GHz Wireless Local Area Network Bands Research Articles

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.

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).

A compact four-band high-isolation quad-port MIMO antenna for 5G and WLAN applications

A miniaturized quad-port multiple-input-multiple-output (MIMO) antenna, generating four-band and high port isolation properties, is developed for 5G and wireless local area network (WLAN) applications. The realized MIMO antenna consists of four elements. Each element combines multiple L-shaped and rectangular branches with concave grounds, so that good impedance matching in four frequency bands is reached. The four elements are orthogonally placed to reduce current coupling. Moreover, four pairs of rotationally symmetrical strip lines are added to further improve the isolation between the units at low frequency. The antenna has been optimized to achieve a compact size of 39 mm × 39 mm × 1.6 mm, covering three 5G bands (2.6/3.5/4.8 GHz) and the 5.8 GHz WLAN band. In addition, inter-port isolation is better than 21.5 dB. Furthermore, the measured envelop correlation coefficient is smaller than 0.012 in the desired bands. Measurements also show that the radiation patterns and gains of the fabricated antenna agree well with the simulated ones. The diversity gain is as good as 9.94 dB. Moreover, the channel capacity loss is satisfactory, being below 0.4 bits/s/Hz. Satisfactory efficiency and diversity performance are realized. These facts indicate that the antenna system is a promising candidate for MIMO usage on 5G and WLAN devices.

Inkjet Printed Metamaterial Loaded Antenna for WLAN/WiMAX Applications

In this paper, the design and performance analysis of an Inkjet-printed metamaterial loaded monopole antenna is presented for wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) applications. The proposed metamaterial structure consists of two layers, one is rectangular tuning fork-shaped antenna, and another layer is an inkjet-printed metamaterial superstate. The metamaterial layer is designed using four split-ring resonators (SRR) with an H-shaped inner structure to achieve negative-index metamaterial properties. The metamaterial structure is fabricated on low-cost photo paper substrate material using a conductive ink-based inkjet printing technique, which achieved dual negative refractive index bands of 2.25–4.25 GHz and 4.3–4.6 GHz. The antenna is designed using a rectangular tuning fork structure to operate at WLAN and WiMAX bands. The antenna is printed on 30 × 39 × 1.27 mm3 Rogers RO3010 substrate, which shows wide impedance bandwidth of 0.75 GHz (2.2 to 2.95 GHz) with 2 dB realized gain at 2.4 GHz. After integrating metamaterial structure, the impedance bandwidth becomes 1.25 GHz (2.33 to 3.58 GHz) with 2.6 dB realized gain at 2.4 GHz. The antenna bandwidth and gain have been increased using developed quad SRR based metasurface by 500 MHz and 0.6 dBi respectively. Moreover, the proposed quad SRR loaded antenna can be used for 2.4 GHz WLAN bands and 2.5 GHz WiMAX applications. The contribution of this work is to develop a cost-effective inject printed metamaterial to enhance the impedance bandwidth and realized the gain of a WLAN/WiMAX antenna.

An in‐band full‐duplex antenna for dual‐band application

AbstractA dual‐band, dual‐polarized in‐band full‐duplex antenna with good isolation performance is presented for wireless local area network (WLAN) applications. A neutralization line is connected between the grounds of the transmitter (Tx) and receiver (Rx) antennas to enhance the isolation. Further enhancement in isolation is achieved by using a 180° ring hybrid coupler between receiving antenna elements. Here the dual‐band monopole antennas are used as transmitting and receiving antenna elements. For better isolation, the receiving antenna elements are placed opposite to each other and fed through the differential ports of the 180° ring hybrid coupler. The proposed structure is fabricated, and the comparison of measured results and simulated results are studied. The simulated and measured impedance bandwidths (≤−10 dB) of the antenna cover the entire 2.4 GHz WLAN band (2.4–2.48 GHz), and for this band, the measured isolation is better than 40 dB. For the higher band, the measured isolation is more than 40 dB for 200 MHz (5.15–5.35 GHz) of bandwidth. The simulated radiation patterns of the antenna are well‐matched with the measured patterns at both the frequencies.

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.

