Showing papers in "Microwave and Optical Technology Letters in 2011"
TL;DR: In this article, a simple circular-ring planar-monopole antenna, with a compact size of 26 × 28 mm2, fed by an offset-microstrip line, is proposed.
Abstract: A simple circular-ring planar-monopole antenna, with a compact size of 26 × 28 mm2, fed by an offset-microstrip line, is proposed. The antenna is composed of a circular-ring radiator and a ground plane with a small rectangular slot cut along the upper edge for ultra-wideband (UWB) operation. Studies of the antenna are carried out using computer simulation. Prototype of the antenna is used for verification of the simulation results. Results show that the antenna has an impedance bandwidth of more than 132% (from 3.7 to more than 18 GHz) for the standing wave ratio of less than 2 (voltage standing wave ratio, VSWR ≤ 2), a stable omnidirectional radiation pattern and an average peak gain of 3.97 dBi across the UWB, making the antenna a good candidate for use in UWB communications. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2283–2288, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26295
86 citations
TL;DR: In this article, an antenna array comprising a main antenna for eight-band LTE/WWAN operation and an auxiliary antenna to combine with the main antenna in the mobile phone is presented.
Abstract: An antenna array comprising a main antenna for eight-band LTE/WWAN operation and an auxiliary antenna to combine with the main antenna for LTE MIMO operation in the mobile phone is presented. Both the main and auxiliary antennas are disposed at the bottom edge of the system circuit board of the mobile phone and separated by a protruded ground. The main and auxiliary antennas can respectively fit in two small no-ground regions of 15 × 30 mm2 and 15 × 20 mm2 on the system circuit board, while the protruded ground in-between the two antennas has a width of 10 mm for mounting a USB data port. The main antenna covers the 704–960/1710–2690 MHz bands for eight-band LTE/WWAN operation, and the auxiliary antenna covers the 704–787/2300–2690 MHz bands such that the main and auxiliary antennas together can perform LTE MIMO operation in the LTE700/2300/2500 bands. The proposed antenna array is fabricated and tested. Results are presented and discussed. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26038
82 citations
TL;DR: The possibility of mimicking different types of breast tissues to realize experimental phantoms has been investigated by measuring the complex permittivity of polyethylene glycol mono phenyl ether (Triton X-100) and distilled water solutions.
Abstract: The possibility of mimicking different types of breast tissues to realize experimental phantoms has been investigated by measuring the complex permittivity of polyethylene glycol mono phenyl ether (Triton X-100) and distilled water solutions. In this respect, broad band electromagnetic characterization of several mixtures, at different concentrations, has been carried out in the 0.5-12 GHz frequency range. The good fitting between the dielectric properties of mammary tissues and that of the proposed mixtures, and the stability against temperature in the range 18-30 � C, suggest the possibility of mimicking the dielectric characteristics of breast tissues using easily available and low cost materials. V C 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:1276-1280, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26001
66 citations
TL;DR: Using oil‐in‐gelatin dispersions that mimic breast tissue dielectric properties at microwave frequencies, four heterogeneous phantoms spanning the full range of volumetric breast densities are constructed.
Abstract: We present a technique for fabricating realistic breast phantoms for microwave imaging experiments. Using oil-in-gelatin dispersions that mimic breast tissue dielectric properties at microwave frequencies, we constructed four heterogeneous phantoms spanning the full range of volumetric breast densities. We performed CT scans and dielectric properties measurements to characterize each phantom.
63 citations
TL;DR: In this paper, a planar antenna with a multi-slotted ground plane was proposed for UWB applications and the measured results showed that the proposed antenna achieves a bandwidth (VSWR ≤ 2) ranges from 2.57 to 16.72 GHz.
Abstract: A planar antenna with a multi-slotted ground plane has been proposed for UWB applications. The compact antenna having a total size of 30 × 22 mm2 consists of a square patch and a partial ground plane. The rectangular slots on the top side of the ground plane help to increase the bandwidth. The measured result shows that the proposed antenna achieves a bandwidth (VSWR ≤ 2) ranges from 2.57 to 16.72 GHz. Details of the proposed antenna and measured results are presented and discussed. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:966–968, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25950
61 citations
TL;DR: In this article, a composite artificial magnetic conductor (AMC) surface is presented for wide band radar cross section (RCS) reduction, which consists of two kinds of AMC cells with different resonance frequencies.
