IEEE GLOBECOM 2008 - 2008 IEEE Global Telecommunications Conference, 2008
In this paper, we propose a novel Multiple-Input Multiple-Output (MIMO) wireless communication sy... more In this paper, we propose a novel Multiple-Input Multiple-Output (MIMO) wireless communication system employing reconfigurable PIXEL antennas at the receiver. We design a Space-Time-State Block Coding scheme for the PIXEL-based reconfigurable MIMO system and propose optimal and ad hoc state-selection algorithms that achieve maximum diversity gains. Moreover, we prove that in state-selection schemes, contrary to antenna selection, there is no benefit in selecting more than one state. Furthermore, we discuss the gains of state-selection over the state-switching scheme proposed in [1]. Finally, we evaluate the theoretical findings through simulations. These simulations are conducted using a realistic channel model, that takes into account the radio-electric characteristics (radiation pattern, gain, efficiency, etc.) of the PIXEL antennas.
IEEE Antennas and Propagation Society International Symposium. Digest. Held in conjunction with: USNC/CNC/URSI North American Radio Sci. Meeting (Cat. No.03CH37450)
A single-arm circular spiral antenna has been investigated to get adaptable circular polarization... more A single-arm circular spiral antenna has been investigated to get adaptable circular polarization and tilt beam. Circular spiral is printed on a finite size dielectric substrate (ε r =3.27) backed by a finite sizeconducting plane. Circular spiral radiates Right Handed Circular Polarization (RHCP) in its inner feed and Left Hand Circular Polarization (LHCP) in its outer feed in one antenna element. Circular spiral has an axial beam (L1=1.64λ g ) in the z-axis and two-tilted beams (L2=3.25λ g , L3=5.55λ g ) of RHCP in inner feed and LHCP in outer feed at 10GHz, where L is a horizontal arm length. The frequency bandwidth for a 3-dB axial ratio criterion is about 25% in both inner and outer feed at L1=1.64λ g .
2000 IEEE MTT-S International Microwave Symposium Digest (Cat. No.00CH37017)
This paper is focused on the creation of an efficient electromagnetic model of MEMS switches whic... more This paper is focused on the creation of an efficient electromagnetic model of MEMS switches which operates at microwave frequencies. The switches are first characterized using a full wave analysis based on finite element method aiming to extract the S-parameters of the switches for different geometrical dimensions. From the S-parameter data base, a scalable lumped circuit model is extracted to allow easy implementation of the switch model into available microwave CAD software. The simulated results are compared with published measured data as validation of our model.
Proceedings of the 16th International Symposium on Power Semiconductor Devices & IC's
Summary form only given. A multidisciplinary research effort focusing on indoor communication sys... more Summary form only given. A multidisciplinary research effort focusing on indoor communication systems, motivated by the fact that the solutions to next-generation communications systems lie in a multidisciplinary research approach formed by electromagnetics, micro systems, and information theory, is presented. To this end, we first study the interrelationships between a given coding/decoding structure and multiple antenna elements used to transmit
2012 6th European Conference on Antennas and Propagation (EUCAP), 2012
ABSTRACT In this paper, mm-wave band scattering measurements are performed and imaging reconstruc... more ABSTRACT In this paper, mm-wave band scattering measurements are performed and imaging reconstructions obtained using a 2-D Scatterer Mapping Technique based on a Multi-Frequency Bi-Focusing operator (MF-BF). The measured data matrix is also processed to obtain its eigenvalues and eigenvectors. A relation between the eigenvalues and the number of scatterers and the eigenvectors and the scatterers spatial localization is obtained.
IEEE Antennas and Propagation Society Symposium, 2004., 2004
This paper presents an investigation for adaptive parameters of multi-antenna schemes for its use... more This paper presents an investigation for adaptive parameters of multi-antenna schemes for its use in future reconfigurable MIMO systems. The study puts a special emphasis in linking the concept of channel diversity, either in the spatial or polarization domain, with the type of polarization being used both at the transmitter (TX) and receiver (RX), and the level of multipath provided by the channel in the vertical or horizontal direction, with respect to the propagation plane. It has been found that NLOS indoor channels are very sensitive to type of signal diversity being employed and the type of polarization and component of the multipath being used.