Integrated Four Low-Profile Shorted Patch Dual-Band WLAN MIMO Antennas for Mobile Device Applications

Four dual-band shorted patch antennas (SPAs) with a low profile of 1 mm ( $0.008\lambda $ at 2.4 GHz) integrated into a square-ring structure of size 66 mm $\times66$ mm (about 0.53 $\lambda \times 0.53\lambda $ at 2.4 GHz) for 4 $\times {4}$ multiinput-multioutput (MIMO) operation are presented for mobile device applications. Each SPA consists of a larger shorted patch and a smaller shorted patch to, respectively, generate the 2.4 GHz band (2400–2484 MHz) and 5.8 GHz band (5725–5875 MHz) for dual-band wireless local area network (WLAN) operation. Two SPAs are orthogonally connected with the first SPA’s larger shorted patch and the second SPA’s smaller shorted patch sharing a common metal wall at the corner of the square-ring structure. By repetitively connecting the third SPA to the second one and finally the fourth SPA to the third and first ones, the proposed design can generate four decoupled waves in the 2.4 GHz/5.8 GHz WLAN bands with very low envelope correlation coefficients of less than 0.1. With 1 mm low profile, the proposed WLAN MIMO antennas are expected to find applications in integration with the back cover of the mobile device.

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.

Design and Fabrication of DGS Microstrip Patch Antenna for S, C &amp; X Band Applications

The design and simulation of defected ground structure microstrip patch antenna for Worldwide Interoperability for Microwave Access (WiMAX) and Wireless Local Area Network (WLAN) applications are additionally testing as the antenna ought to be little in size, light in weight, easy to manufacture, minimal effort, and simplicity of joining in such gadgets. The target of this work is to plan and creation of an antenna which will be appropriate for WiMAX and WLAN applications with improved gain and optimized bandwidth. WiMAX depend on gauges, for example, IEEE 802.16, intended to work between 2-11 GHz and spreads S, C and X microwave recurrence groups. Metropolitan Area Network (MAN) conventions are in the 2.3 GHz, 2.5 GHz, 3.5 GHz and 5.8 GHz ranges. A planar antenna with imperfect ground plane is proposed and manufactured, 3.5/5.5 GHz WiMAX band, 5.2/5.8 GHz WLAN band, 4/6 GHz satellite correspondence, and different remote correspondence applications. This structure canvassed two groups in which it is extending from 3.34-8.72 GHz implies a band of 5.38 GHz with impedance BW 89.22%. The resonating frequencies are 3.92 GHz and 7.88 GHz with return loss - 35.59 dB and - 31.99 dB, VSWR 1.03 and 1.05 and gain 9.46 dB and 0.14 dB respectively. The second band covers 9.22-13.06 GHz implies a band of 3.84 GHz with impedance BW 34.47%. This resounds at 10.58 GHz with return loss - 55.52 dB, VSWR 1.00 and gain is 7.09 dB. The deliberate outcomes are in great concurrence with reproduced consequences of the proposed antenna.

Low-profile WLAN MIMO PIFA Antenna System for Laptops with Large Screen

This paper proposes a low-profile two-element wireless local-area network (WLAN) multi-input multi-output (MIMO) antenna system designed for laptops. The primary and secondary elements are mirror-imaged 3-D metal-plate-loaded planar inverted-F antennas (PIFAs), each measuring only 31 mm × 2 mm × 2 mm. Although structurally simple, each PIFA can generate low- and high-frequency resonant modes through its long- and short-branches, respectively. In addition, the meander shorting metal section can easily be adjusted to shift the resonant frequency and to improve the impedance matching. Without any additional matching circuit or chip components, the antenna can cover the 2.4/5.2/5.8 GHz WLAN bands with a profile height of only 2 mm, which is smaller than the record low in the literature. Moreover, with the two PIFA elements deployed on the left and right sides of the top edge of the display ground plate, the measured isolation is larger than 23 dB in the low-frequency (high-frequency) band, and the measured realized radiation efficiency is at least 52% within all operating bands.

Slim dual‐polarised antenna with omnidirectional patterns for WLAN applications

A slim dual-polarised antenna with omnidirectional patterns is proposed for wireless local area network (WLAN) applications. The antenna is a composition of a modified J-type antenna for vertical polarisation and two crossed-loop antennas for horizontal polarisation. For improving the isolation between the two polarisations, a rectangular loop is partially added in the middle of one of the loop antenna, connecting the end of the J-type antenna. The rectangular loop also acts as tuning the impedance of the antenna. For achieving omnidirectional patterns of the horizontal polarisation, a series circular feeding network is designed to excite the loop antennas. The antenna is fabricated by copper and the circular network is printed on a substrate. Measurement results show the 10 dB return losses of the two ports are covering the whole 2.4 GHz WLAN band, with the isolation better than 20 dB. The gains vary <2.2 dB in the horizontal plane for both the polarisations. With the advantages of slim structure, lightweight, and easy fabrication, the proposed antenna is convenient to use in the WLAN routers.

