GHz Wireless Local Area Network Research Articles

Radio-frequency front-end for 5 GHz wireless local area network transceivers

A transceiver front-end for 5 GHz wireless local area network applications has been designed and implemented in a low-cost 46 GHz fT pure-silicon bipolar technology. The transceiver front-end adopts a superheterodyne sliding-IF architecture and consists of a down-converter, an up-converter and an LO frequency synthesiser. By exploiting a 1 bit variable-gain low-noise amplifier, the down-converter is able to provide an excellent noise figure of 4 dB while ensuring an input 1 dB compression point of −10 dBm with a current consumption of 25 mA from a 3 V supply voltage. The transmitter front-end is implemented by means of a current-reuse variable-gain up-converter. The circuit provides an output 1 dB compression point of 5.3 dBm although consuming only 45 mA from a 3 V supply voltage. Moreover, a linear-in-dB gain control characteristic is achieved over a 35 dB dynamic range. The LO frequency synthesiser is implemented by means of an integer-N phase-locked loop. It features a phase noise of −117 dBc/Hz at 1 MHz offset from the centre frequency of 4.1 GHz and exhibits a tuning range of 1.2 GHz, from 3.47 to 4.65 GHz. The LO frequency synthesiser draws 20 mA from a 3 V supply voltage.

CPW-FED MULTI-BAND OMNI-DIRECTIONAL PLANAR MICROSTRIP ANTENNA USING COMPOSITE METAMATERIAL RESONATORS FOR WIRELESS COMMUNICATIONS

A novel approach for the design of a compact multiband planar microstrip antenna is presented. This type of antenna is composed of composite metamaterial resonators (including conditional microstrip resonators and metamaterial resonators), and fed by signal feed. A sample antenna with composite closed-ring resonator and split-ring resonator (SRR) fed by 50 Ω coplanar waveguide (CPW) developed on FR4 epoxy substrate for multi-band wireless communication applications is presented. Appropriate design of the composite structure resulted in three discontinuous resonant bands. The fundamental magnetic resonant and electric resonant frequency of SRR and the first electric resonant frequency of the closed-ring resonator were combined to form low, middle, and high resonant band. The properties of this antenna are investigated by theoretical analysis and finite element method (FEM) simulations. The numerical results show that the proposed antenna has good impedance bandwidth and radiation characteristics in the three operating bands which cover the required band widths of the 2.4/5.2/5.8GHz wireless local-area networks (WLAN) and 3.5/5.5 GHz worldwide interoperability for microwave access (WiMax) with return loss of better than 10 dB. The antenna also has stably omni-directional H-plane radiation patterns within the three operating bands.

Dual-band Back-to-back F-shaped Antenna with Elliptic Conductor-backed Plane for WLAN/WIMAX Applications

A novel printed antenna with dual widebands is proposed and studied for simultaneously satisfying wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) applications. In this study, the configuration consists of a back-to-back F-shaped monopole antenna with a microstrip feedline for excitation and an elliptic conductor-backed plane for band broadening. This antenna has a satisfactory impedance bandwidth sufficiently cover the 2.4/5.2/5.8 GHz WLAN bands and 2.5/3.5/5.5 GHz WiMAX bands.

A NEW TRIPLE-BAND CPW-FED MONOPOLE ANTENNA FOR WLAN and WiMAX APPLICATIONS

A new CPW-fed antenna with triple-band is presented for simultaneously satisfying wireless local area network (WLAN) and world interoperability for microwave access (WiMAX) applications. The investigated antenna consists of a T-shaped monopole with a trapeziform ground plane and two parasitic elements to generate tripleband. The design methodology is outlined and the overall size is 32× 15× 1 mm3. This antenna was numerically designed using Ansoft HFSS simulation software package. The measured 10 dB bandwidth for return loss is from 2.35 to 2.71 GHz and 3.35 to 3.72 GHz and 4.9 to 6.1 GHz, covering all the 2.4/5.2/5.8 GHz WLAN bands and 2.5/3.5/5.5GHz WiMAX bands.

