GHz WLAN Applications Research Articles

Dual‐port planar MIMO antenna with ultra‐high isolation and orthogonal radiation patterns

A dual-port planar MIMO antenna designed for 2.4 GHz WLAN applications is presented. It consist of two X-shaped arms etched on a square-shaped substrate, which forms a self-decoupled structure that can generate two orthogonal modes with ultra-high isolation. In measurement, the −10 dB bandwidth covers from 2.39 to 2.51 GHz, and better than 43 dB isolation is achieved between the two ports. Meanwhile, the patterns are orthogonal, and the envelope correlation coefficient is only 0.0052. The antenna it is fabricated on FR-4 substrate, and the size is only 33 × 33 × 3.2 mm, which is very much suited to space-limited MIMO applications that require ultra-high isolation, good pattern diversity and low fabrication cost.

A DUAL-POLARIZED MIMO ANTENNA WITH EBG FOR 5.8 GHZ WLAN APPLICATION

A dual-polarized multiple-input-multiple-output (MIMO) antenna integrated with electromagnetic band-gap (EBG) is proposed. The MIMO antenna consists of two dual-polarized (0 ◦ and 90 ◦ polarizations) antenna elements. Each element includes four symmetrical arc-shaped slots. A mushroom-shaped EBG structure with four slots at its fringe is designed to enhance the gain of MIMO antenna. The bandwidth (return loss > 10 dB) of the proposed antenna is from 5.70 to 5.93 GHz, and the peak gain is 5.45 dBi. The isolation between the ports of adjacent antenna elements can be as small as less than �20 dB. The dual-polarized MIMO antenna with EBG has a compact volume of 44.5 × 77.5 × 1. 6m m 3 and can be suitable for 5.8 GHz WLAN application.

Theory and Experiment of Three-Port Polarization-Diversity Cylindrical Dielectric Resonator Antenna

The three-port polarization-diversity cylindrical dielectric resonator antenna (DRA) is presented for the first time. The design makes use of the TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01δ</sub> and HEM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12δ+1</sub> modes of the cylindrical DRA. Using the covariance matrix adaptation evolutionary strategy, engineering formulas are obtained to determine the dimensions of the polarization-diversity cylindrical DRA for a given operating frequency and dielectric constant. To demonstrate the usefulness of the formulas, a three-port polarization-diversity cylindrical DRA was designed at 2.4 GHz for WLAN applications. The TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01δ</sub> mode of the cylindrical DRA is excited with a coaxial probe and an omnidirectional radiation pattern is obtained. Two slot pairs are used to excite the broadside HEM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12δ+1</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sup> and HEM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12δ+1</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</sup> modes of the cylindrical DRA. The reflection coefficient, port isolation, radiation pattern, and antenna gain of the antenna were simulated using ANSYS HFSS, while the envelope correlation was calculated from the S-parameters. Measurements were carried out to verify the simulations, and reasonable agreement between them is observed. Measured results show that the isolation between any two ports of the diversity DRA is over 24 dB across the 10-dB impedance bandwidth. A parameter study was carried out to characterize the proposed DRA.

A Metaresonator Inspired Dual Band Antenna for Wireless Applications

A novel metaresonator inspired dual band antenna for 2.4/5.2 GHz WLAN applications is presented. Dual band operation is achieved by utilizing stacking technique on a dog bone shaped dipole antenna. Stacking excites the magnetic resonance in addition to the existing dipole resonance in the structure yielding the dual band design. The antenna has a 2:1 VSWR bandwidth of 12% for the lower dipole resonance centered around 2.47 GHz and 10.5% for the second resonance at 5.18 GHz which is wide enough to cover the 2.4 GHz and 5.2 GHz WLAN applications. The antenna is made of a low cost FR4 substrate of relative permittivity 4.4 and height 1.6 mm and has a total dimension of 38×40×3.2 mm3. Experimental and simulation studies of the antenna including the stacking height variation and resonant mechanisms are explained in detail in this communication.