IEEE Antennas and Propagation Society Symposium, 2004., 2004
This paper presents an investigation for adaptive parameters of multi-antenna schemes for its use... more This paper presents an investigation for adaptive parameters of multi-antenna schemes for its use in future reconfigurable MIMO systems. The study puts a special emphasis in linking the concept of channel diversity, either in the spatial or polarization domain, with the type of polarization being used both at the transmitter (TX) and receiver (RX), and the level of multipath provided by the channel in the vertical or horizontal direction, with respect to the propagation plane. It has been found that NLOS indoor channels are very sensitive to type of signal diversity being employed and the type of polarization and component of the multipath being used.
IEEE Antennas and Propagation Society International Symposium (IEEE Cat. No.02CH37313)
A small size dual-band antenna for integration with 5-6 GHz RF/Wireless communication systems is ... more A small size dual-band antenna for integration with 5-6 GHz RF/Wireless communication systems is presented. The size and structure of the antenna are designed for integration with a RF printed circuit board of a given size (thickness=1.36mm=0.045λ), metallization structure (4-level of metalization) and material properties (FR4, ε r =3.78, loss tangent=0.01). It is capacitively fed by a coplanar waveguide (CPW) to allow easier integration with active and passive circuit components. The procedure used to develop this new antenna structure is described. Computational results showing the antenna's impedance behavior and radiation characteristics are given.
2005 IEEE Antennas and Propagation Society International Symposium
The objectives of designing meander line antenna are miniaturization of antenna and application o... more The objectives of designing meander line antenna are miniaturization of antenna and application of spatial power combining to make circular polarization. A linearly polarized planar antenna is proposed. Helical meander line is printed on both sides of the antenna substrate. It is appropriate to reduce the size of low resonant frequency antennas. The meander line antennas with opposite polarization directions can spatially combine differential outputs of a power amplifier without combiner. Circular polarization antenna is built by orthogonally placing and combining the linear polarization of the antennas. This concept can be applied to design a power amplifier, which is combined with the outputs of power limited CMOS amplifiers.
2009 IEEE International Workshop on Antenna Technology, 2009
A step-by-step approach to build a very low cost automated measurement setup for MIMO systems is ... more A step-by-step approach to build a very low cost automated measurement setup for MIMO systems is presented in this paper. The price of the system can be lowered to $500 by reusing specific hardware elements. The performance of the setup is also evaluated with results obtained from an indoor environment measurement campaign conducted at UCI Radiofrequency laboratory.
The 8th European Conference on Antennas and Propagation (EuCAP 2014), 2014
In this paper we analyze the benefit of using phased arrays as the receiving antennas of indoor l... more In this paper we analyze the benefit of using phased arrays as the receiving antennas of indoor location systems. A 60 GHz code division multiple access carrier-based ultra-wide band positioning system for the simultaneous location of diverse markers is considered. The positioning error in an indoor environment is assessed when omnidirectional antennas are used at the receiving sensors and when they are substituted by beamforming antennas. Results show that beamforming systems can effectively mitigate the multipath effects and achieve positioning accuracies close to those achievable in free space scenarios. The performance of omnidirectional systems is severely degraded by multipath and multiple access interference.
2011 XXXth URSI General Assembly and Scientific Symposium, 2011
This paper investigates the performance evaluation of a reconfigurable multimode pixeled antenna ... more This paper investigates the performance evaluation of a reconfigurable multimode pixeled antenna in wireless communication systems employing antenna pattern/polarization diversity techniques. Simulations have been conducted using an indoor clustered MIMO channel model.
This paper is focused on the creation of an efficient electromagnetic model of MEMS switches whic... more This paper is focused on the creation of an efficient electromagnetic model of MEMS switches which operates at microwave frequencies. The switches are first characterized using a full wave analysis based on a finite element method to extract the S-parameters of the switches for different geometrical dimensions. From the S-parameter database, a scalable lumped circuit model is extracted to allow easy implementation of the switch model into commercial microwave CAD software. The lumped circuit model results are compared with published measured data as validation of our model.
