In this paper, we present a broadband quasi-Yagi antenna. Good impedance matching is obtained by using parasitic elements. The antenna has been designed and successfully measured. Experimental results show that the 10...In this paper, we present a broadband quasi-Yagi antenna. Good impedance matching is obtained by using parasitic elements. The antenna has been designed and successfully measured. Experimental results show that the 10 dB return loss bandwidth of this antenna is 50% operating from 2.3 GHz to 3.8 GHz. We obtain very flat gain (around 5 dB) over the entire bandwidth. For the design and optimization of antennas, we use HFSS CAD software from ANSOFT.展开更多
In this paper, we describe 2 kinds of printed dipole arrays and compare the performances of these arrays in term of reflexion coefficient, radiation pattern and dimensions. It is interesting to design array in order t...In this paper, we describe 2 kinds of printed dipole arrays and compare the performances of these arrays in term of reflexion coefficient, radiation pattern and dimensions. It is interesting to design array in order to obtain better performances in term of omnidirectional radiation pattern in comparison with single element. We choose this elementary source in order to obtain compact array with good performances. These antenna arrays are designed to have omnidirectional radiation pattern with horizontal polarization. We present an application dedicated to compact base station in the last section.展开更多
<div style="text-align:justify;"> The number of connected objects and therefore of IoT devices that invade our daily lives is growing exponentially. These objects are based on electronics in the form o...<div style="text-align:justify;"> The number of connected objects and therefore of IoT devices that invade our daily lives is growing exponentially. These objects are based on electronics in the form of elementary components, circuits and hybrid and complex integrated systems. Electronics must therefore respond to an exponential growth in the number of circuits, components per circuit, data transmitted, stored and processed in data centers. As a corollary, the energy consumed by operators, servers and users follows the same law of growth. In the coming years, the main challenges will be to slow down these exponential growths by improving the design and architecture of components, circuits and systems for processing and transmitting information. These challenges require the acquisition of skills based on knowledge and know-how and an increase in the pool of future competent and innovative players. This approach is part of the strategy led by the national academic training network which, by pooling the skills of trainers and technological platforms at the French level, aims to meet the needs of companies within the framework of a Recovery Plan for the Electronic Sector. After a presentation of the context and the consequences on the technical challenges, and after several approaches proposed, the actions carried out by the national network of microelectronics are detailed and illustrated with several examples of realizations and results. </div>展开更多
This paper describes our contribution in the ANR (Agence Nationale de la Recherche) project called GELOCOM (GEo-LOCalisation de telephOnes Mobiles) managed by the THALES Communications company, dedicated to the emerge...This paper describes our contribution in the ANR (Agence Nationale de la Recherche) project called GELOCOM (GEo-LOCalisation de telephOnes Mobiles) managed by the THALES Communications company, dedicated to the emergency localization of cellular phones. This contribution takes place in the field of antennas, with the development of broad-band systems: a circular array of six elements with separated outputs for the receiving part. In this paper, we present the design and the characterization of broad-band double ellipse array antenna. This special structure is chosen in order to obtain a good omnidirectional radiation pattern, enhance the gain and maximize the V/H polarization ratio. In comparison with the already existing antenna systems in the wireless market for similar purposes, the proposed antenna has considerably shown better performance which makes it competitive among other antenna models. For the design and optimization of antennas, we use CST MWS software. The antennas have been designed and successfully measured.展开更多
In this paper, an antenna with reconfigurable band notches, for cognitive radio applications, is proposed. The antenna can be operated as ultra wideband, and is reconfigurable in terms of the ability to select a notch...In this paper, an antenna with reconfigurable band notches, for cognitive radio applications, is proposed. The antenna can be operated as ultra wideband, and is reconfigurable in terms of the ability to select a notched band in the SRR resonant frequency. The reconfigurable band notches are induced using a band-stop filter based on split-ring resonators (SRRs), and are controlled using electronic switches mounted over the SRRs. For this sake, the design of the band-stop filter is proposed. A prototype of filter is fabricated and measured. The incorporation of a band-stop filter, into a wideband antenna, is then looked into. The proposed antenna is designed and simulated using Ansoft HFSS. A prototype of the antenna is fabricated and measured. A good analogy between simulated and measured results is obtained.展开更多