Miniature dual‐mode dual‐band bandpass filter with improved passbands performance for 2.4/5.2 GHz WLAN application

ABSTRACTIn this article, a miniature dual‐mode dual‐band bandpass filter (BPF) based on novel complementary center‐stub‐loaded stepped‐impedance resonators has been presented. By loading an open stub at the center of stepped‐impedance resonator, the center frequency of the fundamental even‐mode could be independently controlled, whereas that of the fundamental odd‐mode is fixed. A dual‐mode dual‐band BPF using complementary configuration is implemented with three transmission zeros. To validate the design and analysis, a prototype filter has been designed and fabricated with its two bands located at 2.4/5.2 GHz for WLAN. The measured performances show good agreements with those of the coupling matrix analysis and electromagnetic simulation. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1235–1238, 2014

Compact triple‐band antenna for WiMAX and WLAN applications

A triple-band planar antenna with a compact radiator is proposed for 2.3/3.5/5.5 GHz WiMAX and 5.2/5.8 GHz WLAN applications simultaneously. The proposed antenna consists of an inverted-L (IL)-shaped radiating element and a parasitic element in the ground plane to generate three resonant modes for triple-band operations. Each of the three resonant bands can be tuned separately to cover other wireless applications also. Owing to the coupling of the IL-driven element and the parasitic element, a compact radiator of 10 × 17.3 mm 2 is realised for triple-band operations. Some key parameters affecting the antenna performance have been analysed using computer simulations. To validate the simulation results, the prototypes of the proposed antenna are fabricated on an inexpensive FR-4 substrate and tested. Good radiation characteristics of the proposed antenna have been obtained. The simulated and measured results are in good agreement.

A compact zeroth-order directional antenna

A novel via free, asymmetrical coplanar strip fed zeroth-order directional antenna suitable for 2.4 GHz WLAN applications is presented. The zeroth-order resonance is achieved by realizing a composite right/left-handed transmission line-based interdigital capacitor inserted into the shorted asymmetric coplanar strip. The structural asymmetry provides an improved directivity for the antenna. The prototype made on a low cost substrate of relative permittivity 3.7 and height 1.6 mm with an overall dimension 29 × 16.5 × 1.6 mm3 offers a 2:1 VSWR impedance bandwidth of 280 MHz (2.21–2.49 GHz) and exhibits directional radiation pattern with a peak gain of 3.7 dBi over the entire operating band. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:929–932, 2014

Compact helical antenna with small ground fed by spiral‐shaped microstrip line

A compact helical antenna with a small ground is proposed for 5.2/5.8 GHz WLAN applications. The proposed antenna can be easily mounted in the space-limited systems. Good impedance matching is achieved by a spiral-shaped microstrip line feed structure. Relatively uniform current along the helix is observed owing to the travelling-wave current on the feed structure, which contributes to high-gain performance even with a small ground. The measured 3 dB axial ratio bandwidth and impedance bandwidth for S 11 ≤ −10 dB overlap over 5–6 GHz, whereas the realised gain of about 13–14 dBic is achieved over the 5.2/5.8 GHz WLAN band.

Design and Analysis of a Novel Dual Band-Notched UWB Antenna

A novel ultrawide band (UWB) antenna with dual band-notched characteristics is presented. The first band rejection is provided by an arc H-shaped slot on the radiating patch. The parametric study of the arc H-shaped slot shows that this structure enables rejectband characteristic with improved control compared to traditional H-shaped slot. Based on the single band-notched UWB antenna, the second notched band is realized by etching narrow slots on the ground plane. By tuning the parameters of these slots, the proposed UWB antenna can operate from 2.9 GHz to above 10 GHz, except for the bandwidth of 3.3–3.6 GHz for WiMAX application and 5.1–5.9 GHz for WLAN application. Simulated and measured results show that the proposed antenna provides excellent band rejection and is a good candidate for future UWB application.