2011 IEEE International Symposium on Antennas and Propagation (APSURSI), 2011
ABSTRACT In this paper, a printed grid array antenna on a low cost packaging substrate is present... more ABSTRACT In this paper, a printed grid array antenna on a low cost packaging substrate is presented. Simulation and measurement results of the antenna return losses and radiation patterns are provided. Simulations show that the antenna is matched on the frequency band from 57 to 64GHz and has a broadside gain of over 11dB all over the band. Measurement results show that the antenna performance is shifted 2GHz upwards in frequency but is not degraded. The difference between the simulated and the real substrate permittivity has been identified as the source of the frequency response shift.
2013 IEEE Antennas and Propagation Society International Symposium (APSURSI), 2013
ABSTRACT In this paper, a grid antenna with beam selection capability is presented. The antenna c... more ABSTRACT In this paper, a grid antenna with beam selection capability is presented. The antenna covers the entire 60GHz band, from 57 to 64 GHz, and has a gain greater than 11dB over the whole band. With only 3 different feeding points, fed by in-phase and quadrature signals, the antenna can generate 5 beams between -14° to 14° from broadside in steps of 7°. The antenna, fabricated on a low cost packaging substrate, satisfies the requirements of low cost and small size for mass production and is a good candidate for 60GHz LOS communication systems.
Proceedings of SPIE - The International Society for Optical Engineering, 2004
describes micro-fabricated RF-MEMS capacitive switches on microwave printed circuit boards (PCB) ... more describes micro-fabricated RF-MEMS capacitive switches on microwave printed circuit boards (PCB) with high dielectric materials. Copper oxide is used as its dielectric layer. The use of copper oxide has a couple of advantages. First, high relative dielectric constant of copper oxide ( r 18.1) provides higher down position capacitance, which can re-position the isolation valley at the lower frequency. Second, the fabrication step related to the growth copper oxide layers becomes relatively straightforward as opposed to the deposition of our previous dielectric layer, silicon nitride ( r 7.4). To improve the switching performance by achieving a desired high capacitance ratio, the down state capacitance must be as high as possible. The down state capacitance and capacitance ratio of copper oxide is found to be higher than silicon nitride in the case of the same overlapping area, between membrane and CPW signal line. A switch with copper oxide is shown to have a lower isolation valley frequency as opposed to that with silicon nitride layer. Switches with lower isolation valley frequencies have potentials for commercial applications. The copper oxide is selectively grown on the surface copper electrode by patterning the photoresist and then exposing the chip to oxygen plasma. The oxygen plasma is achieved by RF power of 370 watts with oxygen pressure at 0.45 torr. The fabrication process for copper oxide is relatively straightforward than silicon nitride deposition and etching using Plasma Enhanced Chemical Vapor Deposition (PECVD) and Reactive Ion Etching (RIE).
2008 IEEE Antennas and Propagation Society International Symposium, 2008
In this work, we present a bandwidth enhanced solution based on a different and more flexible rep... more In this work, we present a bandwidth enhanced solution based on a different and more flexible repeater architecture which uses MEMS-reconfigurable loaded parasitics and an aperture coupling feeding mechanism. The proposed gap-filler can be smartly reconfigured in real-time to optimize its performance (matching and isolation level and bandwidth) in the presence of a changing surrounding environment.
2010 International Workshop on Antenna Technology (iWAT), 2010
ABSTRACT In this paper we investigate a new approach in optimizing the number of switches in reco... more ABSTRACT In this paper we investigate a new approach in optimizing the number of switches in reconfigurable antennas designed for MIMO (Multiple Input Multiple Output) applications. Reducing the number of switches in reconfigurable antenna structures can lead to cost effective designs and reduce losses. Here a new optimization technique based on graph theory is introduced. A specific example is presented and analyzed to prove the validity of the new approach.
Next-generation cellular networks deployment will require systems with broadband capabilities in ... more Next-generation cellular networks deployment will require systems with broadband capabilities in high-mobility environments. Data rates up to 100 Mbits/s and above, high spectral efficiencies and stronger fading mitigation have to be achieved. Technologies needed to obtain these specifications, include multibeam antenna systems, wideband transceivers, and robust and efficient space-time coding. In this paper we present a new reconfigurable miniature antenna architecture, compatible with the packaging constraints, able to change its working frequency, polarization, or radiation pattern in order to get, single broadband or dualband behavior, for a single widebeam or multibeam diversity configuration.