The circular phased antenna array is commonly used for generating waves bearing Orbital Angular Momentum (OAM) in the radio frequency band, but it achieves a relatively low directivity. To overcome this drawback, we p...The circular phased antenna array is commonly used for generating waves bearing Orbital Angular Momentum (OAM) in the radio frequency band, but it achieves a relatively low directivity. To overcome this drawback, we present here a method to improve the directivity of an OAM circular phased antenna array by embedding it inside a Fabry-Perot cavity. The Fabry-Perot cavity contains three main parts: a partially reflecting surface (PRS), an air cavity and a ground plane. Simulation data show that the directivity of this new OAM antenna achieves an improvement of 8.2 dB over the original array. A prototype is realized and characterized. The simulated and measured characteristics are in good agreement.展开更多
Combination of multiple-input multiple-output (MIMO) with orthogonal frequency division multiplexing (OFDM) has become a promising candidate for high performance wireless communications. However one major disadvantage...Combination of multiple-input multiple-output (MIMO) with orthogonal frequency division multiplexing (OFDM) has become a promising candidate for high performance wireless communications. However one major disadvantage of MIMO-OFDM systems lies in a prohibitively large peak-to-average power ratio (PAPR) of the transmitted signal on each antenna. In this paper we extend from SISO to MIMO systems a method based on allocating dedicated subcarriers for PAPR mitigation. These subcarriers are located on unused subcarriers of OFDM spectrum under the assumption they all fall under the power mask. This is originally implemented with a SOCP optimization algorithm applied before space time coding scheme. This jointly mitigates PAPR on each MIMO branch scheme. This approach does not degrade the bit-error-rate (BER) and the data bit rate and no side information (SI) transmission is required. Simulation results are presented in the IEEE 802.16 WiMAX standard contexts: an Alamouti space time code with two transmitted antennas and 256 OFDM subcarriers are considered where 56 of which are unused and allocated for PAPR reduction. PAPR gains up to 7dB are obtained depending on mean power increase limitation. Moreover, with a spectrum mask constraint, this method is standard compliant.展开更多
A hardware simulator reproduces the behavior of the radio propagation channel, thus making it possible to test “on table” the mobile radio equipments. The simulator can be used for LTE and WLAN 802.11ac applications...A hardware simulator reproduces the behavior of the radio propagation channel, thus making it possible to test “on table” the mobile radio equipments. The simulator can be used for LTE and WLAN 802.11ac applications, in indoor and outdoor environments. In this paper, the input signals parameters and the relative power of the impulse responses are related to the relative error and SNR of the output signals. After analyzing the influence of these parameters on the output error and SNR, an algorithm based on an Auto-Scale Factor (ASF) is analyzed in details to improve the precision of the output signals of the hardware simulator digital block architecture. Moreover, the circuit needed for the validation of this algorithm has been introduced, verified and realized. It is shown that this solution increases the output SNR if the relative powers of the impulse responses are attenuated. The new architecture of the digital block is presented and implemented on a Xilinx Virtex-IV FPGA. The occupation on the FPGA and the accuracy of the architecture are analyzed.展开更多
Nonlinear PAPR reducers, such as clipping and companding techniques, are some simple methods used to reduce the Peak-to-Average Power Ratio (PAPR). In this paper, assuming that the baseband OFDM signal is characterize...Nonlinear PAPR reducers, such as clipping and companding techniques, are some simple methods used to reduce the Peak-to-Average Power Ratio (PAPR). In this paper, assuming that the baseband OFDM signal is characterized as a band-limited complex Gaussian process, we investigate the PAPR distribution of an OFDM signal when it is passed through a nonlinear PAPR reducer. The obtained PAPR distribution depends on the nonlinear function which characterizes the PAPR reducer. Later in this paper, we apply the obtained PAPR distribution in the clipping case. The comparisons made between the proposed distribution and that obtained thanks to computer simulations show good agreement.展开更多
