A small size and low profile antenna has been developed in order to provide any mobile phone with... more A small size and low profile antenna has been developed in order to provide any mobile phone with UHF RFID reader functionality. For that purpose, a patch antenna topology has been chosen on account of the mobile phone battery, which exhibits an electromagnetic behavior similar to a metal plane. The low profile patch antenna has been designed to operate at the European UHF RFID band. In order to communicate the mobile phone with the RFID reader module, NFC technology has been considered. Thus, an NFC antenna, based on square coils, operating at 13.56 MHz has been also designed. Such antenna has been etched on the opposite side of the patch antenna. Overall dimensions of the prototype are 60 mm 100 mm, i.e., small enough to fit the dimensions of a mobile phone. As proof of concepts to evaluate the performance of the designed antennas, an UHF RFID reader module and a NFC reader module are tested. The measured read range reaches up to 1 m for some commercial tags. 100 mW of transmitted power. In [10], the UHF RFID functionality was achieved by modifying the mobile phone operating system. However, the read range was limited to 5 cm, even by using the maximum output power supplied by the mobile phone (0.25 W). Other proposed non-embedded solution consisted of
In this work, a passive ultra-high frequency radio-frequency identification UHF-RFID tag based on... more In this work, a passive ultra-high frequency radio-frequency identification UHF-RFID tag based on a 1.25 wavelengths thin dipole antenna is presented for the first time. The length of the antenna is properly chosen in order to maximize the tag read range, while maintaining a reasonable tag size and radiation pattern. The antenna is matched to the RFID chip by means of a very simple matching network based on a shunt inductance. A tag prototype, based on the Alien Higgs-3 chip, is designed and fabricated. The overall dimensions are 400 mmˆ14.6 mm, but the tag width for most of its length is delimited by the wire diameter (0.8 mm). The measured read range exhibits a maximum value of 17.5 m at the 902-928 MHz frequency band. This represents an important improvement over state-of-the-art passive UHF-RFID tags.
IEEE Transactions on Antennas and Propagation, 2016
An electrically small planar passive UHF-RFID tag based on an edge-coupled split ring resonator (... more An electrically small planar passive UHF-RFID tag based on an edge-coupled split ring resonator (EC-SRR) antenna is presented in this work. In order to explore the potentiality and limitations of the SRR antenna and to aid the tag design, an analytical study of the SRR radiation properties at its fundamental resonance is presented for the first time. Radiation resistance, efficiency, polarization, bandwidth and impedance matching with the RFID ASIC are treated in the study. Based on such analysis, the tag design process is presented, and a tag prototype of size 30 mm × 30 mm (λ 0 /11 × λ 0 /11) is designed to operate in the North-American UHF-RFID band (902−928 MHz) and manufactured. The measured read range is in good agreement with the simulation, and reaches 9.3 m at 911 MHz. The tag also features a mitigation of the blind spots, providing a minimum measured read range of 4.2 m.
IEEE Antennas and Wireless Propagation Letters, 2015
A technique for the suppression of the common-mode in differential (balanced) microstrip lines, b... more A technique for the suppression of the common-mode in differential (balanced) microstrip lines, based on electromagnetic bandgaps (EBGs), is presented in this paper. It is demonstrated that by periodically modulating the commonmode characteristic impedance of the line and simultaneously forcing the differential-mode impedance to be uniform (and equal to the reference impedance of the differential ports), the common-mode can be efficiently suppressed over a certain frequency band, whilst the line is transparent for the differential-mode. The main advantage of EBGs, as compared to other approaches for common-mode suppression in differential microstrip lines, is the fact that the ground plane is kept unaltered. Moreover, the design of the differential line is straightforward since the required level of common-mode suppression and bandwidth are given by simple approximate analytical expressions. As a design example, we report a 4-stage common-mode suppressed differential line with 68% fractional bandwidth for the common-mode stopband centered at 2.4GHz, and maximum common-mode rejection ratio (CMRR) of 19dB at that frequency. Furthermore, we have designed and fabricated a 6-stage double-tuned common-mode suppressed differential line in order to enhance the stopband bandwidth for the common mode around 2.4GHz.
New sub wavelength resonant particles are proposed. The resonant frequency of the particles is re... more New sub wavelength resonant particles are proposed. The resonant frequency of the particles is reduced by increasing the length of the resonators and increasing the coupling between resonators. Since this frequency reduction is equivalent to an area reduction, the structure can be used to achieve high compactness levels in Left Handed (LH) based circuits. As illustrative example an LH cell is implemented by using this new resonator.