IEEE GLOBECOM 2008 - 2008 IEEE Global Telecommunications Conference, 2008
In this paper, we propose a novel Multiple-Input Multiple-Output (MIMO) wireless communication sy... more In this paper, we propose a novel Multiple-Input Multiple-Output (MIMO) wireless communication system employing reconfigurable PIXEL antennas at the receiver. We design a Space-Time-State Block Coding scheme for the PIXEL-based reconfigurable MIMO system and propose optimal and ad hoc state-selection algorithms that achieve maximum diversity gains. Moreover, we prove that in state-selection schemes, contrary to antenna selection, there is no benefit in selecting more than one state. Furthermore, we discuss the gains of state-selection over the state-switching scheme proposed in [1]. Finally, we evaluate the theoretical findings through simulations. These simulations are conducted using a realistic channel model, that takes into account the radio-electric characteristics (radiation pattern, gain, efficiency, etc.) of the PIXEL antennas.
IEEE Antennas and Propagation Society International Symposium. Digest. Held in conjunction with: USNC/CNC/URSI North American Radio Sci. Meeting (Cat. No.03CH37450)
A single-arm circular spiral antenna has been investigated to get adaptable circular polarization... more A single-arm circular spiral antenna has been investigated to get adaptable circular polarization and tilt beam. Circular spiral is printed on a finite size dielectric substrate (ε r =3.27) backed by a finite sizeconducting plane. Circular spiral radiates Right Handed Circular Polarization (RHCP) in its inner feed and Left Hand Circular Polarization (LHCP) in its outer feed in one antenna element. Circular spiral has an axial beam (L1=1.64λ g ) in the z-axis and two-tilted beams (L2=3.25λ g , L3=5.55λ g ) of RHCP in inner feed and LHCP in outer feed at 10GHz, where L is a horizontal arm length. The frequency bandwidth for a 3-dB axial ratio criterion is about 25% in both inner and outer feed at L1=1.64λ g .
2000 IEEE MTT-S International Microwave Symposium Digest (Cat. No.00CH37017)
This paper is focused on the creation of an efficient electromagnetic model of MEMS switches whic... more This paper is focused on the creation of an efficient electromagnetic model of MEMS switches which operates at microwave frequencies. The switches are first characterized using a full wave analysis based on finite element method aiming to extract the S-parameters of the switches for different geometrical dimensions. From the S-parameter data base, a scalable lumped circuit model is extracted to allow easy implementation of the switch model into available microwave CAD software. The simulated results are compared with published measured data as validation of our model.
Proceedings of the 16th International Symposium on Power Semiconductor Devices & IC's
Summary form only given. A multidisciplinary research effort focusing on indoor communication sys... more Summary form only given. A multidisciplinary research effort focusing on indoor communication systems, motivated by the fact that the solutions to next-generation communications systems lie in a multidisciplinary research approach formed by electromagnetics, micro systems, and information theory, is presented. To this end, we first study the interrelationships between a given coding/decoding structure and multiple antenna elements used to transmit
2012 6th European Conference on Antennas and Propagation (EUCAP), 2012
ABSTRACT In this paper, mm-wave band scattering measurements are performed and imaging reconstruc... more ABSTRACT In this paper, mm-wave band scattering measurements are performed and imaging reconstructions obtained using a 2-D Scatterer Mapping Technique based on a Multi-Frequency Bi-Focusing operator (MF-BF). The measured data matrix is also processed to obtain its eigenvalues and eigenvectors. A relation between the eigenvalues and the number of scatterers and the eigenvectors and the scatterers spatial localization is obtained.
IEEE Antennas and Propagation Society Symposium, 2004., 2004
This paper presents an investigation for adaptive parameters of multi-antenna schemes for its use... more This paper presents an investigation for adaptive parameters of multi-antenna schemes for its use in future reconfigurable MIMO systems. The study puts a special emphasis in linking the concept of channel diversity, either in the spatial or polarization domain, with the type of polarization being used both at the transmitter (TX) and receiver (RX), and the level of multipath provided by the channel in the vertical or horizontal direction, with respect to the propagation plane. It has been found that NLOS indoor channels are very sensitive to type of signal diversity being employed and the type of polarization and component of the multipath being used.
