Dual-band Wireless Local Area Network Research Articles

Design and Geometric Transformations of Koch Curve Monopole Antennas

In this paper, a modified Koch curve monopole antenna is proposed for the dual-band Wireless Local Area Network (WLAN) and its performance has been compared with the conventional printed Koch-curve monopole antenna. Both the antennas have been contrived, and their simulated return loss and radiation pattern results have been validated with the measurements. Antenna #1 is designed on the geometrical basis of a conventional Koch-curve monopole antenna. Moreover, the shape of antenna # 1 is bent with a two-step rotation process to yield antenna #2. There are two advantages to this geometrical modification: Firstly, the unique rotation in antenna #2 has further increased the mutual coupling between the segments of the Koch-curve geometry, and thus improved the impedance matching. Secondly, due to its geometric configuration that enhanced its ground plane size, the proposed antenna #2 has been able to demonstrate consistent simulation and measurement results. The compact ground plane in antenna #1 has been identified as the primary reason for the disagreement between the simulated and measured return loss results. The presented antennas have also been studied for the variation of indentation angles: θ=30 and θ=60.

Dual-Band Circularly Polarized Omni-Directional Biconical Antenna With Double-Circular Parallelepiped Elements for WLAN Applications

This research proposes a novel dual-band (2.45/5.80 GHz) omnidirectional circularly polarized (CP) biconical antenna with double-circular parasitic parallelepiped elements for wireless local area network (WLAN) applications. The proposed dual-band CP antenna scheme consisted of a biconical radiating structure surrounded by inner- and outer-circular parallelepiped elements that convert linearly polarized electric fields into CP fields. Simulations were performed to optimize the antenna parameters, and an antenna prototype was fabricated and experiments were conducted. The measured impedance bandwidths (IBWs) were 44.4% (1.84 – 2.89 GHz) and 4.56% (5.73 – 5.99 GHz) for the lower- (2.4 GHz) and upper-frequency (5.80 GHz) bands, respectively. The corresponding 3-dB axial ratio bandwidths (ARBWs) were 11.22% (2.27 – 2.54 GHz) and 10.49% (5.6 – 6.2 GHz). The radiation patterns of the dual-band antenna scheme were omnidirectional left-hand circular polarization, with the measured antenna gains of 3.2 dBic and 8.5 dBic at 2.45 and 5.80 GHz, respectively. The simulated and measured results were reasonably agreeable. Despite the narrow IBW and ARBW for the upper-frequency band, the bandwidths adequately covered the target upper frequency band, rendering the proposed CP omnidirectional biconical antenna scheme operationally suitable for WLAN applications. Furthermore, the novelty of this research lies in the use of a biconical radiating structure augmented with double-circular parasitic parallelepiped elements to realize circular polarization for dual-band WLAN applications.

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

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

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.

Miniaturized Dual-Band FSS Suitable for Curved Surface Application

Based on a single metallic layer printed circuit board (PCB), a miniaturized dual-band frequency selective surface (FSS) is proposed that could fulfill thin substrate design for curved application and provide stable resonant frequency. Due to the property that the element size can be altered by using different thicknesses of substrate, the FSS could either be designed for the compact size or in a very thin substrate. Two practical designs for dual-band wireless local area network (WLAN) are demonstrated featuring a flexible and straightforward design method. The compact one has an element size of only 5.2% of the free space wavelength at the lower resonant frequency, which is the smallest dual-band WLAN FSS by using only one metallic layer in published literature. Another thin substrate design (0.4 mm PCB) is fabricated and measured to confirm that the FSS exhibits stable resonant frequency on curved surfaces with different curvatures. The measured frequency shift is only 2.2%, which is among the smallest percentage in the literature.

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.