Abstract: A composite artificial magnetic conductor (AMC) surface is presented for wide band radar cross section (RCS) reduction. The composite surface consists of two kinds of AMC cells with different resonance frequencies. The phase difference between them can be tuned to be within a range close to ±π over a wide bandwidth. Therefore, the reflections from these two different AMC cells cancel each other. The basic principle was discussed and a sample was measured. The results show that a nearly 10 dB RCS reduction was achieved with a 32% bandwidth. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:712–715, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25835
52 citations
TL;DR: In this article, a dual-band frequency-selective surface (FSS) consisting of double rectangular ring elements was used to improve the bandwidth and gain of a U-slot patch antenna.
Abstract: A design strategy using a dual-band frequency-selective surface (FSS) consisting of double rectangular ring elements to improve the bandwidth and gain and to optimize the onsets of two operating frequencies for a U-slot patch antenna is presented.After implanting the FSS in the U-slot patch antenna, it was found that the bandwidths have been improved from 3.14% to 5.51% and 5.48% to 7.48% at resonant frequencies 2.45 and 5.8 GHz, respectively. It was also found that the antenna gain and the onset of operating frequency have been improved for Bluetooth and wireless local area network (WLAN) applications. The U-slot patch antenna implanted with a FSS consisting of double rectangular ring elements is capable of dual-band operations at 2.45 and 5.8 GHz. The radiation patterns are satisfied at these dual bands. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26066
45 citations
TL;DR: In this paper, a modified bow-tie slot antenna with a rectangular tuning stub for 2.4/5.8 GHz triple-band applications is presented, where the antenna consists of a modified Bow-Tie slot, the strip line in the bowtie slot, and the rectangular tuned stub for the feeding.
Abstract: In this article, a novel design for the modified bow-tie slot antenna with a rectangular tuning stub for 2.4/5.2/5.8 GHz triple-band applications is presented. The prototype consists of a modified bow-tie slot, the strip line in the bow-tie slot, and the rectangular tuning stub for the feeding. The simulation results showed that the impedance matching of the proposed modified bow-tie slot antenna was greatly affected by the feed gap and the strip line in the bow-tie slot. The experiment results indicate that the impedance bandwidth (return loss: −10 dB definition) of the proposed antenna was about 1.405 GHz for the 2.4 GHz band and 1.305 GHz for the 5 GHz band. The radiation patterns and gains in the experiment results are also presented and discussed. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:126–130, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25647
43 citations
TL;DR: In this paper, a simple printed monopole slot antenna for penta-band wireless wide area network operation (824-960/1710-2170 MHz) in the mobile handset is presented.
Abstract: A simple printed monopole slot antenna for penta-band wireless wide area network operation (824–960/1710–2170 MHz) in the mobile handset is presented.The monopole slot has a length of 50 mm only and is embedded close to the bottom edge of the system ground plane of the handset with a small distance of 11 mm. By adding a small-size C-shaped strip connected orthogonal to the bottom edge of the system ground plane, good excitation of the monopole slot antenna at its fundamental (0.25 wavelength) and higher-order resonant modes can be obtained. The excited resonant modes form two wide operating bands to cover the GSM850/900 operation (824–960 MHz) and GSM1800/1900/UMTS operation (1710–2170 MHz). Detailed operating principle and radiation characteristics including the specific absorption rate results of the proposed monopole slot antenna are described. Measured results of the fabricated antenna are also presented. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:1399–1404, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26017
42 citations
TL;DR: In this article, a defected microstrip structure (DMS) is used to design a bandstop filter, which can be adjusted by changing the dimension of the structure unit.
Abstract: In this article, a new defected microstrip structure (DMS) which is used to design filter is introduced.Its resonant characteristics can be adjusted by changing the dimension of the structure unit. A novel bandstop filter is designed based on this structure. There are two transmission zeros located at about 4.08 GHz and 6.2 GHz, respectively. The measured results show a good agreement with the simulation. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:433–435, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25708
37 citations
TL;DR: In this article, an equivalent circuit model is developed to account for the device nonlinearities at microwave frequencies, including bias dependence of both low-frequency (LF) dispersive effects affecting GaN devices and HF nonquasi-static effects, since these two types of frequency dependent phenomena play a crucial role under microwave large-signal condition.