IEEE Transactions on Microwave Theory and Techniques, 2015
This paper presents a novel approach for the implementation of balanced ultra-wideband (UWB) band... more This paper presents a novel approach for the implementation of balanced ultra-wideband (UWB) bandpass filters with common-mode noise suppression. To a first-order approximation, the differential-mode filter response is described by the canonical circuit model of a bandpass filter, i.e., a cascade of series-connected resonators alternating with shunt-connected parallel resonant tanks. Thus, the series branches of the balanced filter are implemented by means of inductive strips and patch capacitors, whereas the shunt sections are realized through mirrored stepped-impedance resonators (SIRs) and low-impedance (i.e., capacitive) short transmission-line sections. For the differential mode, the symmetry plane is a virtual ground, the wide strip sections of the SIRs are effectively grounded, and the SIRs behave as grounded inductors parallel connected to capacitors. However, for the common mode, where the symmetry plane is an open (magnetic wall), the SIRs act as shunt-connected series resonators, thus providing transmission zeros at their resonance frequencies. By properly tailoring the location of these transmission zeros, rejection of the common mode over the differential filter passband can be achieved. To illustrate the potential of the approach, an order-5 balanced bandpass filter covering the regulated band for UWB communications (3.1-10.6 GHz) is designed and fabricated. The filter exhibits common-mode rejection above 10 dB over the whole differential filter passband, with differential-mode insertion losses lower than 1.9 dB and return losses better than 10 dB. Since the proposed design approach is based on planar semi-lumped components, filter size is as small as 10.5 mm 7.6 mm.
IEEE Transactions on Microwave Theory and Techniques, 2014
This paper is focused on the automated and unattended optimization of a type of planar wideband b... more This paper is focused on the automated and unattended optimization of a type of planar wideband bandpass filters by means of aggressive space mapping (ASM). The considered filters are microstrip filters implemented through a combination of shunt connected stepped impedance resonators (SIRs) and grounded stubs coupled through admittance inverters. The most relevant and novel aspect of this paper is the fact that the filter layout is automatically generated from filter specifications, i.e., central frequency, fractional bandwidth, in-band ripple and order, without the need of any external aid to the design process. To achieve this layout generation, filter optimization has been divided into two independent ASM processes. The first one generates the filter schematic (circuit element values) providing the required specifications. This first iterative process is necessary since, due to the narrow band operation of the admittance inverters, the target specifications are achieved by compensating the effects of such narrow band operation. The purpose of the second ASM algorithm is to automatically generate the layout from the filter schematic resulting from the first ASM process. To validate the new two-step ASM optimization tool, two sets of filter specifications (inputs of the developed tool), are considered. The generated filter layouts exhibit frequency responses that satisfy the specifications, and are in excellent agreement with the responses of the schematics.
This paper proposes a dual-band power divider operating at GHz frequencies and implemented by mea... more This paper proposes a dual-band power divider operating at GHz frequencies and implemented by means of impedance transformers (also called inverters) based on lattice networks and transmission line sections. The dual-band functionality of the proposed device is achieved thanks to the composite right/left handed (CRLH) behavior of the impedance transformers, able to provide 90 o and +90 o phase shift at the first and second design frequencies, respectively, of the divider. By using such combination of transmission line sections and lattice networks, the characteristic impedance of the impedance transformers is roughly constant over wide bandwidths, with the results of broad operating bands. To demonstrate the possibilities of the approach, a prototype device is designed, fabricated and characterized.
2013 IEEE MTT-S International Microwave Symposium Digest (MTT), 2013
A novel strategy for the design of common-mode suppressed differential (or balanced) filters, bas... more A novel strategy for the design of common-mode suppressed differential (or balanced) filters, based on stepped impedance resonators (SIRs), is presented. The differential mode band pass response is achieved by coupling parallel LC resonators, implemented by a patch capacitance and a grounded inductance, through admittance inverters. Such inverters are implemented by means of 90 o transmission lines, whereas the grounded inductances are implemented by means of mirrored stepped impedance resonators (SIR). For the differential mode, the symmetry plane is a virtual ground, the wide strip section of the SIR is effectively grounded, and the SIR behaves as a shunt inductance. However, for the common mode, where the symmetry plane is an open (magnetic wall), the SIR is a shunt connected series resonator, providing a transmission zero, which can be used for the rejection of the common mode in the differential filter pass band. The equivalent circuit model of the proposed structure is validated through electromagnetic simulation and experimental data of order-3 and-5 Chebyshev differential bandpass filters. Moreover, guidelines for the design of balanced filters with wide bandwidths, including ultrawideband (UWB) bandpass filters, are provided.
This section presents the simulation and results of the parameter. Figure 2 shows the measured an... more This section presents the simulation and results of the parameter. Figure 2 shows the measured and simulated radiation patterns for the E-plane (y-z) and H-plane (x-y), at the frequencies 5.4 GHz. The radiation pattern in the H-plane is nearly omnidirectional and E-plane has the doughnut characteristic of a monopole antenna. Figure 3 shows the measured and simulated reflection coefficient versus frequency. There is acceptable agreement between simulated and measured results. Figure 4 shows a photograph of the fabricated prototype. The antenna is simulated using the commercial software package HFSS. The reflection coefficient is also measured using an Agilent 8757D Scalar Network Analyzer. Using a VSWR 2, the measured result shows that the antenna covers 4.83-6.25-GHz frequency ranges; thus, the impedance bandwidths are 23.4%. The frequency bands covered by this antenna are suitable for WLAN (5.15-5.67 GHz) and ITS (5.795-6.45 GHz) band. 4. CONCLUSIONS The printed dual ring loop antenna with dimensions of 36 Â 40 Â 1.52 mm 3 and operating frequency 4.83-6.25 GHz was proposed in this letter. The achieved bandwidth is 27.4%. The antenna offers acceptable reflection coefficient and radiation pattern characteristics, as evidenced through measurement and simulation. The designed antennas are expected to be compact, simple, and as such, to integrate well with other communication devices. This proposes antenna can be used for WLAN (5.15-5.67 GHz) communications and ITS (5.795-6.4 GHz) wireless applications.