This paper presents the design and the experimental characterization of a new multi-band antenna consisting of three folded monopoles dedicated to mobile communication systems. The originality of this paper is to get ...This paper presents the design and the experimental characterization of a new multi-band antenna consisting of three folded monopoles dedicated to mobile communication systems. The originality of this paper is to get the PMR (Professional or Private Mobile Radio) band with the GSM (Global System for Mobile Communications), DCS (Digital Cellular System) and UMTS (Universal Mobile Telecommunications System) bands. The main lobe of the antenna radiates in the zenith direction with a linear polarization over all bands. It is interesting to design the proposed antenna in order to obtain better performances in terms of directive radiation pattern (especially in the PMR band) in comparison with the already existing antenna systems in the wireless market for similar purposes. The prototype was studied with the software CST-MWS (Micro wave studio 2012). The antenna has been designed and successfully measured.展开更多
In this paper, we propose a new design procedure for printed dipole array antennas. Applications of these arrays are devoted to wireless communication systems, mainly base stations and beam steerable antennas. All the...In this paper, we propose a new design procedure for printed dipole array antennas. Applications of these arrays are devoted to wireless communication systems, mainly base stations and beam steerable antennas. All the designs have been developed at the frequency of 3 GHz. This structure is chosen in order to enhance the gain and minimize the backside radiations of an antenna array with a very simple feeding.展开更多
This Letter introduces the design and simulation of a microstrip-line-based electro-optic （EO） polymer optical phase modulator （PM） that is further enhanced by the addition of photonic crystal （PhC） structures t...This Letter introduces the design and simulation of a microstrip-line-based electro-optic （EO） polymer optical phase modulator （PM） that is further enhanced by the addition of photonic crystal （PhC） structures that are in close proximity to the optical core. The slow-wave PhC structure is designed for two different material configurations and placed in the modulator as a superstrate to the optical core; simulation results are depicted for both 1D and 2D PhC structures. The PM characteristics are modeled using a combination of the finite element method and the optical beam propagation method in both the RF and optical domains, respectively. The phase-shift simulation results show a factor of 1.7 increase in an effective EO coefficient （120 pm/V） while maintaining a broadband bandwidth of 40 GHz.展开更多
Vanadium nitride （VN） was deposited by DC-sputtering on a vertically aligned carbon nanotube （CNTs） template for the purpose of nano-structuration. This led to the fabrication of hierarchically composite electrode...Vanadium nitride （VN） was deposited by DC-sputtering on a vertically aligned carbon nanotube （CNTs） template for the purpose of nano-structuration. This led to the fabrication of hierarchically composite electrodes consisting of porous and nanostructured VN grown on vertically aligned CNTs in a nano-treelike configuration for micro-supercapacitor application. The electrodes show excellent performance with an areal capacitance as high as 37.5 mF cm^-2 at a scan rate of 2 mV s^-1 in a 0.5 M K2504 mild electrolyte solution. Furthermore, the capacitance decay was only 15% after 20,000 consecutive cycles. Moreover, the capacitance was found to increase with VN deposit thickness. The X-ray photoelectron spectroscopy analyses of the electrodes before and after cycling suggest that the oxide layers that form at the VN surface is the responsible for the redox energy storage in this material. Such electrodes can compete with other transition metal nitride based electrodes for micro-supercapacitors.展开更多
基金The National Natural Science Foundation of China(No.81272501)the National Basic Research Program of China(973Program)(No.2011CB707904)Taishan Scholars Program of Shandong Province,China(No.ts20120505)
文摘In this paper, we present a broadband quasi-Yagi antenna. Good impedance matching is obtained by using parasitic elements. The antenna has been designed and successfully measured. Experimental results show that the 10 dB return loss bandwidth of this antenna is 50% operating from 2.3 GHz to 3.8 GHz. We obtain very flat gain (around 5 dB) over the entire bandwidth. For the design and optimization of antennas, we use HFSS CAD software from ANSOFT.
文摘In this paper, we describe 2 kinds of printed dipole arrays and compare the performances of these arrays in term of reflexion coefficient, radiation pattern and dimensions. It is interesting to design array in order to obtain better performances in term of omnidirectional radiation pattern in comparison with single element. We choose this elementary source in order to obtain compact array with good performances. These antenna arrays are designed to have omnidirectional radiation pattern with horizontal polarization. We present an application dedicated to compact base station in the last section.