IEEE Antennas and Propagation Society Symposium, 2004., 2004
This paper presents an investigation for adaptive parameters of multi-antenna schemes for its use... more This paper presents an investigation for adaptive parameters of multi-antenna schemes for its use in future reconfigurable MIMO systems. The study puts a special emphasis in linking the concept of channel diversity, either in the spatial or polarization domain, with the type of polarization being used both at the transmitter (TX) and receiver (RX), and the level of multipath provided by the channel in the vertical or horizontal direction, with respect to the propagation plane. It has been found that NLOS indoor channels are very sensitive to type of signal diversity being employed and the type of polarization and component of the multipath being used.
IEEE Antennas and Propagation Society International Symposium (IEEE Cat. No.02CH37313)
A small size dual-band antenna for integration with 5-6 GHz RF/Wireless communication systems is ... more A small size dual-band antenna for integration with 5-6 GHz RF/Wireless communication systems is presented. The size and structure of the antenna are designed for integration with a RF printed circuit board of a given size (thickness=1.36mm=0.045λ), metallization structure (4-level of metalization) and material properties (FR4, ε r =3.78, loss tangent=0.01). It is capacitively fed by a coplanar waveguide (CPW) to allow easier integration with active and passive circuit components. The procedure used to develop this new antenna structure is described. Computational results showing the antenna's impedance behavior and radiation characteristics are given.
2005 IEEE Antennas and Propagation Society International Symposium
The objectives of designing meander line antenna are miniaturization of antenna and application o... more The objectives of designing meander line antenna are miniaturization of antenna and application of spatial power combining to make circular polarization. A linearly polarized planar antenna is proposed. Helical meander line is printed on both sides of the antenna substrate. It is appropriate to reduce the size of low resonant frequency antennas. The meander line antennas with opposite polarization directions can spatially combine differential outputs of a power amplifier without combiner. Circular polarization antenna is built by orthogonally placing and combining the linear polarization of the antennas. This concept can be applied to design a power amplifier, which is combined with the outputs of power limited CMOS amplifiers.
2009 IEEE International Workshop on Antenna Technology, 2009
A step-by-step approach to build a very low cost automated measurement setup for MIMO systems is ... more A step-by-step approach to build a very low cost automated measurement setup for MIMO systems is presented in this paper. The price of the system can be lowered to $500 by reusing specific hardware elements. The performance of the setup is also evaluated with results obtained from an indoor environment measurement campaign conducted at UCI Radiofrequency laboratory.
The 8th European Conference on Antennas and Propagation (EuCAP 2014), 2014
In this paper we analyze the benefit of using phased arrays as the receiving antennas of indoor l... more In this paper we analyze the benefit of using phased arrays as the receiving antennas of indoor location systems. A 60 GHz code division multiple access carrier-based ultra-wide band positioning system for the simultaneous location of diverse markers is considered. The positioning error in an indoor environment is assessed when omnidirectional antennas are used at the receiving sensors and when they are substituted by beamforming antennas. Results show that beamforming systems can effectively mitigate the multipath effects and achieve positioning accuracies close to those achievable in free space scenarios. The performance of omnidirectional systems is severely degraded by multipath and multiple access interference.
2011 XXXth URSI General Assembly and Scientific Symposium, 2011
This paper investigates the performance evaluation of a reconfigurable multimode pixeled antenna ... more This paper investigates the performance evaluation of a reconfigurable multimode pixeled antenna in wireless communication systems employing antenna pattern/polarization diversity techniques. Simulations have been conducted using an indoor clustered MIMO channel model.
This paper is focused on the creation of an efficient electromagnetic model of MEMS switches whic... more This paper is focused on the creation of an efficient electromagnetic model of MEMS switches which operates at microwave frequencies. The switches are first characterized using a full wave analysis based on a finite element method to extract the S-parameters of the switches for different geometrical dimensions. From the S-parameter database, a scalable lumped circuit model is extracted to allow easy implementation of the switch model into commercial microwave CAD software. The lumped circuit model results are compared with published measured data as validation of our model.