Dual-Band Printed Bent Slots Antenna for Wlan Applications

A novel printed antenna with bent slots in the ground plane for satisfying wireless local area network (WLAN) applications has been proposed and studied. In this paper, the configuration consists of a microstrip feedline for excitation and bent slots in a ground plane for band broadening. The designers could obtain a preferable bandwidth which covers 2.4/5.2/5.8 GHz WLAN bands sufficiently in a smaller design via enhanced electromagnetic coupling between two bent slots. In addition, an approximately omni-directional radiation pattern is obtained.

Frequency notched wide slot antenna for UWB/2.4 GHz WLAN applications

A compact frequency notched microstrip slot antenna for ultra-wideband (UWB) /2.4 GHz-band wireless local area network (WLAN) applications is proposed. The antenna is similar to a conventional microstrip slot antenna; however, by introducing a cross wide slot and a meandered-slotted stub, both compact size and frequency notched function can be achieved. It has been studied both numerically and experimentally for its impedance bandwidth, surface current distribution, radiation patterns, and gain. As will be seen, an operation bandwidth of over 4.6:1 ranging from 2.39 to 11.25 GHz for return loss lower than -10 dB having a frequency notched band ranging from 4.75 to 5.85 GHz has been achieved, and good radiation performance over the entire frequency range has also been achieved.

Performance limits of pico-cell systems using radio-over-fiber techniques with an electroabsorption modulator

We investigate the performance limits of a pico-cell system using the radio- over-fiber technique with an electroabsorption modulator (EAM) in a 2.4 GHz wireless local area network (WLAN) environment. To understand the performance limits of the system using an EAM as the optical transceiver, we vary the optical modulation index (OMI) of the transmitter for different bias voltages to the EAM. Power margins in the links are found to estimate a possible service range, and packet loss rates (PLRs) in the pico-cell system are measured to evaluate the transmission performance. The total service range can be extended up to 3 m by adjusting the OMI of the transmitter for different applied bias voltages to the EAM.

Reconfigurable Multiband Antenna Designs for Wireless Communication Devices

New designs for compact reconfigurable antennas are introduced for mobile communication devices. The uniqueness of the antenna designs are that they allow various groups of their operating frequency bands to be selected electronically. In particular, each group of frequency bands, or mode, can be made to serve several different communication systems simultaneously. These systems may include various combinations of GSM, DCS, PCS, UMTS, Bluetooth, and wireless local-area network (LAN). Therefore, by electronically selecting different antenna modes, a variety of communication systems can be conveniently served by only one antenna. One advantage is that through the different operational modes, the total antenna volume can be reused, and therefore the overall antenna can be made compact. In these designs, the selection of the different modes is achieved by either i) switching different feeding locations of the antenna (switched feed) or ii) switching or breaking of the antenna's connection to the ground (switched ground). This paper demonstrates these two designs. For the first design of switched feed, it can support GSM, DCS, PCS, and UMTS. In the second design, the antenna makes use of a switched-ground technique, which can cover GSM, DCS, PCS, UMTS, Bluetooth, and 2.4 GHz wireless LAN. The designs are investigated when ideal switches and also various realistic active switches based on PIN diodes, GaAs field effect transistor, and MEMs configurations. The designs are verified through both numerical simulations and measurement of an experimental prototype. The results confirm good performance of the two multiband reconfigurable antenna designs.

Broadband dual‐frequency CPW‐FED antenna with a cross‐shaped feeding line for WLAN application

AbstractA novel and simple design of a coplanar waveguide‐fed planar monopole antenna with broadband dual‐frequency operation for wireless local area network (WLAN) application is proposed. Good impedance matching for dual‐resonance mode is obtained by feeding the radiating patch with a cross‐shaped strip line. Prototypes of the obtained design have been constructed and experimentally studied. The measured results explore broad dual‐frequency operation with (10 dB impedance bandwidths of 30%, ranging from 2.23 to 2.96 GHz, and 56.7%, ranging from 4.6 to 7.62 GHz, at bands of 2.43 and 5.33 GHz, respectively, which cover the 2.4/5.2/5.7 GHz WLAN operating bands, and show good agreement with the numerical prediction. Good monopole‐like radiation patterns and sufficient antenna gains over the operating bands have also been observed. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1739–1744, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22551