Very-Low-Profile Grounded Coplanar Waveguide-Fed Dual-Band WLAN Slot Antenna for On-Body Antenna Application

A very-low-profile grounded coplanar waveguide (GCPW)-fed slot antenna with an antenna thickness of 0.8 mm (about 0.0064λ at 2.4 GHz) and a compact size of 15 mm × 40 mm (about 0.12λ × 0.32λ at 2400 MHz) for 2.4/5.8 GHz dual-band wireless local area network on-body antenna application is presented. The GCPW slot antenna consists of a top ground with the GCPW feedline and radiating slot embedded thereon and a bottom ground spaced 0.8 mm to the top ground. The radiating slot is an asymmetric T-shaped slot having a longer slot path for 2400~2500 MHz band and a shorter slot path for 5725~5875 MHz band. It is convenient to tune the dual-band operation by adjusting the lengths of the longer and shorter slot paths, respectively. Additionally, owing to the presence of the bottom ground, the GCPW slot antenna has decreased backward radiation. This causes the antenna's impedance matching to be very slightly varied when it is in the proximity of a human body.

Isolation and frequency reconfigurable compact MIMO antenna for wireless local area network applications

In this study, to design a compact four-port multiple-input-multiple-output (MIMO) antenna for dual-band wireless local area network applications, both frequency and isolation between antennas are made as reconfigurable. Both antenna element and decoupling network shown in this study are designed using meander line concept. The frequency reconfigurable capability of the antenna is achieved by incorporating positive-intrinsic-negative (PIN) diodes in the meander line resonator. By making PIN diodes ON and OFF, four antenna elements switch their operating frequency in between 2.4-2.5 and 5.1-5.8 GHz bands. Isolation between the antenna elements also made as reconfigurable by placing PIN diodes in the decoupling network. In ON state, isolation is found in 2.4-2.5 GHz band, whereas in OFF state, isolation is achieved in 5.1-5.8 GHz band. Overall, in both the bands, excellent isolation (more than 15 dB) between the antenna elements has been achieved. The proposed antenna design is printed on the FR-4 substrate and its overall area is 38 × 38 mm 2 . Each antenna element is in polarisation diversity with the adjacent antenna element which makes the proposed design suitable for achieving good MIMO performance.

Wearable Button Antenna for Dual-Band WLAN Applications With Combined on and off-Body Radiation Patterns

A new type of wearable button antenna for wireless local area network (WLAN) applications is proposed. The antenna is composed of a button with a diameter of circa 16 mm incorporating a patch on top of a dielectric disc. The button is located on top of a textile substrate and a conductive textile ground that are to be incorporated in clothing. The main characteristic feature of this antenna is that it shows two different types of radiation patterns, a monopole type pattern in the 2.4 GHz band for on-body communications and a broadside type pattern in the 5 GHz band for off-body communications. A very high efficiency of about 90% is obtained, which is much higher than similar full textile solutions in the literature. A prototype has been fabricated and measured. The effect of several real-life situations such as a tilted button and bending of the textile ground have been studied. Measurements agree very well with simulations.

Dual-Band Antenna Integrating With Rectangular Mushroom-Like Superstrate for WLAN Applications

A rectangular mushroom-like superstrate structure is proposed to design an antenna for dual-band wireless local area network (WLAN) applications. The proposed antenna consists of an array of mushroom-like rectangular patches and a planar slot antenna. Based on the dispersion diagram analysis, the proposed antenna can operate in two bands: The lower band is from 2.3 to 2.98 GHz, with -10-dB bandwidth of 25.8%, which is corresponding to zeroth-order resonant (ZOR) mode, and the upper band is from 5.02 to 5.84 GHz, with -10-dB bandwidth of 15.1% and average realized gain of 6.9 dB at boresight. The proposed antenna is feasible to cover the specification for dual-band WLAN applications in the 2.4-GHz (2400-2484 MHz) and 5-GHz (5150-5825 MHz) bands. Furthermore, the proposed antenna has a low profile of 4.2 mm and compact size of 33 ×30 mm 2 , which is suitable for installation in wireless handheld devices. The simulated and measured results are in good agreement to verify the good performance of the proposed antenna.

Compact slot antenna for wireless local area network 2.4/5.2/5.8 GHz applications

This investigation presents a compact (30 × 30 mm 2 ) microstrip-fed slot antenna design for dualband wireless local area network (2.4 / 5.2 / 5.8 GHz) applications. Two dissimilar inverted L-shaped slots and a mushroom-shaped slot were loaded into the antenna. By feeding these slots with a microstrip-fed line that was analogous to a sling hook, three resonant modes were excited at exactly 2.44, 5.25 and 5.8 GHz, which formed lower and upper operating bands with 10 dB bandwidths of 5.67 and 25.14%, respectively. The process of designing the proposed antenna is explicitly shown, and parametric studies were carried out by simulation. Typical experimental measurements were also conducted and compared with the simulated results.