The design of the dual band folded dipole antenna with a parabolic curved reflector

AbstractThis article proposed a dual band dipole antenna with a curved reflector that can be used in the wireless local area network (WLAN). The shape of the proposed antenna is similar to quasi‐yagi antenna as it combines the dipole antenna with folded dipole.When designing the antenna with a reflector using the standard antenna reflector uses a 2.45 GHz band, and the size of the band used here was relatively large at 5.5 GHz. As a result, a null occurred in the main lobe of the radiation pattern at the 5.5 GHz band, which ultimately reduced the gain. To solve this problem, a parabolic curved reflector was applied in this study. The designed antenna satisfied the condition of return loss smaller than −10 dB at the 2.45 GHz and 5.5 GHz WLAN bands. The gain of the antenna was larger than 8 dBi at 2.45 GHz and at 5.5 GHz.

Compact, Printed, Tri-Band Loop Antenna With Capacitively-Driven Feed and End-Loaded Inductor for Notebook Computer Applications

The shorted monopoles and the planar inverted-F antennas have been utilized for wireless local area network (WLAN) notebook applications for years. This paper presents an alternative and yet promising antenna type with a compact and smaller size of 5 mm $\times20$ mm to operate in the 2.4 GHz (2400–2484 MHz), 5.2 GHz (5150–5350 MHz), and 5.8 GHz (5725–5825 MHz) WLAN bands. The loop antenna, formed on a 0.4-mm-thick FR4 substrate, was adopted in this study. The loop radiator comprised a capacitively-driven feed and an end-loaded inductor. The capacitively-driven feed allowed the antenna to generate the quarter-wavelength loop resonance for possible lowest resonant mode excitation in addition to the loop’s half-wavelength mode. By loading an inductor at the loop end to be connected to the small antenna ground, the operating frequencies of the quarter- and half-wavelength resonances were further decreased to cover the 2.4 and 5.2/5.8 GHz bands with good input impedance therein.

Design and Modeling of a Compact Reconfigurable Slot Antenna for WLAN Portable Devices

This paper presents design and modeling of acompact reconfigurable quarter wavelength slot antennacompatible with the portable devices of the 5GHz wireless localarea network (WLAN) applications. The concept of thetransverse resonant method which is used for the transmissionlines is utilized for modeling the proposed slot antenna. A PINdiode is used to switch the antenna operating band from thelower unlicensed indoor 5GHz WLAN band (5-5.3) GHz to theupper one (5.7-5.9) GHz and vice versa. Another PIN diode isattached to the feed line to provide suitable matching stublength for each operation mode. Furthermore, the shape of theradiating slot of the proposed antenna is modified to providean omnidirectional radiation pattern in the H-plane suitablefor the portable gadgets of the WLAN system. Themeasurements are in well agreement with the simulatedresults, and they verify the precision of the suggested modeland the enhanced matching characteristics for the twooperation modes of the proposed antenna

Isolation enhancement of small-size WLAN MIMO antenna array for laptop computer application

This paper proposes a multiple-input multiple-output (MIMO) antenna array comprising two compact wireless local-area network (WLAN) antennas with high isolation in between. The two operating frequency bands are designed to completely enclose the 2.4/5.2/5.8 GHz WLAN bands. The MIMO antenna array having a small size, a low height, and a small thickness is especially suitable to be installed in ultra-thin notebook computers. The size of the designed antenna array has been reduced to about 40% than those of the MIMO arrays appearing in the recent literature. The designed isolation element between the two radiating antennas consists of two resonant slots, the lengths of which are individually a quarter-wavelength at 2.45 and 5.5 GHz. The isolation elements block the horizontal surface currents on the system ground plane, leading to mutualcoupling reduction between the two source antennas and hence excellent isolation between them. Results indicate that the proposed MIMO antenna array has good characteristics of antenna radiation efficiency, and impedance matching in the two bands of interest.

Switchable Long-Term Evolution/ Wireless Wide Area Network/ Wireless Local Area Network Multiple-Input and Multiple-Output Antenna System for Laptop Computers

This paper introduces a multiple-input and multiple-output (MIMO) antenna system for deployment in the closed hinge slot region of notebook computers for long-term evolution (LTE)/wireless wide area network (WWAN)/wireless local area network (WLAN) applications. This antenna system was placed in the closed hinge slot region formed by the full metal cover, metal ground plate, and metal hinges. The MIMO antenna system, includes a main antenna (Ant 1), an auxiliary antenna (Ant 2), and an isolation element. The main and auxiliary antennas were integrated with the metal surrounding them and were used to excite several resonance modes of the closed hinge slot. Excellent antenna efficiency was achieved using the small antennas. Although Ant1 and Ant2 are only 25 mm $\times5$ mm in size, they could cover LTE/WWAN or WLAN operating bands by switching feed points in the same antenna pattern. The isolation element—a 10 mm $\times6$ mm metal sheet—was placed at the center of the closed hinge slot region, and enhanced isolation by more than 7 dB. The isolation levels exceeded 18 dB for LTE700/2300/2500 bands and 15 dB for 2.4/5.2/5.8 GHz WLAN bands.