Abstract: The purpose of this study is to present an advanced technique for accurately modeling the behavior of a GaN HEMT under realistic working conditions. Since this semiconductor transistor technology has demonstrated to be very well suited for high-frequency (HF) high-power applications, an equivalent circuit model is developed to account for the device nonlinearities at microwave frequencies. In particular, the proposed model includes bias dependence of both low-frequency (LF) dispersive effects affecting GaN devices and HF nonquasi-static effects, since these two types of frequency dependent phenomena play a crucial role under microwave large-signal condition. The extraction procedure consists of two main steps. First, an accurate multibias small-signal nonquasi-static equivalent circuit is analytically extracted from scattering parameters measured under a wide range of bias points. Thereafter, this linear model is used as a cornerstone for building a nonlinear nonquasi-static equivalent circuit, which is expanded to account for the LF dispersive phenomena by using an empirical formulation directly identified from the HF large-signal measurements. The accuracy of the proposed modeling approach is completely and successfully verified by comparing model simulations with LF and HF large-signal measurements. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:692–697, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25757
TL;DR: In this paper, a multi-slotted dual-patch tag antenna is designed for a 1.6mm-thick substrate, and it can be mounted on metal without degradation in performance.
Abstract: This article presents an RFID (Radio Frequency Identification) tag antenna, which works in the 902–928 MHz band. The multi-slotted dual patch tag antenna is designed for a 1.6-mm-thick substrate, and it can be mounted on metal without degradation in performance. Due to a low-profile and simple structure, this antenna has more potential for mass production compared to earlier antenna designs. It is shown by simulations how the bandwidth can be increased by incorporating multiple slots in the radiating patch elements of the antenna. Design curves showing the effect of different tuning parameters on the tag performance are presented. The performance of the tag is evaluated both in free-space and on metal plate and the simulated input impedance, power reflection and radiation patterns are presented. A prototype of this multi-slotted dual patch tag antenna has been constructed and impedance measurements are performed for the proposed tag in free-space and on metal plate. Finally, maximum readable distances for the tag are calculated. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:40–47, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25622
TL;DR: In this article, a planar monopole antenna with band-notched characteristics was proposed for ultra-wideband applications with a small size of 30 mm × 39.3 mm, which operates from 2.57 to over 12 GHz with return loss larger than 10 dB and the radiation patterns similar to that of dipole antennas.
Abstract: In this article, a compact planar monopole antenna for ultra-wideband applications with band-notched characteristic is presented. The antenna with a small size of 30 mm × 39.3 mm operates from 2.57 to over 12 GHz with return loss larger than 10 dB and the radiation patterns similar to that of dipole antennas. A pair of ground stubs locating along the edge of the ground plane is used to create the band-notch characteristic. The band notch covers the wireless area network band from 5.15 to 5.825 GHz. The center-notch frequency and notch bandwidth can be adjusted using the dimensions of the ground stubs. Prototype of the proposed antenna is designed, fabricated, and studied. The band-notched characteristics, return loss, radiation patterns, peak gains, and efficiencies of the antenna are studied using both computer simulation and measurements. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:523–529, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25817
TL;DR: In this article, a technique for the measurement of scattering parameters of an infinite reflectarray is presented which takes into account effects of mutual coupling.
Abstract: A technique for the measurement of scattering parameters
of an infinite reflectarray is presented which takes into account effects of mutual coupling. Infinite reflectarrays designed at 10 GHz with different substrate thicknesses have been analyzed in which maximum 10% and 20% bandwidth values from resonance are shown to be 157 MHZ and
250 MHz, respectively, constructed on 0.508-mm thick substrate.Moreover, a figure of merit (FOM) has been defined which decreases from 0.320 to 0.26/MHz as the substrate thickness is increased from 0.127 to 0.508 mm, and the results demonstrate a significant decrease in the slope of reflection phase curve.
TL;DR: In this article, a single-layer rectangular microstrip patch antenna has been proposed, which uses a ground plane with a single slot and has been shown that by using this slotted ground plane, the resonant frequency has been lowered considerably, thus, reducing the size of the antenna.
Abstract: In this article, a new design for single-layer rectangular microstrip patch antenna has been proposed.This design uses a ground plane with a single slot. It has been shown that by using this slotted ground plane, the resonant frequency has been lowered considerably, thus, reducing the size of the antenna. Using this design, the size of the antenna is reduced by about 90%. It has been also shown that the resonant frequency can be reduced further by increasing the length of the slot. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:111–115, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25661
TL;DR: In this article, an on-board uniplanar printed mobile handset antenna with a small size of 15 × 30 mm2 for 8-band long-term evolution/wireless wide area network (LTE/WWAN) (698-960/1710-2690 MHz) operation is presented.