Requirements Analysis of Dual Band MIMO Antenna

A compact CPWfed double T-shaped antenna with multiple layer dielectric substrates is proposed for dual-band Wireless Local Area Network (WLAN) operations. For the proposed antenna, the $$-$$-10 dB return loss bandwidth could reach about $$28.57\,\%$$28.57% for the $$2.45$$2.45 GHz band and $$6.15\,\,\%$$6.15% for the $$5.2$$5.2 GHz band which meet the required bandwidth specification of WLAN standard. To get high isolation and improve the performances of the Multiple-Input---Multiple-Output (MIMO) systems, we suggested using the novel Left Handed Metamaterial with multiple bands called M-band Nested U-Ring Resonator after fractional removal of substrate. An evaluation of MIMO antennas is presented, with analysis of the mutual coupling, correlation coefficient, diversity gain and correlation efficiency. As per results, the proposed solution meets the requirements for practical WLAN applications.

A CPW-Fed Rectangular Ring Monopole Antenna for WLAN Applications

We present a simple coplanar waveguide- (CPW-) fed rectangular ring monopole antenna designed for dual-band wireless local area network (WLAN) applications. The antenna is based on a simple structure composed of a CPW feed line and a rectangular ring. Dual-band WLAN operation can be achieved by controlling the distance between the rectangular ring and the ground plane of the CPW feed line, as well as the horizontal vertical lengths of the rectangular ring. Simulated and measured data show that the antenna has a compact size of21.4×59.4 mm2, an impedance bandwidths of 2.21–2.70 GHz and 5.04–6.03 GHz, and a reflection coefficient of less than −10 dB. The antenna also exhibits an almost omnidirectional radiation pattern. This simple compact antenna with favorable frequency characteristics therefore is attractive for applications in dual-band WLAN.

A New Design of Dual Band Phase Shifter using MEMS Technology

Abstract - This paper presents a new design of microwave microelectromechanical systems (MEMS) phase shifter for dual band wireless local area network (WLAN) applications. A bit is designed which product a constant phase shift of 11.25° by switching between two line that consist of 12 and 6 unitcells in each frequency band. A unitcell is constructed by gold membrane suspended over the coplanar waveguide (CPW) that can be moved vertically by electrostatic actuation which can ultimately be used for changing the operating frequency band. Two states of unitcell are used to switch between two frequency bands of 2.4 GHz and 5.2 GHz (IEEE 802.11 standard employed in dual band WLAN systems). First, a closed form equation of simplified model of structure is obtained. Then using this equation and advanced design system (ADS) simulator, the dual band phase shifter is designed. The validation of modeling and equations are demonstrated using the High Frequency Structure Simulator (HFSS). At the frequency of 2.4 GHz, maximum return and insertion losses are -16.96 and -0.12 dB, respectively that exhibit a phase shift efficiency of 93.75 °/dB (60.22 °/cm). At the frequency of 5.2 GHz, maximum return and insertion loss are -16.86 and -0.15 dB, respectively exhibiting a phase shift efficiency of 75 °/dB (60.22 °/cm). The new proposed design is only to achieve a dual band phase shifter using MEMS technology which has low loss and weight with high linearity respect to the other technologies.

A Hybrid of T-Dipole and Quasi-Yagi Antenna for Dual-band WLAN Access Point

In this paper, a hybrid of T-dipole and quasi-Yagi antenna is presented for using in dual-band Wireless Local Area Network (WLAN) access point. The antenna is made up of combination of T-dipole and quasi-Yagi antenna structures, which are distinctly designed to operate at 2.4 and 5.5 GHz frequency bands. A simply integrated balun that consists of a curved microstrip line and a circular slot to allow broadband characteristic is used to feed the antenna. The final antenna design presents measured bandwidths (RL ≤ − 10 dB) of 2.35 – 2.55 GHz and 4.30 – 6.56 GHz which cover completely the two bands of WLAN. Simulated and measured results of peak gain and radiation patterns in both E- and H-plane validate potential of the design.

