antenna proves to be an appropriate choice for various wireless applications including WLAN, Bluetooth, WiMAX, and X-band satellite communication systems. Moreover, it is also shown by simulations that the proposed antenna is suitable for on-body communications.