Digital FMCW for ultrawideband spectrum sensing

AbstractAn ultrawideband digital frequency‐modulated continuous wave sensing engine is proposed as an alternative technique for cognitive radio applications. A dual‐band demonstrator capable of sensing 750 MHz bandwidth in 204.8 µs is presented. Its performance is illustrated from both bench tests and from real‐time measurements of the GSM 900 band and the 2.4 GHz wireless local area network (WLAN) band. The measured sensitivity and noise figure values are −90 dBm for a signal‐to‐noise ratio margin of at least 10 dB and ~13–14 dB, respectively. Data were collected over 24 h and were analyzed by using the energy detection method. The obtained results show the time variability of occupancy, and considerable sections of the spectrum are unoccupied. In addition, unlike the cyclic temporal variations of spectrum occupancy in the GSM 900 band, the detected variations in the 2.4 GHz WLAN band have an impulsive nature.

Penta‐band circularly polarised antenna using a lumped capacitor

A very simple printed monopole antenna with penta-band circularly polarised (CP) radiation characteristics for wireless local area network (WLAN), worldwide interoperability for microwave access, and downlink of the X-band satellite communication applications is proposed for the first time. The antenna comprises a notched rectangular ground plane and a radiating patch consisting of inverted-U-shaped, I-shaped, and inverted-L-shaped radiators, and creates four CP modes operating at 2.4/3.5/5.8/7.5 GHz frequency bands. By placing a lumped capacitor of 0.5 pF in the gap between the I-shaped radiator and the inverted-L-shaped radiator, an extra CP mode at 5.2 GHz WLAN band is generated, thus completing the penta-band CP antenna. The measured −10 dB impedance bandwidth of the demonstrated antenna is 340 MHz (2.37–2.71 GHz) and 4.8 GHz (3.2–8 GHz), and the measured 3 dB axial-ratio bandwidth is 16.6, 13.5, 2.9, 2.4, and 4% in five distinct bands of 2.1−2.48, 3.1−3.55, 5.1−5.25, 5.76−5.9, and 7.45−7.75 GHz.

The design of a dual band omnidirectional horizontally polarized antenna with arc‐shaped lines and overlapping lines

ABSTRACTThis article proposes a dual‐band horizontally polarized omnidirectional antenna for wireless local area network (WLAN) applications. Typically, multiple elements with different sizes have been combined to create antennas that operate in two separate bands. Unlike such previous attempts, the proposed antenna achieves dual band operations by modifying the form of the feed line. The proposed antenna has a similar structure as the Alford loop antenna, but the existing straight feed lines of the Alford loop antenna are modified to arc‐shaped lines. The arc‐shaped feed lines are then attached to the antenna elements in four different directions. The voltage standing wave ratio (VSWR) of the proposed antenna is &lt;2:1 at the 2.4 (2.4–2.48) and 5 (5.15–5.825) GHz WLAN bands. The gain of the proposed antenna is above 0 dBi at the two bands. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1117–1121, 2016

Low-Profile Repeater Antenna with Parasitic Elements for On-On-Off WBAN Applications

A low-profile repeater antenna with parasitic elements for on-on-off WBAN applications is proposed. The proposed antenna consists of a planar inverted-F antenna (PIFA), two parasitic elements, and a ground plane with a slot. Due to the slot, the impedance matching of the resonance formed by the PIFA is improved, which makes the proposed antenna operate in the 5.8 GHz industrial, scientific, and medical (ISM) band. To cover the 5.2 GHz wireless local area network (WLAN) band, a dual resonance characteristic is realized by the slot and the two parasitic elements. The first coupling between the PIFA and the slot not only makes the slot operate as a resonator, but also forms secondary coupling between the slot and the two parasitic elements. The two parasitic elements operate as an additional resonator due to secondary coupling. The antenna has the enhanced near surface radiation in the 5.8 GHz ISM band due to addition of the slot and radiation toward off-body direction in the 5.2 GHz WLAN band. In order to evaluate antenna performance considering the human body effect, the antenna characteristics on a human equivalent phantom are analyzed.