M. Salazar-palma - Academia.edu (original) (raw)

Papers by M. Salazar-palma

Use of the Output Energy Filter in Multiantenna Systems for Adaptive Estimation

Physics of Multiantenna Systems and Broadband Processing, 2007

2005 IEEE Antennas and Propagation Society International Symposium

In this paper polarization adaptivity on transmit has been used to enhance the received signals d... more In this paper polarization adaptivity on transmit has been used to enhance the received signals directed to a pre-selected receiver in a near-field multi-input multi-output (MIMO) environment. The objective here is to select a set of weights on the transmitting antennas adapted to individual receivers based on the principles of reciprocity. Using the polarization properties, when the number of receiving antennas is greater than the number of transmitting antennas, the transmitted signal may be directed more to a particular receiver location while simultaneously minimizing the reception signal strength at other receivers. Numerical simulations have been made to illustrate the novelty of the proposed approach.

Solving large complex problems using a higher-order basis: parallel in-core and out-of-core integral-equation solvers

IEEE Antennas and Propagation Magazine, 2008

Abstract The future of computational electromagnetics is changing drastically with the new genera... more Abstract The future of computational electromagnetics is changing drastically with the new generation of computer chips, which are multi-cored instead of single-cored. Previously, advancements in chip technology meant an increase in clock speed, which was typically a ...

Predicting the starting distance of the far field

2016 IEEE International Symposium on Antennas and Propagation (APSURSI), 2016

The far field of an antenna is generally considered to be the region where the outgoing wavefront... more The far field of an antenna is generally considered to be the region where the outgoing wavefront is planar and the antenna radiation pattern has a polar variation and is independent of the distance from the antenna. Hence, to generate a locally plane wave in the far field the radial component of the electric field must be negligible compared to the transverse component. Also, the ratio of the electric and the magnetic far fields should equal the intrinsic impedance of the medium. These two requirements must hold in all angular directions from the antenna. The radial and the transverse components of the fields are space dependent so to determine the starting distance of the far field we need to examine the simultaneous satisfaction of these two properties for all θ and φ angular directions, where θ is the angle measured from z-axis and φ is the angle measured from the x-axis. The objective of this paper can be summarized in three points: First, this paper intends to illustrate that 2D2/λ formula, where D is the maximum dimension of the antenna and λ is the operating wavelength, is not universally valid, it is only valid for antennas where D ≫ λ. Second, this paper intends to compute a more specific constraint so instead of D ≫ λ we compute a threshold for D after which the 2D2/λ formula applies. Third, this paper intends to properly interpret D in the formula 2D2/λ when the antenna is operating over an imperfect ground plane. In this paper, we do not use 2D2/λ for antennas operating over an imperfect ground instead we use a formula which depends on the transmitting and receiving antenna's heights over the air-Earth interface.

A hands-on approach for engineering students and practitioners to analyze electromagnetic interactions on flat boundaries

2016 IEEE MTT-S International Microwave Symposium (IMS), 2016

A hands-on approach to avoid scientific debates and confusions about surface waves and Zenneck wa... more A hands-on approach to avoid scientific debates and confusions about surface waves and Zenneck waves are presented. The reflection coefficient for a TM incident wave on a flat boundary is studied as a function of the medium parameters in the most general way. When the second medium is lossy, the zero of this function results in a Zenneck wave and an infinite value represents a surface wave. Even though both Zenneck and surface waves are evanescent in nature and thus non-radiating, the field distribution for a Zenneck wave does not change with frequency whereas that of a surface wave gets concentrated near the surface with an increase in frequency. Finally a Zenneck wave can be excited by an electromagnetic wave but a surface wave requires electrons or quasiparticles in the form of an evanescent wave to be excited. Important questions are raised about some misused terminologies involving these two waves.

Electrically small antennas design challenges

2015 IEEE International Symposium on Antennas and Propagation & USNC/URSI National Radio Science Meeting, 2015

The Electrically Small Antennas (ESAs) perform well compared to larger antennas under matched con... more The Electrically Small Antennas (ESAs) perform well compared to larger antennas under matched conditions. In this paper, we study the difficulties in achieving a good design of an ESA matched to 50 O system. These difficulties are summarized in three topics: First, the Quality (Q) factor of an ESA, in general, is high and cannot be less than the Chu limit. The Q factor of an antenna is inversely proportional to the bandwidth of the antenna so this will impose a limit on the bandwidth of the antenna. Second, losses are always there in the impedance matching network, these losses associated with the matching network can dominate the small radiation resistance of an ESA which will degrade the efficiency of the ESA. Third, we are limited by the Fano-Bode gain-bandwidth limit when using the lossless passive matching network techniques. To overcome these issues, several solutions are presented briefly, either we try to alter the shape of the ESA so as to make the Q factor of the antenna close to the optimum lower limit or to use the concept of non-Foster matching networks to overcome the Fano-Bode limit. Finally, we design a four-arm meander line folded monopole which is considered an ESA at 1 GHz; it is shown that this design is matched to 50 Ω with low quality factor.