文摘<div style="text-align:justify;"> The number of connected objects and therefore of IoT devices that invade our daily lives is growing exponentially. These objects are based on electronics in the form of elementary components, circuits and hybrid and complex integrated systems. Electronics must therefore respond to an exponential growth in the number of circuits, components per circuit, data transmitted, stored and processed in data centers. As a corollary, the energy consumed by operators, servers and users follows the same law of growth. In the coming years, the main challenges will be to slow down these exponential growths by improving the design and architecture of components, circuits and systems for processing and transmitting information. These challenges require the acquisition of skills based on knowledge and know-how and an increase in the pool of future competent and innovative players. This approach is part of the strategy led by the national academic training network which, by pooling the skills of trainers and technological platforms at the French level, aims to meet the needs of companies within the framework of a Recovery Plan for the Electronic Sector. After a presentation of the context and the consequences on the technical challenges, and after several approaches proposed, the actions carried out by the national network of microelectronics are detailed and illustrated with several examples of realizations and results. </div>
文摘This paper describes our contribution in the ANR (Agence Nationale de la Recherche) project called GELOCOM (GEo-LOCalisation de telephOnes Mobiles) managed by the THALES Communications company, dedicated to the emergency localization of cellular phones. This contribution takes place in the field of antennas, with the development of broad-band systems: a circular array of six elements with separated outputs for the receiving part. In this paper, we present the design and the characterization of broad-band double ellipse array antenna. This special structure is chosen in order to obtain a good omnidirectional radiation pattern, enhance the gain and maximize the V/H polarization ratio. In comparison with the already existing antenna systems in the wireless market for similar purposes, the proposed antenna has considerably shown better performance which makes it competitive among other antenna models. For the design and optimization of antennas, we use CST MWS software. The antennas have been designed and successfully measured.
文摘In this paper, an antenna with reconfigurable band notches, for cognitive radio applications, is proposed. The antenna can be operated as ultra wideband, and is reconfigurable in terms of the ability to select a notched band in the SRR resonant frequency. The reconfigurable band notches are induced using a band-stop filter based on split-ring resonators (SRRs), and are controlled using electronic switches mounted over the SRRs. For this sake, the design of the band-stop filter is proposed. A prototype of filter is fabricated and measured. The incorporation of a band-stop filter, into a wideband antenna, is then looked into. The proposed antenna is designed and simulated using Ansoft HFSS. A prototype of the antenna is fabricated and measured. A good analogy between simulated and measured results is obtained.
文摘The circular phased antenna array is commonly used for generating waves bearing Orbital Angular Momentum (OAM) in the radio frequency band, but it achieves a relatively low directivity. To overcome this drawback, we present here a method to improve the directivity of an OAM circular phased antenna array by embedding it inside a Fabry-Perot cavity. The Fabry-Perot cavity contains three main parts: a partially reflecting surface (PRS), an air cavity and a ground plane. Simulation data show that the directivity of this new OAM antenna achieves an improvement of 8.2 dB over the original array. A prototype is realized and characterized. The simulated and measured characteristics are in good agreement.
文摘Combination of multiple-input multiple-output (MIMO) with orthogonal frequency division multiplexing (OFDM) has become a promising candidate for high performance wireless communications. However one major disadvantage of MIMO-OFDM systems lies in a prohibitively large peak-to-average power ratio (PAPR) of the transmitted signal on each antenna. In this paper we extend from SISO to MIMO systems a method based on allocating dedicated subcarriers for PAPR mitigation. These subcarriers are located on unused subcarriers of OFDM spectrum under the assumption they all fall under the power mask. This is originally implemented with a SOCP optimization algorithm applied before space time coding scheme. This jointly mitigates PAPR on each MIMO branch scheme. This approach does not degrade the bit-error-rate (BER) and the data bit rate and no side information (SI) transmission is required. Simulation results are presented in the IEEE 802.16 WiMAX standard contexts: an Alamouti space time code with two transmitted antennas and 256 OFDM subcarriers are considered where 56 of which are unused and allocated for PAPR reduction. PAPR gains up to 7dB are obtained depending on mean power increase limitation. Moreover, with a spectrum mask constraint, this method is standard compliant.