Compact CPW fed electrically small antenna for WLAN application

A compact coplanar waveguide (CPW) fed electrically small antenna suitable for 2.4 GHz WLAN applications is presented. The resonance of the structure is achieved by implanting a chip inductor in between the centre conductor of an open-ended CPW transmission line and a short metal strip. The total electrical size of the fabricated antenna is 0.08λ 0 × 0.0479λ 0. The reflection and radiation characteristics of the antenna and a method to enhance the gain are discussed.

A NOVEL SINGLE FEED OMNIDIRECTIONAL CIRCULARLY POLARIZED ANTENNA WITH WIDE AR BANDWIDTH

A novel omnidirectional circularly polarized (CP) antenna with single feed is proposed for 2.4GHz WLAN applications. Based on the zeroth-order resonance (ZOR) mode of epsilon negative (ENG) transmission line (TL), the antenna excites uniform vertically polarized E-fleld just as the monopole does. A modifled Alford loop with electromagnetic coupling fed by L-shaped strip consists of four curved branches, which is placed on the top of the antenna and generates an equivalent horizontally polarized magnetic dipole mode. Once the two orthogonally polarized components are equal in amplitude but difierent in phase by 90 - , omnidirectional CP wave can be obtained. The measured results show that the impedance bandwidth (S11 < i10dB) is 6% (2.38{2.53GHz), and the 3-dB axial ratio bandwidth in the azimuth plane is very wide which achieves 54% (1.60{2.80GHz). Additionally, the 3-dB axial ratio beamwidth is over 50 - for radiation pattern in elevation plane. Moreover, the antenna achieves excellent omnidirectional right-hand CP performance with a variation of 0.5dB in the azimuth plane and an average gain over 1.5dB across the operating band, which are well applied to the wireless system.

Polarization Reconfigurable Patch Antenna for Wireless Sensor Network Applications

Polarization reconfigurable microstrip patch antenna is presented for 2.4–2.5 GHz wireless sensor network and WLAN applications. Dual feed degenerate mode patch is used as the starting point for circular polarization and L-shaped islands which can be connected or disconnected to the main patch via RF switches are placed around the patch. When L-shape structure is connected, the patch radiates in linear polarization modes with either vertical or horizontal polarization depending on the feed being used. When RF switches are not biased, the antenna is in circular polarization mode. Full wave simulations and measurements were carried out to validate the design.

Co-axial Fed Rectangular Microstrip Patch Antenna for 5.2 GHz WLAN Application

In this paper, the design of a co-axial fed single layer microstrip patch antenna (MSA) for 5.2 GHz WLAN application is presented. The impedance matching and the radiation characteristics of this proposed structure are studied and analyzed using Computer Simulation Technology (CST) Microwave Studio, which is a commercially available electromagnetic simulator based on the method of finite difference time domain technique to achieve the desired specification. The proposed antenna based on co-axial feed configuration has the maximum achievable bandwidth obtained about 219.2 MHz (5.14-5.36 GHz) at -10 dB reflection coefficient which corresponds to WLAN 5.2 GHz frequency band and the maximum achievable gain is 5.208 dB. Stable radiation characteristics are obtained across the frequency band.

Design of High Efficiency Two Stage Power Amplifier in 0.13µM RF CMOS Technology for 2.4GHZ WLAN Application

Design of High Efficiency Two Stage Power Amplifier in 0.13µM RF CMOS Technology for 2.4GHZ WLAN Application

Omnidirectional Circularly Polarized Dielectric Resonator Antenna With Top-Loaded Alford Loop for Pattern Diversity Design

A new compact omnidirectional circularly polarized (CP) cylindrical dielectric resonator antenna (DRA) with a top-loaded modified Alford loop is investigated. Fed by an axial probe, the DRA is excited in its TM01δ-mode, which radiates like a vertically polarized electric monopole. The modified Alford loop comprises a central circular patch and four curved branches. It is placed on the top of the DRA and provides an equivalent horizontally polarized magnetic dipole mode. Omnidirectional CP fields can be obtained when the two orthogonally polarized fields are equal in amplitude but different in phase by 90°. This CP DRA is applied to the design of a two-port CP diversity DRA which provides omnidirectional and broadside radiation patterns. The broadside radiation pattern is obtained by making use of the broadside HEM12δ+ 1-mode of the DRA, which is excited by a balanced slot serially fed by a microstrip line. For demonstration, both the omnidirectional CP DRA and the diversity CP DRA were designed at ~ 2.4 GHz for WLAN applications. Their S-parameters, axial ratios, radiation patterns, antenna gains, and antenna efficiencies are studied. The envelope correlation is also found for the diversity design. Reasonable agreement between the simulated and measured results is observed.