Abstract: An on-board uniplanar printed mobile handset antenna with a small size of 15 × 30 mm2 for 8-band long term evolution/wireless wide area network (LTE/WWAN) (698–960/1710–2690 MHz) operation is presented.The antenna is a spiral monopole coupled with a long parasitic shorted strip. The spiral monopole has a length of 78 mm (about 0.25 wavelength at 950 MHz), while the shorted strip capacitively excited by the spiral monopole has a length of 125 mm (close to 0.25 wavelength at 700 MHz). The spiral monopole is encircled by the shorted strip so that the antenna has a compact configuration to fit in a small no-ground portion at the corner of the bottom edge of the main circuit board in the mobile handset. In addition, the antenna is closely integrated with the system ground plane on the main circuit board and is spaced by a small distance of 0.5 mm to the nearby system ground plane. This leads to compact integration of the on-board LTE/WWAN printed antenna on the main circuit board of the mobile handset. Results of the proposed antenna including its specific absorption rate and hearing aid compatibility behavior are presented and discussed. The antenna is about the smallest for the on-board all-printing LTE/WWAN handset antennas that have been reported for the present. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:1336–1343, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25961
TL;DR: In this article, a tapered slot antenna is used in ultra wideband microwave imaging systems aimed for early breast cancer detection, and the mutual coupling effects between the antennas are investigated to verify the feasibility of the antenna for medical imaging applications.
Abstract: A tapered slot antenna to be used in ultra wideband microwave imaging systems aimed for early breast cancer detection is presented. A synthetic array is designed to operate across the ultra wideband frequency band in the air. The mutual coupling effects between the antennas have been investigated to verify the feasibility of the antenna for medical imaging applications. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:639–643, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25770
TL;DR: In this paper, a WWAN/LTE printed loop antenna for tablet computer application is presented, which is a halfwavelength loop strip coupled-fed by a patch monopole, which performs not only as a coupling feed but also as an efficient radiator for the antenna.
Abstract: A WWAN/LTE printed loop antenna for tablet computer application is presented.The printed loop antenna is a half-wavelength loop strip coupled-fed by a patch monopole, which performs not only as a coupling feed but also as an efficient radiator for the antenna. By embedding a printed distributed inductor in the loop strip, dual-resonance excitation of the half-wavelength mode of the coupled-fed loop antenna is obtained, which forms the antenna's lower band at about 800 MHz to cover the LTE700/GSM850/900 operation (704–960 MHz). The antenna's upper band is formed by both the resonant modes contributed by the patch monopole and the higher order resonant modes contributed by the loop strip. The upper band shows a large bandwidth (>1 GHz) to cover the GSM1800/1900/UMTS/LTE2300/2500 operation (1710–2690 MHz). Further, with a planar and compact structure (12 × 75 mm2), the antenna is suitable to be disposed in the limited space inside the tablet computer and meets the body specific absorption rate (SAR) requirement (<1.6 W/kg for 1-g body tissue) for practical applications. Details of the proposed antenna and its body SAR results are presented. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2912–2919, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26377
TL;DR: In this paper, a coupled dual-U-shaped antenna for WiMAX triple-band operation is presented, which is composed of two U-shaped radiating elements based on a 50-Ω microstrip-fed line on FR4 substrate.
Abstract: A coupled dual-U-shaped antenna for WiMAX triple-band operation is presentedThe proposed antenna is composed of two U-shaped radiating elements based on a 50-Ω microstrip-fed line on FR4 substrate By using the coupling between the inner and the outer U-shaped antennas, which mainly generate three different resonant modes, the optimized matching characteristic is obtained The experimental results such as the matching characteristic and radiation pattern of the proposed antenna are presented © 2011 Wiley Periodicals, Inc Microwave Opt Technol Lett 53:745–748, 2011; View this article online at wileyonlinelibrarycom DOI 101002/mop25842
TL;DR: In this article, a multiresonance slot antenna for ultra wideband (UWB) applications is proposed, which consists of a modified radiating patch a ground plane with four L-shaped slots which provides a wide usable fractional bandwidth of more than 135% (2.89-14.53 GHz).
Abstract: A novel multiresonance slot antenna, for ultra-wideband (UWB) applications is proposed.The proposed antenna consists of a modified radiating patch a ground plane with four L-shaped slots which provides a wide usable fractional bandwidth of more than 135% (2.89–14.53 GHz). By cutting four modified L-shaped slot with variable dimensions on the corners of ground plane, additional resonances are excited and hence much wider impedance bandwidth can be produced, especially at the middle band unlike other antennas reported in the literature to date, the proposed antenna displays a good omnidirectional radiation pattern even at higher frequencies. The designed antenna has a small size of 35 × 35 mm2. Simulated and experimental results obtained for this antenna show that it exhibits good radiation behavior within the UWB frequency range. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26214
TL;DR: In this paper, a dual-wideband internal antenna formed by a simple two-strip monopole and a parasitic shorted strip for eight-band long tern evolution/wireless wide area network operation (698-960/1710-2690 MHz) in the laptop computer is presented.