文摘A hardware simulator reproduces the behavior of the radio propagation channel, thus making it possible to test “on table” the mobile radio equipments. The simulator can be used for LTE and WLAN 802.11ac applications, in indoor and outdoor environments. In this paper, the input signals parameters and the relative power of the impulse responses are related to the relative error and SNR of the output signals. After analyzing the influence of these parameters on the output error and SNR, an algorithm based on an Auto-Scale Factor (ASF) is analyzed in details to improve the precision of the output signals of the hardware simulator digital block architecture. Moreover, the circuit needed for the validation of this algorithm has been introduced, verified and realized. It is shown that this solution increases the output SNR if the relative powers of the impulse responses are attenuated. The new architecture of the digital block is presented and implemented on a Xilinx Virtex-IV FPGA. The occupation on the FPGA and the accuracy of the architecture are analyzed.
文摘Nonlinear PAPR reducers, such as clipping and companding techniques, are some simple methods used to reduce the Peak-to-Average Power Ratio (PAPR). In this paper, assuming that the baseband OFDM signal is characterized as a band-limited complex Gaussian process, we investigate the PAPR distribution of an OFDM signal when it is passed through a nonlinear PAPR reducer. The obtained PAPR distribution depends on the nonlinear function which characterizes the PAPR reducer. Later in this paper, we apply the obtained PAPR distribution in the clipping case. The comparisons made between the proposed distribution and that obtained thanks to computer simulations show good agreement.
文摘This paper presents the design and the experimental characterization of a new multi-band antenna consisting of three folded monopoles dedicated to mobile communication systems. The originality of this paper is to get the PMR (Professional or Private Mobile Radio) band with the GSM (Global System for Mobile Communications), DCS (Digital Cellular System) and UMTS (Universal Mobile Telecommunications System) bands. The main lobe of the antenna radiates in the zenith direction with a linear polarization over all bands. It is interesting to design the proposed antenna in order to obtain better performances in terms of directive radiation pattern (especially in the PMR band) in comparison with the already existing antenna systems in the wireless market for similar purposes. The prototype was studied with the software CST-MWS (Micro wave studio 2012). The antenna has been designed and successfully measured.
文摘In this paper, we propose a new design procedure for printed dipole array antennas. Applications of these arrays are devoted to wireless communication systems, mainly base stations and beam steerable antennas. All the designs have been developed at the frequency of 3 GHz. This structure is chosen in order to enhance the gain and minimize the backside radiations of an antenna array with a very simple feeding.
文摘This Letter introduces the design and simulation of a microstrip-line-based electro-optic （EO） polymer optical phase modulator （PM） that is further enhanced by the addition of photonic crystal （PhC） structures that are in close proximity to the optical core. The slow-wave PhC structure is designed for two different material configurations and placed in the modulator as a superstrate to the optical core; simulation results are depicted for both 1D and 2D PhC structures. The PM characteristics are modeled using a combination of the finite element method and the optical beam propagation method in both the RF and optical domains, respectively. The phase-shift simulation results show a factor of 1.7 increase in an effective EO coefficient （120 pm/V） while maintaining a broadband bandwidth of 40 GHz.
基金the Deanship of Scientific Research at King Saud University KSA for its funding of this research through the Research Group(Project No.RGP-283)
文摘Vanadium nitride （VN） was deposited by DC-sputtering on a vertically aligned carbon nanotube （CNTs） template for the purpose of nano-structuration. This led to the fabrication of hierarchically composite electrodes consisting of porous and nanostructured VN grown on vertically aligned CNTs in a nano-treelike configuration for micro-supercapacitor application. The electrodes show excellent performance with an areal capacitance as high as 37.5 mF cm^-2 at a scan rate of 2 mV s^-1 in a 0.5 M K2504 mild electrolyte solution. Furthermore, the capacitance decay was only 15% after 20,000 consecutive cycles. Moreover, the capacitance was found to increase with VN deposit thickness. The X-ray photoelectron spectroscopy analyses of the electrodes before and after cycling suggest that the oxide layers that form at the VN surface is the responsible for the redox energy storage in this material. Such electrodes can compete with other transition metal nitride based electrodes for micro-supercapacitors.