Numerical Analysis of Dual Band Mirrored-F Antenna for WLAN and Mobile WiMAX Applications

The numerical simulation of a low-profile dual band mirroredF antenna for 3.5/5.5 GHz WiMAX and 5.2 GHz WLAN applications is proposed. It has a dimension of 29×14.5 mm and the two resonant modes of the antenna provide bandwidth of 13.8% (3.35 GHz-3.85 GHz) and 17.4% (4.9 GHz-5.85 GHz) with maximum gain of 3.36 and 7.35 dBi respectively. The peak values of return loss are -22.124 and -52.282 dB and VSWR varies between 1.83~1.17 and 1.004~1.9 at the lower and upper resonant frequency bands. In addition, the antenna also provides almost omnidirectional radiation characteristics and excellent impedance matching.

Compact Dual-Band Bandpass Filter Using Quadruple-Mode Square Ring Loaded Resonator (SRLR)

A compact quadruple-mode square ring loaded resonator (SRLR) is proposed in this letter. Distinct mode splitting characteristics of the quadruple-mode SRLR are investigated and explained by using even- and odd-mode analysis. It results to excite four resonant modes which are applied to produce two pairs of transmission poles for dual-band bandpass filter (BPF) design. Based on the unique characteristics of the proposed SRLR, a miniaturized dual-band BPF operating at 2.45 GHz and 5.20 GHz for WLAN applications was designed and fabricated. Multiple transmission zeros are generated to improve the selectivity of the filter. Measurements are in good agreement with the simulations. Also, the circuit size occupies only 0.11λg×0.23λg, where λg is the guided wavelength at the center frequency of the first passband.

Quasi‐lumped bandpass filter with sharp transition edge and wide stopband rejection

Presented is a highly miniaturised bandpass filter (BPF) with superior passband selectivity and high rejection over a wide stopband for 2.4 GHz WLAN applications. The proposed third-order coupled resonator design with a cross-coupled path provides an attenuation pole that is very close to the passband. Properly setting the fractional bandwidth and the resonator Q factor yields a sharp transition edge to suppress a 2.1 GHz WCDMA signal. Furthermore, the use of quasi-lumped LC resonators reduces the area of the BPF and generates multiple transmission zeros to enhance the desired stopband rejection.

0.9 GHz and 2.4 GHz dual-band SiGe HBT LNA

This paper presents design and implementation of a dual-band LNA using a 0.35 μm SiGe HBT process for 0.9 GHz GSM and 2.4 GHz WLAN applications. PCB layout parasitic effects have a vital effect on circuit performance and are accounted for using electro-magnetic (EM) simulation. Design considerations of noise decoupling, input/output impedance matching, and current reuse are described in detail. At 0.9/2.4 GHz, gain and noise figure are 13/16 dB and 4.2/3.9 dB, respectively. Both S11 and S22 are below −10 dB. Power dissipation is 40 mW at 3.5 V supply.

Ultralow Phase Noise and Wideband CMOS VCO Using Symmetrical Body-Bias PMOS Varactors

This letter presents an ultralow phase-noise and wide turning-range CMOS voltage-controlled oscillator (VCO) for 5 GHz WLAN applications. The proposed PMOS-only VCO design with body-bias varactors achieves a tuning range of 20.4% and a phase noise of -138.4 dBc/Hz at 1 MHz offset. The total power consumption of the VCO core is 13.1 mW using a 1.8 V supply voltage. The achieved figure of merit with tuning range (FOM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> ) is -207.2 for the proposed CMOS VCO.