... The authors are with GEMMA/CIMITEC, Departament d&#x2... more ... The authors are with GEMMA/CIMITEC, Departament d'Enginyeria Electrónica, Universitat Autónoma de Barcelona, 08193 Bellaterra, Barcelona, Spain (e-mail: [email protected]). Digital Object Identifier: 10.1109/JPROC.2011.2114870 Vol. 99, No. ...
Data in Figure 4 present the dependence of the magnetization with applied field for two orthogona... more Data in Figure 4 present the dependence of the magnetization with applied field for two orthogonal sample orientations. Significant changes were not observed for the saturation magnetization after a 90°sample rotation, while a reduction of the remanence at H ϭ 0 Oe was clearly observed. Such behavior suggested that a preferential magnetization axis was present in the samples, and it is probably related to a light collective orientation of acicular particles. 4. CONCLUSIONS In conclusion, cheap, lightweight, nonmetallic magnetic materials optically transparent in the visible spectral range can be obtained by thermal decomposition of iron(II) mercaptide dissolved in amorphous polystyrene. The thermolysis process performed in presence of air leaves to a nanosized magnetite phase (Fe 3 O 4) showing the characteristic acicular texture. The obtained nanocomposite material shows a ferromagnetic behavior and the resulting magnetic properties (e.g. remanence and magnetization saturation) improves with increasing of magnetite content. The magnetic properties anisotropically behave, probably because of a nonuniform distribution of the nanometric phase (particle concentration and orientation) inside the polymer matrix. The observed ferromagnetic behavior is related to the multi-domain structure of generated magnetite. bedded noble metal clusters by thermolysis of mercaptide dissolved in polymers, Polym Eng Sci, in press.
In this paper, microstrip lines magnetically coupled to splitring resonators (SRRs) are conquved ... more In this paper, microstrip lines magnetically coupled to splitring resonators (SRRs) are conquved to electromagnetic bundgup (EBG) nr,rrostrip lines in terns q/ their stop-heard penjbrnmrnce and dimensions. In bath types o/ trunsmis•siou lines, signal propagation is inhibited in it certain jequency bwuL For EBG microstrip lines, the central frequency of such a forbidden band is determined by the period of the structure, whereas in SRR-hased microstrip lines the position of the frequency gap depends on the quasi-static resonant frequency of the rings. The main relevant conrributiun of this paper is to provide a tuning procedure to control the gap width in SRR microstrip lines, and to show that by using SRRs, device dimensions ale much smaller than those required by EBGs in order to obtain similar stop-banal performance. This has been demonstrated by fill-wave electromagnetic simulations and experimentally verified from the characterization ql two fabricated microstrip lines: one with rectangular SRRs etched on the upper substrate side, and the other with a periodic perturbation cf'strip width. For similar rejection and 1-(;H,. gap width centered at 4.5 Gllz, it has been found that the SRR microstrip line is•,fve times shorter. In addition, no ripple is appreciable in the allowed band for the .SRR-hared structure, whereas due to dispersion, certain mismatch is expected in the EBG prototype. Due to the high-frequency selectivity, controllable gap width, and small dimensions, it is believed that SRR coupled to planar transmission lines can have an actual impact on the design of stop-band filters compatible with planar technology, and can be an alternative to present solutions based on distributed approaches or EBG. ® 2W5 Wiley Periodicals, Inc.
It is shown that radiofrequency micro-electromechanical-system (RF-MEMS) switches are useful to i... more It is shown that radiofrequency micro-electromechanical-system (RF-MEMS) switches are useful to implement electronically reconfigurable split ring resonators (SRRs). Three different combinations of cantilever-type ON/OFF capacitive switches with SRRs are studied for the design of tunable or switchable SRR-loaded metamaterial transmission lines. These structures are then applied to the design of reconfigurable band stop and band pass filters at the X-frequency band. Through electrostatic actuation of the switches, the resonance frequency of SRRs can be shifted and, as a result, filter bandwidth and/or central frequency can be digitally controlled. Good agreement between theory and experiment is achieved.
Journal of Electromagnetic Waves and Applications, 2003
In this work, we study the reflection properties of coplanar waveguides (CPW) periodically loaded... more In this work, we study the reflection properties of coplanar waveguides (CPW) periodically loaded with shunt connected capacitances and periodically perturbed by varying the slot width. These structures are of interest because the low pass frequency response with spurious frequency bands, inherent to the presence of capacitors, can be improved. This is achieved through the attenuation of frequency parasitics that is obtained by the introduction of slot width modulation. Both sinusoidal and square wave patterns are considered and the effects of the relative position of reactive elements with regard to the perturbation geometry is analysed. According to coupled
International Journal of RF and Microwave Computer-Aided Engineering, 2012
This article is a review of recent applications of split rings to the design of planar microwave ... more This article is a review of recent applications of split rings to the design of planar microwave circuits based on metamaterial concepts. The considered resonators, namely, split-ring resonators (SRRs), complementary SRRs (CSRRs), and their open counterparts (OSRRs and OCSRRs), are reviewed, and the equivalent circuit models of artificial lines based on such resonators, including parasitics, are presented and discussed. The second part of the article is devoted to highlight some recent applications of the considered resonators. This will include the design of dual-band components and wideband bandpass filters based on the combination of OSRRs and OCSRRs, the design of tunable components based on cantilever-type SRRs, and the design of CSRR-based differential (balanced) lines with common-mode suppression.