Miniaturized Dual-Band Wireless Local Area Network Antenna Using Low-Temperature Co-Fired Ceramic Technology

Absract A very compact wireless local area network antenna using meander striplines in three low-temperature co-fired ceramic layers is designed and fabricated in this study. This chip antenna has a small volume of only 3.2 × 1.6 × 2 mm3. The measured radiation bandwidths (voltage standing wave ratio ≤ 2) of 2.45 and 5.8 GHz are 110 and 150 MHz, and the peak gains of the two bands are −1.6 and 2.7 dBi, respectively. The resonant frequencies can easily be tuned by adjusting the inner coupling between different patterns and the length of the striplines. Besides, no via-hole was used in this structure, which guarantees the easy fabrication and high production.

Compact meander T-shaped monopole antenna for dual-band WLAN applications

A compact coplanar waveguide-feed monopole antenna with dual-band characteristics is proposed in this article. The proposed antenna mainly consists of meander T-shaped monopole and small ground plane embedded with a pair of L-shaped couple slots and two pairs of I-shaped notched slots symmetrically. By elongating the meander T-shaped arms and carefully selecting the positions and lengths of L-shaped slot and I-shaped slot, the antenna excites four resonant frequencies at 2.42, 2.52, 4.75, and 5.54 GHz which are formed into two wide bands to cover all the 2.4/5.2/5.8 GHz wireless local area network (WLAN) operating bands, and is with miniaturization structure. Moreover, the antenna can provide nearly dipole-like radiation patterns and good gains across the dual operating bands. These results prove that the proposed dual-band antenna is very suitable for WLAN applications. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2013. © 2013 Wiley Periodicals, Inc.

Design of a microstrip-fed monopole antenna with a rectangular slit ground and a rectangular projection strip for dual-band WLAN operations

In this study, a novel dual-band planar monopole antenna for wireless local area network (WLAN) application was designed, fabricated, and measured.The proposed antenna was fabricated on a low-cost, easily available FR4 substrate, which effectively covers both the 2.4GHz and 5.2/5.8-GHz WLAN bands. The proposed antenna consists of two branches, an asymmetric ground plane, a rectangular projection strip, and a rectangular slit in the ground plane. The rectangular projection strip and the rectangular slit in the ground plane were introduced to enhance the performance of the proposed antenna. The obtained numerical results agree well with the experiment data. It was validated that the configuration can meet the demands of WLAN systems and effectively enhanced the impedance bandwidth to 39.7% for the lower band and 23.1% for the upper band when the impedance bandwidth was −10 dB. This article also presents and discusses the 2D radiation patterns and gains according to the results of the experiment that was conducted. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1039–1044, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26725

Design of microstrip-fed monopole antenna with two branch strips and a rectangular slit ground for dual-band WLAN operations

A dual-band planar antenna that was developed for wireless local area network (WLAN) application is presented in this article.The proposed antenna, which has two strip lines for resonance and a rectangular ring strip for matching, was designed to cover the popular frequency spectra of the 2.4 and 5 GHz WLAN bands. Also, an asymmetric ground and a rectangular slit in the ground are introduced to enhance the performance of the proposed antenna. The proposed antenna, which is capable of dual-frequency operation, is fed by a strip line. The obtained numerical results agree well with the experiment data. It was validated that the configuration can meet the demands of WLAN systems and effectively enhanced the impedance bandwidth to 16.8% for the lower band and 58.14% for the upper band when VSWR < 2. This article also presents and discusses the 2D radiation patterns and gains according to the results of the experiment. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26225

CPW Fed Double T-Shaped Array Antenna with Suppressed Mutual Coupling

A compact CPW-fed double T-Shaped antenna is proposed for dual-band wireless local area network (WLAN) operations. For the proposed antenna, the -10 dB return loss bandwidth could reach about 25.5% for the 2.4 GHz band and 5.7 % for the 5 GHz band, which meet the required bandwidth specification of WLAN standard. To reduce the mutual coupling and get high isolation between two dual-band antennas, we proposed the novel electromagnetic band gap (EBG) structures. When the EBG structure is employed, a -13dB and -30dB mutual coupling reduction is achieved at 2.4 and 5.2 GHz. It shows that the features of small size, uniplanar structure, good radiation characteristics and small mutual coupling are promising for multi-input multi-output (MIMO) applications.