Abstract: A dual-wideband internal antenna formed by a simple two-strip monopole (a longer strip and a shorter strip) and a parasitic shorted strip for eight-band long tern evolution/wireless wide area network operation (698–960/1710–2690 MHz) in the laptop computer is presented.The parasitic shorted strip is excited capacitively by the shorter strip of the two-strip monopole and contributes two resonant modes to the antenna, with one in the lower band and one in the upper band, thereby effectively widening the bandwidths of the antenna's two operating bands. Further, the parasitic strip short-circuited to the top shielding metal wall of the display ground in the laptop computer is configured such that its end section with the shorting point is positioned at the side edge of the antenna. This configuration allows the antenna to be placed closely to a nearby grounded plate, with very small effects on the performances of the antenna. This is an advantage for the proposed antenna in practical applications since the antenna requires a very small isolation distance at its side edge to nearby metal objects (such as a metal screw at the top shielding metal wall to fix the display ground to the casing of the laptop computer). Hence, in addition to the small antenna volume of 4 × 12 × 70 mm3 at the top shielding metal wall, compact integration of the proposed antenna along the shielding metal wall of the display ground can also be obtained. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:706–712, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25836
TL;DR: In this paper, a planar bandpass filter is implemented by the combination of three different electromagnetic structures, namely, substrate-integrated waveguide (SIW), square complementary split-ring resonators (CSRRs) and dumbbells slot.
Abstract: A compact planar bandpass filter is presented in this letter, which is implemented by the combination of three different electromagnetic structures, saying, substrate-integrated waveguide (SIW), square complementary split-ring resonators (CSRRs) and dumbbells slot.The resonator is formed by a SIW cavity loaded with some complementary split-ring resonators (CSRRs) on its top metal plane, causing a stopband with a very sharp rejection. Meanwhile, several dumbbells are etched on the bottom plane of SIW just below each CSRR to enhance the coupling. Double-sided parallel strip line (DSPSL) is also used to excite the SIW and guarantee good propagation between these two different structures. An X-band prototype is designed and fabricated for demonstration, good agreement is observed between simulation and measurement, indicating a very wide rejection band ranging from 11 GHz to 23 GHz and quite strong suppression to spurious modes. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26079
TL;DR: In this article, the authors present two related techniques for the simultaneous measurement of strain and temperature: (1) using two singlemode-multimode-singlemode (SMS) fiber structures accompanied with an optical spectral analyzer (OSA); (2) using three SMS fiber structures and a ratiometric power measurement system.
Abstract: This article presents two related techniques for the simultaneous measurement of strain and temperature: (1) using two single-mode–multimode–single-mode (SMS) fiber structures accompanied with an optical spectral analyzer (OSA); (2) using three SMS fiber structures and a ratiometric power measurement system.Experimental results show that (1) the technique accompanied with an OSA has a resolution of 1.64 μe for strain in the range from 0 to 1000 μe and 0.11°C for temperature and (2) the technique based on ratiometric system offers a resolution of better than 2 μe for strain measurements in the range from 0 to 1000 μe and a resolution better than 0.84°C for temperature. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26205
TL;DR: In this article, a 50 GHz electric field tunable ferrite-piezoelectric phase shifter based on a bilayer of single crystal M-type hexagonal barium ferrite (BaM) and lead zirconate titanate (PZT) is discussed.
Abstract: A 50-GHz electric field tunable ferrite-piezoelectric phase shifter based on a bilayer of single crystal M-type hexagonal barium ferrite (BaM) and lead zirconate titanate (PZT) is discussedA dc voltage applied to PZT results in a piezoelectric strain that manifests as an anisotropy field in BaM A change in the voltage applied to PZT gives rise to variations in the anisotropy field and permeability of BaM and, therefore, a differential phase shift A phase shift of 45° is measured when the voltage is increased from 0 to 400 V across a 05-mm thick PZT Theoretical estimates of the phase shift are in agreement with the data © 2010 Wiley Periodicals, Inc Microwave Opt Technol Lett 53:261–264, 2011; View this article online at wileyonlinelibrarycom DOI 101002/mop25725
TL;DR: The integration of the inexact Newton method within a multiscaling strategy is assessed in the framework of the contrast-field formulation of the electromagnetic inverse scattering to suitably face the nonlinearity and the illposedness/ill-conditioning issues of the imaging problem.