A new design approach for compact microstrip band-pass filter based on semi-lumped resonators are... more A new design approach for compact microstrip band-pass filter based on semi-lumped resonators are proposed. The resonators, which are coupled through quarter wavelength meander lines acting as admittance inverters, are shunt connected to the line. They consist of parallel combination of a grounded (inductive) stub and a narrow metallic strip followed by a capacitive patch to ground. With this topology, the necessary degree of flexibility to design narrow and broad-band-pass filters with compact dimensions and good out-of-band performance was obtained. Another key advantage of the devices, as compared to previous lumped or semi-lumped elementbased structures reported by the authors, is the absence of ground plane etching. To illustrate the potentiality of the proposed approach, a third-order (30% fractional bandwidth) and a nineth-order (35% fractional bandwidth) Chebyshev band-pass filters have been designed and fabricated. The measured frequency responses are very symmetric and exhibit low in-band losses as well as good out-of-band rejection up to approximately 3f o. Filter dimensions are as small as 0:40l  0:12l (third-order prototype) and 0:62l  0:16l (nineth-order prototype), l being the guided wavelength at f o. With these dimensions and performance, and the possibility to synthesise microstrip filters with controllable bandwidth over a wide margin, it is believed that the reported approach can be of actual interest for the design of planar filters at microwave frequencies.
IEEE Transactions on Microwave Theory and Techniques, 2006
In this paper, it is demonstrated that varactor-loaded split-ring resonators (VLSRRs) coupled to ... more In this paper, it is demonstrated that varactor-loaded split-ring resonators (VLSRRs) coupled to microstrip lines can lead to metamaterial transmission lines with tuning capability. Both negative permeability (0) and double (or left-handed) negative media have been designed and fabricated with tuning ranges as wide as 30%. The negative effective permeability is provided by the VLSRRs in a narrow band above their resonant frequency, which can be bias controlled by virtue of the presence of diode varactors. To achieve a negative effective permittivity in the left-handed structure, metallic vias emulating shunt inductances are periodically placed between the conductor strip and the ground plane. The lumped-element equivalent-circuit models of the designed structures have been derived. It has been found that these models provide a good qualitative description of device performance. Since the VLSRR microstrip line and the line loaded with both VLSRRs and vias exhibit stopband and bandpass behavior, respectively, the ideas presented in this study can be applied to the design of narrowband tunable frequency-selective structures with compact dimensions. This is the first time that a tunable left-handed transmission line, based on SRRs, is proposed.
IEEE Transactions on Microwave Theory and Techniques, 2007
In this paper, we discuss in detail the transmission characteristics of composite right/left-hand... more In this paper, we discuss in detail the transmission characteristics of composite right/left-handed transmission lines based on complementary split-rings resonators. Specifically, the necessary conditions to obtain a continuous transition between the left-and right-handed bands (balanced case) are pointed out. It is found that very wide bands can be obtained by balancing the line. The application of this technique to the design of very wideband and compact filters is illustrated by means of two examples. One of them is based on the hybrid approach, where a microstrip line is loaded with complementary split-rings resonators, series gaps, and grounded stubs; the other one is a bandpass filter, also based on a balanced line, but in this case, by using only complementary split-rings resonators and series gaps (purely resonant-type approach). As will be seen, very small dimensions and good performance are obtained. The proposed filters are useful for ultra-wideband systems.
IEEE Transactions on Microwave Theory and Techniques, 2009
This paper is focused on the application of open split ring resonators (OSRRs) and their dual cou... more This paper is focused on the application of open split ring resonators (OSRRs) and their dual counterparts, open complementary split ring resonators (OCSRRs), to the synthesis of composite right/left-handed transmission lines, that is, artificial lines exhibiting backward wave propagation at low frequencies and forward wave propagation at high frequencies. Due to the small dimensions of these resonators, the resulting lines are very compact. Several artificial lines, with different electrical characteristics and topologies, are reported as illustrative examples. It is shown that these artificial lines can be applied to the synthesis of dual-band components and bandpass filters, and two prototype device examples are designed and fabricated in coplanar waveguide technology: a dual-band impedance inverter applied to a dual-band power divider, and an order-3 wide-band bandpass filter. Finally, it is also demonstrated that OSRRs and OCSRRs can be combined for the synthesis of band pass filters in microstrip technology. Since OSRRs and OCSRRs are described by means of series and shunt resonant tanks, respectively, and they are electrically small, their potential to the design of semi lumped planar microwave devices is very high. Index Terms-Artificial transmission lines, dual-band components, metamaterials, microwave filters, open complementary split ring resonators (OCSRRs), open split rings resonators (OSRRs). I. INTRODUCTION A RTIFICIAL transmission lines based on metamaterial concepts, that is, metamaterial transmission lines, have been a subject of growing interest in recent years. Such lines are artificial structures consisting on a host propagating medium loaded with reactive elements. Special efforts have been dedicated to the synthesis of artificial lines exhibiting backward wave transmission at low frequencies and forward wave propagation at high frequencies. These composite right/left-handed lines have been implemented in microstrip [1], [2], coplanar