Measurements of-Band n-Type InSb Junction Circulators.................. ZM Ng, LE Davis, and R. Sloan 482 An RF Electronically Controlled Impedance Tuning Network Design and Its Application to an Antenna Input Impedance Automatic Matching System................. J. de Mingo, A. Valdovinos, A. Cre...

Parallel MoM simulation of complex EM problems

2009 IEEE Antennas and Propagation Society International Symposium, 2009

In this paper, a newly developed MoM code using higher-order basis functions and a parallel out-o... more In this paper, a newly developed MoM code using higher-order basis functions and a parallel out-of-core solver, TIDES, is run on a high performance parallel computing cluster. An aircraft carrier model and an airborne antenna array with radome are analyzed in this paper to demonstrate the TIDES code's capability. Numerical results indicate that TIDES provides an excellent solution for this

Electromagnetic macro model for analysis of propagation path loss in cellular networks

2014 IEEE Antennas and Propagation Society International Symposium (APSURSI), 2014

Received signal level measurements are frequently used to check the performance and the Quality o... more Received signal level measurements are frequently used to check the performance and the Quality of Service (QOS) inside the coverage area in cellular networks. These expensive time consuming measurements are carried out using an actual drive tests to assess the coverage area of a base station for a given cell and thus evaluate the QOS. In this paper, the novelty of the proposed electromagnetic analysis technique lies in its ability to match the macro model based simulation and measurement results without any statistical or empirical curve fitting or an adhoc choice of a reference distance. Furthermore, a new concept called proper route has been introduced to enhance the quality of measured data. The input parameters for the electromagnetic macro model can be generated using only the physical parameters of the environment like the height of the transmitting and receiving antennas over the ground, their tilts toward the ground, and the electrical parameters of the ground. A method of moments-based integral equation solver code called AWAS has been used to simulate the effects of the macro parameters of the environment. Measurements were carried out for cellular networks in western India and Sri Lanka.

A cursory historical overview on the evolution of wireless communications

2012 IEEE/MTT-S International Microwave Symposium Digest, 2012

ABSTRACT This presentation offers a historical overview on the evolution of field theory for wire... more ABSTRACT This presentation offers a historical overview on the evolution of field theory for wireless communications.

Finite-Element Time Domain Method

Time Domain Electromagnetics, 1999

A thin and compact high gain planar antenna integrated with a CMRC compact filter

2014 IEEE International Wireless Symposium (IWS 2014), 2014

ABSTRACT This paper presents a thin and compact high gain planar antenna integrated with a CMRC c... more ABSTRACT This paper presents a thin and compact high gain planar antenna integrated with a CMRC compact filter. The high gain antenna is a 4 element broadside microstrip array fed by parasitic coupling. The antenna is developed on a thin substrate of 0.762 mm thick. The broadside gain is 11.37 dBi at 5.5 GHz. The CMRC filter has filtered out the higher order modes of the micostrip antenna till 16 GHz. The sizes of the antenna array with and without the CMRC filter are exactly the same. Therefore, the design presented is a promising technique in designing a thin and compact high gain planar antenna with low-noise received.

Filter Model Generation from Scattering Parameters using the Cauchy Method

32nd European Microwave Conference, 2002, 2002

A method to obtain an accurate band-pass filter model from numerically computed or measured data ... more A method to obtain an accurate band-pass filter model from numerically computed or measured data is presented. A modified new version of the Cauchy technique that uses simultaneously both transmission (S21(f)) and reflection (S11(f)) parameters is applied in order to find a rational polynomial characterization of the filter. From this rational model the coupling structure can be extracted, revealing the

The Design of an Ultrawideband T-Pulse With a Linear Phase Fitting the FCC Mask

IEEE Transactions on Antennas and Propagation, 2011

ABSTRACT A discrete finite time domain pulse is designed under the constraint of the Federal Comm... more ABSTRACT A discrete finite time domain pulse is designed under the constraint of the Federal Communications Commission (FCC) ultrawideband (UWB) spectral mask. This pulse also enjoys the advantage of having a linear phase over the frequency band of interest and is orthogonal to its shifted version of one or more baud time. The finite time pulse is designed by an optimization method and concentrates its energy in the allowed bands specified by the FCC. Finally, an example is presented to illustrate how these types of wideband pulses can be transmitted and received with little distortion.