2011 IEEE International Symposium on Antennas and Propagation (APSURSI), 2011
ABSTRACT In this paper, a printed grid array antenna on a low cost packaging substrate is present... more ABSTRACT In this paper, a printed grid array antenna on a low cost packaging substrate is presented. Simulation and measurement results of the antenna return losses and radiation patterns are provided. Simulations show that the antenna is matched on the frequency band from 57 to 64GHz and has a broadside gain of over 11dB all over the band. Measurement results show that the antenna performance is shifted 2GHz upwards in frequency but is not degraded. The difference between the simulated and the real substrate permittivity has been identified as the source of the frequency response shift.
2013 IEEE Antennas and Propagation Society International Symposium (APSURSI), 2013
ABSTRACT In this paper, a grid antenna with beam selection capability is presented. The antenna c... more ABSTRACT In this paper, a grid antenna with beam selection capability is presented. The antenna covers the entire 60GHz band, from 57 to 64 GHz, and has a gain greater than 11dB over the whole band. With only 3 different feeding points, fed by in-phase and quadrature signals, the antenna can generate 5 beams between -14° to 14° from broadside in steps of 7°. The antenna, fabricated on a low cost packaging substrate, satisfies the requirements of low cost and small size for mass production and is a good candidate for 60GHz LOS communication systems.
Proceedings of SPIE - The International Society for Optical Engineering, 2004
describes micro-fabricated RF-MEMS capacitive switches on microwave printed circuit boards (PCB) ... more describes micro-fabricated RF-MEMS capacitive switches on microwave printed circuit boards (PCB) with high dielectric materials. Copper oxide is used as its dielectric layer. The use of copper oxide has a couple of advantages. First, high relative dielectric constant of copper oxide ( r 18.1) provides higher down position capacitance, which can re-position the isolation valley at the lower frequency. Second, the fabrication step related to the growth copper oxide layers becomes relatively straightforward as opposed to the deposition of our previous dielectric layer, silicon nitride ( r 7.4). To improve the switching performance by achieving a desired high capacitance ratio, the down state capacitance must be as high as possible. The down state capacitance and capacitance ratio of copper oxide is found to be higher than silicon nitride in the case of the same overlapping area, between membrane and CPW signal line. A switch with copper oxide is shown to have a lower isolation valley frequency as opposed to that with silicon nitride layer. Switches with lower isolation valley frequencies have potentials for commercial applications. The copper oxide is selectively grown on the surface copper electrode by patterning the photoresist and then exposing the chip to oxygen plasma. The oxygen plasma is achieved by RF power of 370 watts with oxygen pressure at 0.45 torr. The fabrication process for copper oxide is relatively straightforward than silicon nitride deposition and etching using Plasma Enhanced Chemical Vapor Deposition (PECVD) and Reactive Ion Etching (RIE).
2008 IEEE Antennas and Propagation Society International Symposium, 2008
In this work, we present a bandwidth enhanced solution based on a different and more flexible rep... more In this work, we present a bandwidth enhanced solution based on a different and more flexible repeater architecture which uses MEMS-reconfigurable loaded parasitics and an aperture coupling feeding mechanism. The proposed gap-filler can be smartly reconfigured in real-time to optimize its performance (matching and isolation level and bandwidth) in the presence of a changing surrounding environment.
2010 International Workshop on Antenna Technology (iWAT), 2010
ABSTRACT In this paper we investigate a new approach in optimizing the number of switches in reco... more ABSTRACT In this paper we investigate a new approach in optimizing the number of switches in reconfigurable antennas designed for MIMO (Multiple Input Multiple Output) applications. Reducing the number of switches in reconfigurable antenna structures can lead to cost effective designs and reduce losses. Here a new optimization technique based on graph theory is introduced. A specific example is presented and analyzed to prove the validity of the new approach.
Next-generation cellular networks deployment will require systems with broadband capabilities in ... more Next-generation cellular networks deployment will require systems with broadband capabilities in high-mobility environments. Data rates up to 100 Mbits/s and above, high spectral efficiencies and stronger fading mitigation have to be achieved. Technologies needed to obtain these specifications, include multibeam antenna systems, wideband transceivers, and robust and efficient space-time coding. In this paper we present a new reconfigurable miniature antenna architecture, compatible with the packaging constraints, able to change its working frequency, polarization, or radiation pattern in order to get, single broadband or dualband behavior, for a single widebeam or multibeam diversity configuration.
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Papers by Franco Flaviis