Two PIFA-Related Miniaturized Dual-Band Antennas

There are two novel printed inverted-F antenna (PIFA) related dual-band antennas for 2.45 and 5.25 GHz wireless local area network (WLAN) applications introduced in this paper. One is designed by spiraling the tail of the PIFA and the other is by modifying the feed structure of the PIFA into a coupling configuration. An equivalent transmission line model is proposed to explain the dual-band operation of the spiraling PIFA. The measurement results show that the former antenna has a 10 dB return loss with bandwidth 140 MHz in the 2.45 GHz frequency band and bandwidth 756 MHz at 5.25 GHz, whereas the latter one has the bandwidth 240 MHz at 2.45 GHz and bandwidth 672 MHz at 5.25 GHz. In addition, omnidirectional radiation patterns are achieved at those operating frequency bands with average antenna gains near 0 dBi. The proposed antenna possesses the properties of good performance, compact size (about 50% of a typical PIFA), low profile, and low cost; hence, it is suitable for practical applications in a combo WLAN system

Broadband coplanar waveguide‐fed slot antenna for wireless local area networks and microwave imaging applications

AbstractA broadband CPW‐fed semicircular slot antenna is proposed for 2–6 GHz WLAN (wireless local area networks) and microwave imaging applications. The total dimension of the bidirectional slot antenna is 80 mm by 50 mm and is designed on a 0.5‐mm‐thick Duroid 5880 substrate (dielectric constant = 2.2). The antenna operates from 2 to 6 GHz within VSWR of 2.5:1. The same antenna on a combination rectangular cylindrical cavity with cavity depth of 10 mm provides a directional beam, 11 dB front‐to‐back (F/B) ratio and a bandwidth of 63% (2.8–5.4 GHz). © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 846–852, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22276

Compact meander monopole antenna for tri‐band WLAN application

AbstractA novel printed meander monopole antenna for tri‐band wireless local area network (WLAN) applications is presented. The antenna is composed of a meander strip and a straight strip with a gap between the ends of them, both printed on an inexpensive FR4 substrate, and is fed by a 50 Ω microstrip feeder with the notched ground plane. The operation bandwidth of the proposed antenna covers 2.4, 5.2, and 5.8 GHz WLAN bands with light weight and compact radiator size of only 12 × 7 mm2. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 986–988, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22314

A Novel Planar Monopole Antenna with an H-shaped Ground Plane for Dual-band Wlan Applications

A novel dual-band design of planar monopole antenna is presented in this paper. Printed on a dielectric substrate and fed by a 50 Ω microstrip line, a planar monopole antenna is demonstrated to generate two separate resonant modes to cover 2.4/5.2 GHz WLAN (wireless local area network) bands with satisfactory radiation properties. The impedance bandwidths of the proposed antenna are 600 MHz centered at 2.65Hz and 1.15GHz centered at 5.12 GHz for S 11 < −10 dB. The parameters which affect the performance of the antenna in terms of its frequency domain characteristics are investigated.

A Novel Patch Antenna with a T-shaped Parasitic Strip for 2.4/5.8 GHz WLAN Applications

A novel dual-band design of patch antenna is presented in this paper. Using a T-shaped parasitic strip, the patch antenna is able to generate two separate resonant modes to cover 2.4/5.8 GHz (wireless local area network) WLAN bands with satisfactory radiation properties. The impedance bandwidth of the proposed antenna is 250MHz centered at 2.42 GHz and 750MHz centered at 5.78 GHz for S11 < −10dB. The parameters which affect the performance of the antenna in terms of its frequency domain characteristics are investigated.

Novel Dual-Band and Broad-Band Designs of Circle Slot Antenna with a Cross-Shaped Stub

Novel dual-band and broad-band designs of a slot antenna with a cross-shaped stub are presented in this paper. For dual-band operation, the antenna's operating frequency ratio can be tuned by adjusting size of the cross-shaped stub. When proper design is achieved, the antenna can generate two separate resonant modes to cover 2.4/5.2 GHz (wireless local area network) WLAN bands. The simulated impedance bandwidths of the proposed antenna are 260 MHz centered at 2.44 GHz and 610 MHz centered at 5.36 GHz for S11 < −10 dB. Furthermore, it is found that two separate resonate frequencies can be connected to cover the frequency ranges of the digital communication system, personal communication system, international mobile telecommunication, and 2.4GHz WLAN. The bandwidth of the wideband antenna is 1.49 GHz centered at 2 GHz. Details of the proposed dual-frequency and broad-band designs are described and simulation results are presented and discussed in this paper.