A small size and low profile antenna has been developed in order to provide any mobile phone with... more A small size and low profile antenna has been developed in order to provide any mobile phone with UHF RFID reader functionality. For that purpose, a patch antenna topology has been chosen on account of the mobile phone battery, which exhibits an electromagnetic behavior similar to a metal plane. The low profile patch antenna has been designed to operate at the European UHF RFID band. In order to communicate the mobile phone with the RFID reader module, NFC technology has been considered. Thus, an NFC antenna, based on square coils, operating at 13.56 MHz has been also designed. Such antenna has been etched on the opposite side of the patch antenna. Overall dimensions of the prototype are 60 mm 100 mm, i.e., small enough to fit the dimensions of a mobile phone. As proof of concepts to evaluate the performance of the designed antennas, an UHF RFID reader module and a NFC reader module are tested. The measured read range reaches up to 1 m for some commercial tags. 100 mW of transmitted power. In [10], the UHF RFID functionality was achieved by modifying the mobile phone operating system. However, the read range was limited to 5 cm, even by using the maximum output power supplied by the mobile phone (0.25 W). Other proposed non-embedded solution consisted of
In this work, a passive ultra-high frequency radio-frequency identification UHF-RFID tag based on... more In this work, a passive ultra-high frequency radio-frequency identification UHF-RFID tag based on a 1.25 wavelengths thin dipole antenna is presented for the first time. The length of the antenna is properly chosen in order to maximize the tag read range, while maintaining a reasonable tag size and radiation pattern. The antenna is matched to the RFID chip by means of a very simple matching network based on a shunt inductance. A tag prototype, based on the Alien Higgs-3 chip, is designed and fabricated. The overall dimensions are 400 mmˆ14.6 mm, but the tag width for most of its length is delimited by the wire diameter (0.8 mm). The measured read range exhibits a maximum value of 17.5 m at the 902-928 MHz frequency band. This represents an important improvement over state-of-the-art passive UHF-RFID tags.
IEEE Transactions on Antennas and Propagation, 2016
An electrically small planar passive UHF-RFID tag based on an edge-coupled split ring resonator (... more An electrically small planar passive UHF-RFID tag based on an edge-coupled split ring resonator (EC-SRR) antenna is presented in this work. In order to explore the potentiality and limitations of the SRR antenna and to aid the tag design, an analytical study of the SRR radiation properties at its fundamental resonance is presented for the first time. Radiation resistance, efficiency, polarization, bandwidth and impedance matching with the RFID ASIC are treated in the study. Based on such analysis, the tag design process is presented, and a tag prototype of size 30 mm × 30 mm (λ 0 /11 × λ 0 /11) is designed to operate in the North-American UHF-RFID band (902−928 MHz) and manufactured. The measured read range is in good agreement with the simulation, and reaches 9.3 m at 911 MHz. The tag also features a mitigation of the blind spots, providing a minimum measured read range of 4.2 m.
IEEE Antennas and Wireless Propagation Letters, 2015
A technique for the suppression of the common-mode in differential (balanced) microstrip lines, b... more A technique for the suppression of the common-mode in differential (balanced) microstrip lines, based on electromagnetic bandgaps (EBGs), is presented in this paper. It is demonstrated that by periodically modulating the commonmode characteristic impedance of the line and simultaneously forcing the differential-mode impedance to be uniform (and equal to the reference impedance of the differential ports), the common-mode can be efficiently suppressed over a certain frequency band, whilst the line is transparent for the differential-mode. The main advantage of EBGs, as compared to other approaches for common-mode suppression in differential microstrip lines, is the fact that the ground plane is kept unaltered. Moreover, the design of the differential line is straightforward since the required level of common-mode suppression and bandwidth are given by simple approximate analytical expressions. As a design example, we report a 4-stage common-mode suppressed differential line with 68% fractional bandwidth for the common-mode stopband centered at 2.4GHz, and maximum common-mode rejection ratio (CMRR) of 19dB at that frequency. Furthermore, we have designed and fabricated a 6-stage double-tuned common-mode suppressed differential line in order to enhance the stopband bandwidth for the common mode around 2.4GHz.
New sub wavelength resonant particles are proposed. The resonant frequency of the particles is re... more New sub wavelength resonant particles are proposed. The resonant frequency of the particles is reduced by increasing the length of the resonators and increasing the coupling between resonators. Since this frequency reduction is equivalent to an area reduction, the structure can be used to achieve high compactness levels in Left Handed (LH) based circuits. As illustrative example an LH cell is implemented by using this new resonator.
IEEE Transactions on Microwave Theory and Techniques, 2015
This paper presents a novel approach for the implementation of balanced ultra-wideband (UWB) band... more This paper presents a novel approach for the implementation of balanced ultra-wideband (UWB) bandpass filters with common-mode noise suppression. To a first-order approximation, the differential-mode filter response is described by the canonical circuit model of a bandpass filter, i.e., a cascade of series-connected resonators alternating with shunt-connected parallel resonant tanks. Thus, the series branches of the balanced filter are implemented by means of inductive strips and patch capacitors, whereas the shunt sections are realized through mirrored stepped-impedance resonators (SIRs) and low-impedance (i.e., capacitive) short transmission-line sections. For the differential mode, the symmetry plane is a virtual ground, the wide strip sections of the SIRs are effectively grounded, and the SIRs behave as grounded inductors parallel connected to capacitors. However, for the common mode, where the symmetry plane is an open (magnetic wall), the SIRs act as shunt-connected series resonators, thus providing transmission zeros at their resonance frequencies. By properly tailoring the location of these transmission zeros, rejection of the common mode over the differential filter passband can be achieved. To illustrate the potential of the approach, an order-5 balanced bandpass filter covering the regulated band for UWB communications (3.1-10.6 GHz) is designed and fabricated. The filter exhibits common-mode rejection above 10 dB over the whole differential filter passband, with differential-mode insertion losses lower than 1.9 dB and return losses better than 10 dB. Since the proposed design approach is based on planar semi-lumped components, filter size is as small as 10.5 mm 7.6 mm.