Abstract: The integration of the inexact Newton method within a multiscaling strategy is assessed in the framework of the contrast-field formulation of the electromagnetic inverse scattering. By using the features of the integrated approach, the technique is expected to suitably face the nonlinearity and the illposedness/ill-conditioning issues of the imaging problem. A numerical validation dealing with experimental data related to different objects is carried out to provide evidence of the method premises pointing out features and potentialities as well as current limitations. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2834–2838, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26435
TL;DR: In this paper, a tri-band bandpass filter using asymmetric stepped-impedance resonators (SIRs) with one-step discontinuity is presented, where only two SIRs are needed in the filter structure and the measured results are in good agreement with the full-wave simulation results.
Abstract: This paper presents a simple method to design a tri-band bandpass filter (BPF) using asymmetric stepped-impedance resonators (SIRs) with one-step discontinuity.Only two SIRs are needed in the filter structure. The tri-band passband responses can be achieved by properly selecting the length ratio (u) and the impedance ratio (R) of the asymmetric SIRs. The performances can be further well tuned by the lengths of two enhanced coupling structure and gap of two asymmetric SIRs. A filter example for the applications of GSM at 1.8 GHz, WiMAX at 3.5 GHz and WLAN at 5.2 GHz was designed and fabricated. The measured results are in good agreement with the full-wave simulation results. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26037
Abstract: New method for design and realizing multiband metamaterial is presented.For this purpose, resonator-based metamaterial is designed and investigated by both simulation and experiment with well agreement. By serially arranging the nonconcentric open loop metallic elements with different dimensions, the structure exhibits multipassbands related to the metamaterials' unique features. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2255–2258, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26296
TL;DR: In this article, a simple microstrip fed printed monopole antenna for the radio frequency identification (RFID) and wireless local area network (WLAN) is presented, which has two different resonant current paths (forming an F-shaped structure) that support two resonances at 2.44 and 5.18 GHz, respectively.
Abstract: A simple microstrip fed printed monopole antenna for the radio frequency identification (RFID) and wireless local area network (WLAN) is presented.The antenna has two different resonant current paths (forming an F-shaped structure) that support two resonances at 2.44 and 5.18 GHz, which are reserved for RFID and WLAN applications, respectively. Effectively omnidirectional radiation pattern and large impedance bandwidth has been observed both from simulation and experimental results. Impedance bandwidth for center frequency of 2.44 and 5.18 GHz are 0.65 GHz (2.12–2.77 GHz) and 0.59 GHz (4.91–5.50 GHz), respectively. The proposed antenna is simple in design and compact in size; providing broadband impedance matching, consistent omnidirectional radiation patterns and appropriate gain characteristics (>1.5dBi) in the RFID and WLAN frequency regions. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26060
TL;DR: In this paper, a printed monopole antenna with super wideband performance is presented for various ultra wideband communication applications, and the antenna structure consists of a hexagonal patch radiator with a modified 50 Ω coplanar waveguide line for excitation.
Abstract: This letter presents a new printed monopole antenna with super-wideband performance useful for various ultra wideband communication applications. The antenna has a compact structure, and the total size is 24 × 24 × 1.6 mm3. The antenna structure consists of a hexagonal patch radiator with a modified 50 Ω coplanar waveguide line for excitation. By using a trident shaped feed line structure the super wide bandwidth is obtained. Measurement results show that the impedance bandwidth for S11 ≤ −10 dB is enhanced largely to more than 174%. Radiation patterns are given at 4, 6, and 9.5 GHz. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26090
TL;DR: In this paper, a low-profile high-gain, end-fire Yagi-Uda antenna array designed for an on-body communication link at 60 GHz is described.
Abstract: A novel low-profile high-gain, end-fire Yagi–Uda antenna array designed for an on-body communication link at 60 GHz is described. The antenna consists of four single Yagi antennas, which is composed of a driven dipole, 18 directors, and a reflector. Simulation and measurement in free space show a good agreement, and 15 dBi gain is achieved. Measurements with a body tissue phantom have been done to investigate the antenna's performance in close proximity to the human body. Results show that the reflection coefficient changes a little, whereas the radiation pattern in the H plane is affected. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2728–2730, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26443