A Microstrip Fed Monopole Patch Antenna with three Stubs for Dual-band WLAN Applications

A microstrip fed dual-band design of monopole patch antenna with three stubs is presented in this paper. Printed on a dielectric substrate and fed by a 50 Ω microstrip line, a rectangular patch antenna with 3 stubs is demonstrated to generate two separate resonant modes to cover 2.4/5.2/5.8 GHz (wireless local area network) WLAN bands with satisfactory radiation properties. The impedance bandwidth of the proposed antenna is 400 MHz at 2.4 GHz band (2250–2650 MHz, 16.3%) and 920 MHz at 5 GHz band (4990–5910 MHz, 16.9%). The performances of this antenna are highly desirable for 2.4 and 5 GHz dual-band WLAN applications. The parameters which affect the performance of the antenna in terms of its frequency domain characteristics are investigated in this paper.

COMPACT RING MONOPOLE ANTENNA WITH DOUBLE MEANDER LINES FOR 2.4/5 GHZ DUAL-BAND OPERATION

A novel compact ring monopole antenna with double meander lines is proposed for wireless local area networks (WLAN) applications in IEEE 802.11b/g/a systems. The designed antenna, fed by a 50 Ω microstrip transmission line, is only 32 mm in height and 16 mm in width. By introducing a horizontal and a vertical branched strips to a closed rectangular strip ring, the proposed antenna can generate two separate impedance bandwidths. Prototypes of the proposed antenna have been constructed and tested. The obtained impedance bandwidths reach about 12% for the 2.4 GHz band and 45.3% for the 5 GHz band, which meet the required bandwidth specification of 2.4/5 GHz WLAN standard. Also, good radiation performance and antenna gain over the two frequency ranges have been obtained.

Dual Wideband Printed Monopole Antenna for WLAN/WiMAX Applications

A novel printed monopole antenna with dual widebands is presented for simultaneously satisfying wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) applications. The antenna structure consists of a rectangular monopole with a microstrip feedline for excitation and a trapezoid conductor-backed plane for band broadening. The measured 10 dB bandwidth for return loss is from 2.01 to 4.27 GHz and 5.06 to 6.79 GHz, covering all the 2.4/5.2/5.8 GHz WLAN bands and 2.5/3.5/5.5 GHz WiMAX bands

Hexagonal dielectric resonator antenna for 2.4 GHz WLAN applications

AbstractA dielectric resonator antenna (DRA) with hexagonal geometry for WLAN applications is proposed. The antenna is excited with a simple 50 Ω microstrip transmission line. The proposed antenna produces an impedance bandwidth of 105 MHz from 2.395 to 2.50 GHz, which covers the 2.4 GHz wireless local area networks band (WLAN: 2.4–2.485 GHz). The radiation patterns are measured and are found to be omnidirectional. An average gain of 5.4 dBi is measured in the operating band. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 162–164, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22095

A New Class of Miniature Embedded Inverted-F Antennas (IFAs) for 2.4 GHz WLAN Application

A new class of miniature printed embedded inverted-F antennas are proposed for operation in the 2.4-2.485 GHz wireless local-area network band. One of the proposed antennas on FR4 substrate (dielectric constant = 4.4) measures 9.2 mm by 4.1 mm and has a bandwidth of 3.5%. The peak gain of this antenna is 1.4 dBi. An overall size reduction of 70% is achieved compared to a conventional inverted-F antenna. Effects of dielectric loss tangent and material conductivity on the bandwidth and efficiency of these antennas are also investigated. Finally, two embedded antenna elements are analyzed to demonstrate the feasibility for a decoupled antenna pair consisting of switched and combining diversity schemes