IEEE Transactions on Microwave Theory and Techniques, 2014
This paper is focused on the automated and unattended optimization of a type of planar wideband b... more This paper is focused on the automated and unattended optimization of a type of planar wideband bandpass filters by means of aggressive space mapping (ASM). The considered filters are microstrip filters implemented through a combination of shunt connected stepped impedance resonators (SIRs) and grounded stubs coupled through admittance inverters. The most relevant and novel aspect of this paper is the fact that the filter layout is automatically generated from filter specifications, i.e., central frequency, fractional bandwidth, in-band ripple and order, without the need of any external aid to the design process. To achieve this layout generation, filter optimization has been divided into two independent ASM processes. The first one generates the filter schematic (circuit element values) providing the required specifications. This first iterative process is necessary since, due to the narrow band operation of the admittance inverters, the target specifications are achieved by compensating the effects of such narrow band operation. The purpose of the second ASM algorithm is to automatically generate the layout from the filter schematic resulting from the first ASM process. To validate the new two-step ASM optimization tool, two sets of filter specifications (inputs of the developed tool), are considered. The generated filter layouts exhibit frequency responses that satisfy the specifications, and are in excellent agreement with the responses of the schematics.
This paper proposes a dual-band power divider operating at GHz frequencies and implemented by mea... more This paper proposes a dual-band power divider operating at GHz frequencies and implemented by means of impedance transformers (also called inverters) based on lattice networks and transmission line sections. The dual-band functionality of the proposed device is achieved thanks to the composite right/left handed (CRLH) behavior of the impedance transformers, able to provide 90 o and +90 o phase shift at the first and second design frequencies, respectively, of the divider. By using such combination of transmission line sections and lattice networks, the characteristic impedance of the impedance transformers is roughly constant over wide bandwidths, with the results of broad operating bands. To demonstrate the possibilities of the approach, a prototype device is designed, fabricated and characterized.
2013 IEEE MTT-S International Microwave Symposium Digest (MTT), 2013
A novel strategy for the design of common-mode suppressed differential (or balanced) filters, bas... more A novel strategy for the design of common-mode suppressed differential (or balanced) filters, based on stepped impedance resonators (SIRs), is presented. The differential mode band pass response is achieved by coupling parallel LC resonators, implemented by a patch capacitance and a grounded inductance, through admittance inverters. Such inverters are implemented by means of 90 o transmission lines, whereas the grounded inductances are implemented by means of mirrored stepped impedance resonators (SIR). For the differential mode, the symmetry plane is a virtual ground, the wide strip section of the SIR is effectively grounded, and the SIR behaves as a shunt inductance. However, for the common mode, where the symmetry plane is an open (magnetic wall), the SIR is a shunt connected series resonator, providing a transmission zero, which can be used for the rejection of the common mode in the differential filter pass band. The equivalent circuit model of the proposed structure is validated through electromagnetic simulation and experimental data of order-3 and-5 Chebyshev differential bandpass filters. Moreover, guidelines for the design of balanced filters with wide bandwidths, including ultrawideband (UWB) bandpass filters, are provided.
This section presents the simulation and results of the parameter. Figure 2 shows the measured an... more This section presents the simulation and results of the parameter. Figure 2 shows the measured and simulated radiation patterns for the E-plane (y-z) and H-plane (x-y), at the frequencies 5.4 GHz. The radiation pattern in the H-plane is nearly omnidirectional and E-plane has the doughnut characteristic of a monopole antenna. Figure 3 shows the measured and simulated reflection coefficient versus frequency. There is acceptable agreement between simulated and measured results. Figure 4 shows a photograph of the fabricated prototype. The antenna is simulated using the commercial software package HFSS. The reflection coefficient is also measured using an Agilent 8757D Scalar Network Analyzer. Using a VSWR 2, the measured result shows that the antenna covers 4.83-6.25-GHz frequency ranges; thus, the impedance bandwidths are 23.4%. The frequency bands covered by this antenna are suitable for WLAN (5.15-5.67 GHz) and ITS (5.795-6.45 GHz) band. 4. CONCLUSIONS The printed dual ring loop antenna with dimensions of 36 Â 40 Â 1.52 mm 3 and operating frequency 4.83-6.25 GHz was proposed in this letter. The achieved bandwidth is 27.4%. The antenna offers acceptable reflection coefficient and radiation pattern characteristics, as evidenced through measurement and simulation. The designed antennas are expected to be compact, simple, and as such, to integrate well with other communication devices. This proposes antenna can be used for WLAN (5.15-5.67 GHz) communications and ITS (5.795-6.4 GHz) wireless applications.
... The authors are with GEMMA/CIMITEC, Departament d&#x2... more ... The authors are with GEMMA/CIMITEC, Departament d'Enginyeria Electrónica, Universitat Autónoma de Barcelona, 08193 Bellaterra, Barcelona, Spain (e-mail: [email protected]). Digital Object Identifier: 10.1109/JPROC.2011.2114870 Vol. 99, No. ...
Data in Figure 4 present the dependence of the magnetization with applied field for two orthogona... more Data in Figure 4 present the dependence of the magnetization with applied field for two orthogonal sample orientations. Significant changes were not observed for the saturation magnetization after a 90°sample rotation, while a reduction of the remanence at H ϭ 0 Oe was clearly observed. Such behavior suggested that a preferential magnetization axis was present in the samples, and it is probably related to a light collective orientation of acicular particles. 4. CONCLUSIONS In conclusion, cheap, lightweight, nonmetallic magnetic materials optically transparent in the visible spectral range can be obtained by thermal decomposition of iron(II) mercaptide dissolved in amorphous polystyrene. The thermolysis process performed in presence of air leaves to a nanosized magnetite phase (Fe 3 O 4) showing the characteristic acicular texture. The obtained nanocomposite material shows a ferromagnetic behavior and the resulting magnetic properties (e.g. remanence and magnetization saturation) improves with increasing of magnetite content. The magnetic properties anisotropically behave, probably because of a nonuniform distribution of the nanometric phase (particle concentration and orientation) inside the polymer matrix. The observed ferromagnetic behavior is related to the multi-domain structure of generated magnetite. bedded noble metal clusters by thermolysis of mercaptide dissolved in polymers, Polym Eng Sci, in press.
In this paper, microstrip lines magnetically coupled to splitring resonators (SRRs) are conquved ... more In this paper, microstrip lines magnetically coupled to splitring resonators (SRRs) are conquved to electromagnetic bundgup (EBG) nr,rrostrip lines in terns q/ their stop-heard penjbrnmrnce and dimensions. In bath types o/ trunsmis•siou lines, signal propagation is inhibited in it certain jequency bwuL For EBG microstrip lines, the central frequency of such a forbidden band is determined by the period of the structure, whereas in SRR-hased microstrip lines the position of the frequency gap depends on the quasi-static resonant frequency of the rings. The main relevant conrributiun of this paper is to provide a tuning procedure to control the gap width in SRR microstrip lines, and to show that by using SRRs, device dimensions ale much smaller than those required by EBGs in order to obtain similar stop-banal performance. This has been demonstrated by fill-wave electromagnetic simulations and experimentally verified from the characterization ql two fabricated microstrip lines: one with rectangular SRRs etched on the upper substrate side, and the other with a periodic perturbation cf'strip width. For similar rejection and 1-(;H,. gap width centered at 4.5 Gllz, it has been found that the SRR microstrip line is•,fve times shorter. In addition, no ripple is appreciable in the allowed band for the .SRR-hared structure, whereas due to dispersion, certain mismatch is expected in the EBG prototype. Due to the high-frequency selectivity, controllable gap width, and small dimensions, it is believed that SRR coupled to planar transmission lines can have an actual impact on the design of stop-band filters compatible with planar technology, and can be an alternative to present solutions based on distributed approaches or EBG. ® 2W5 Wiley Periodicals, Inc.
It is shown that radiofrequency micro-electromechanical-system (RF-MEMS) switches are useful to i... more It is shown that radiofrequency micro-electromechanical-system (RF-MEMS) switches are useful to implement electronically reconfigurable split ring resonators (SRRs). Three different combinations of cantilever-type ON/OFF capacitive switches with SRRs are studied for the design of tunable or switchable SRR-loaded metamaterial transmission lines. These structures are then applied to the design of reconfigurable band stop and band pass filters at the X-frequency band. Through electrostatic actuation of the switches, the resonance frequency of SRRs can be shifted and, as a result, filter bandwidth and/or central frequency can be digitally controlled. Good agreement between theory and experiment is achieved.
Journal of Electromagnetic Waves and Applications, 2003
In this work, we study the reflection properties of coplanar waveguides (CPW) periodically loaded... more In this work, we study the reflection properties of coplanar waveguides (CPW) periodically loaded with shunt connected capacitances and periodically perturbed by varying the slot width. These structures are of interest because the low pass frequency response with spurious frequency bands, inherent to the presence of capacitors, can be improved. This is achieved through the attenuation of frequency parasitics that is obtained by the introduction of slot width modulation. Both sinusoidal and square wave patterns are considered and the effects of the relative position of reactive elements with regard to the perturbation geometry is analysed. According to coupled
International Journal of RF and Microwave Computer-Aided Engineering, 2012
This article is a review of recent applications of split rings to the design of planar microwave ... more This article is a review of recent applications of split rings to the design of planar microwave circuits based on metamaterial concepts. The considered resonators, namely, split-ring resonators (SRRs), complementary SRRs (CSRRs), and their open counterparts (OSRRs and OCSRRs), are reviewed, and the equivalent circuit models of artificial lines based on such resonators, including parasitics, are presented and discussed. The second part of the article is devoted to highlight some recent applications of the considered resonators. This will include the design of dual-band components and wideband bandpass filters based on the combination of OSRRs and OCSRRs, the design of tunable components based on cantilever-type SRRs, and the design of CSRR-based differential (balanced) lines with common-mode suppression.
A new design approach for compact microstrip band-pass filter based on semi-lumped resonators are... more A new design approach for compact microstrip band-pass filter based on semi-lumped resonators are proposed. The resonators, which are coupled through quarter wavelength meander lines acting as admittance inverters, are shunt connected to the line. They consist of parallel combination of a grounded (inductive) stub and a narrow metallic strip followed by a capacitive patch to ground. With this topology, the necessary degree of flexibility to design narrow and broad-band-pass filters with compact dimensions and good out-of-band performance was obtained. Another key advantage of the devices, as compared to previous lumped or semi-lumped elementbased structures reported by the authors, is the absence of ground plane etching. To illustrate the potentiality of the proposed approach, a third-order (30% fractional bandwidth) and a nineth-order (35% fractional bandwidth) Chebyshev band-pass filters have been designed and fabricated. The measured frequency responses are very symmetric and exhibit low in-band losses as well as good out-of-band rejection up to approximately 3f o. Filter dimensions are as small as 0:40l  0:12l (third-order prototype) and 0:62l  0:16l (nineth-order prototype), l being the guided wavelength at f o. With these dimensions and performance, and the possibility to synthesise microstrip filters with controllable bandwidth over a wide margin, it is believed that the reported approach can be of actual interest for the design of planar filters at microwave frequencies.
IEEE Transactions on Microwave Theory and Techniques, 2006
In this paper, it is demonstrated that varactor-loaded split-ring resonators (VLSRRs) coupled to ... more In this paper, it is demonstrated that varactor-loaded split-ring resonators (VLSRRs) coupled to microstrip lines can lead to metamaterial transmission lines with tuning capability. Both negative permeability (0) and double (or left-handed) negative media have been designed and fabricated with tuning ranges as wide as 30%. The negative effective permeability is provided by the VLSRRs in a narrow band above their resonant frequency, which can be bias controlled by virtue of the presence of diode varactors. To achieve a negative effective permittivity in the left-handed structure, metallic vias emulating shunt inductances are periodically placed between the conductor strip and the ground plane. The lumped-element equivalent-circuit models of the designed structures have been derived. It has been found that these models provide a good qualitative description of device performance. Since the VLSRR microstrip line and the line loaded with both VLSRRs and vias exhibit stopband and bandpass behavior, respectively, the ideas presented in this study can be applied to the design of narrowband tunable frequency-selective structures with compact dimensions. This is the first time that a tunable left-handed transmission line, based on SRRs, is proposed.
IEEE Transactions on Microwave Theory and Techniques, 2007
In this paper, we discuss in detail the transmission characteristics of composite right/left-hand... more In this paper, we discuss in detail the transmission characteristics of composite right/left-handed transmission lines based on complementary split-rings resonators. Specifically, the necessary conditions to obtain a continuous transition between the left-and right-handed bands (balanced case) are pointed out. It is found that very wide bands can be obtained by balancing the line. The application of this technique to the design of very wideband and compact filters is illustrated by means of two examples. One of them is based on the hybrid approach, where a microstrip line is loaded with complementary split-rings resonators, series gaps, and grounded stubs; the other one is a bandpass filter, also based on a balanced line, but in this case, by using only complementary split-rings resonators and series gaps (purely resonant-type approach). As will be seen, very small dimensions and good performance are obtained. The proposed filters are useful for ultra-wideband systems.
IEEE Transactions on Microwave Theory and Techniques, 2009
This paper is focused on the application of open split ring resonators (OSRRs) and their dual cou... more This paper is focused on the application of open split ring resonators (OSRRs) and their dual counterparts, open complementary split ring resonators (OCSRRs), to the synthesis of composite right/left-handed transmission lines, that is, artificial lines exhibiting backward wave propagation at low frequencies and forward wave propagation at high frequencies. Due to the small dimensions of these resonators, the resulting lines are very compact. Several artificial lines, with different electrical characteristics and topologies, are reported as illustrative examples. It is shown that these artificial lines can be applied to the synthesis of dual-band components and bandpass filters, and two prototype device examples are designed and fabricated in coplanar waveguide technology: a dual-band impedance inverter applied to a dual-band power divider, and an order-3 wide-band bandpass filter. Finally, it is also demonstrated that OSRRs and OCSRRs can be combined for the synthesis of band pass filters in microstrip technology. Since OSRRs and OCSRRs are described by means of series and shunt resonant tanks, respectively, and they are electrically small, their potential to the design of semi lumped planar microwave devices is very high. Index Terms-Artificial transmission lines, dual-band components, metamaterials, microwave filters, open complementary split ring resonators (OCSRRs), open split rings resonators (OSRRs). I. INTRODUCTION A RTIFICIAL transmission lines based on metamaterial concepts, that is, metamaterial transmission lines, have been a subject of growing interest in recent years. Such lines are artificial structures consisting on a host propagating medium loaded with reactive elements. Special efforts have been dedicated to the synthesis of artificial lines exhibiting backward wave transmission at low frequencies and forward wave propagation at high frequencies. These composite right/left-handed lines have been implemented in microstrip [1], [2], coplanar
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Papers by Jordi Bonache