IEEE Transactions on Antennas and Propagation, 2011

The marching-on-in-degree (MOD) method has been presented earlier for solving time domain electri... more The marching-on-in-degree (MOD) method has been presented earlier for solving time domain electric field integral equations in a stable fashion. This is accomplished by expanding the transient responses by a complete set of orthogonal entire domain associated Laguerre functions, which helps one to analytically integrate out the time variable from the final computations in a Galerkin methodology. So, the final computations are carried out using only the spatial variables. However, the existing MOD method suffers from low computational efficiency over a marching-on-in-time (MOT) method. The two main causes of the computational inefficiency in the previous MOD method are now addressed using a new form of the temporal basis functions and through a different computational arrangement for the Green's function. In this paper, it is shown that incorporating these two new concepts can speed up the computational process and make it comparable to a MOT algorithm. Sample numerical results are presented to illustrate the validity of these claims in solution of large problems using the MOD method. Index Terms-Laguerre polynomials, marching-on-in-degree (MOD) method, marching-on-in-time (MOT) method, method of moments (MoM), time domain electric field integral equation (TD-EFIE).

Analytical Coupled-Resonator Filter Synthesis Method by Extraction of Fully Canonical Second Order Blocks

IEEE Microwave and Wireless Components Letters, 2013

ABSTRACT This work presents an analytical method for extraction of cascaded fully canonical secon... more ABSTRACT This work presents an analytical method for extraction of cascaded fully canonical second order blocks, formed by two resonators with a direct input-output coupling that generates two transmission zeros. Starting from the transfer matrix of the complete network and the specification of the transmission zeros, the method finds a decomposition of the transfer polynomials into two new sets corresponding to the second order subnetwork and the remaining one. To do so, the general solution of the extracted block transfer matrix is computed at each transmission zero. Then, both solutions are used to solve the complete polynomials. In order to illustrate the use of the algorithm, an analytical synthesis of a seventh order filter with four transmission zeros is included. The network topology corresponds to two cascaded quadruplets sharing one resonator.

Design and Testing of a Single-Layer Microstrip Ultrawideband 90° Differential Phase Shifter

IEEE Microwave and Wireless Components Letters, 2013

ABSTRACT This letter proposes a design of single-layer microstrip ultrawideband (UWB) 90° differe... more ABSTRACT This letter proposes a design of single-layer microstrip ultrawideband (UWB) 90° differential phase shifter. The operating bandwidth covers the UWB frequency range from 3.1-10.6 GHz. The design is optimized using a transmission line model and an electromagnetic model, and have been fabricated using a plotter dealing with generation of printed circuits. The measured S11 is better than -10 dB and S21 is better than -0.96 dB within the UWB frequency range. The simulated and measured phase deviation of the differential phase shift are 90°±5.23° and 90°±9.02°, respectively. The advantages of the proposed design are the simple fabrication, low insertion loss, and broad bandwidth.

An Exposition on the Choice of the Proper S Parameters in Characterizing Devices Including Transmission Lines with Complex Reference Impedances and a General Methodology for Computing Them

IEEE Antennas and Propagation Magazine, 2013

ABSTRACT The purpose of this paper is to demonstrate that the recently published paper [1] dealin... more ABSTRACT The purpose of this paper is to demonstrate that the recently published paper [1] dealing with little known facts and some new results on transmission lines is due to an incomplete interpretation of the nonphysical artifacts resulting from a particular mathematical model for the S parameters. These artifacts are not real and do not exist when a different form of the S parameters is used.The first objective of this paper is thus to introduce the two different types of S parameters generally used to characterize microwave circuits with lossy characteristic impedance. The first type is called the pseudo wave, an extension of the conventional traveling-wave concepts, and is useful when it is necessary to discuss the properties of a microwave network junction, irrespective of the impedances connected to the terminals. However, one has to be extremely careful in providing a physical interpretation of the mathematical expressions, as in this case the reflection coefficient can be greater than one, even for a passive load impedance with a conjugately matched transmission line. The power balance also cannot be simply obtained from the powers associated with the incident and reflected waves. Hence, this cannot be applied for broadband characterization of antennas. The second type of S parameter is called the power-wave scattering parameter. This is useful when one is interested in the power relationship between microwave circuits connected through a junction. In this case, the magnitude of the reflection coefficient cannot exceed unity, and the power delivered to the load is directly given by the difference between the powers associated with the incident and the reflected waves. Since this methodology deals with the reciprocal relationships between powers from various devices, this may be quite suitable for dealing with a pair of transmitting and receiving antennas where power reciprocity holds. This methodology is also applicable in network theory, where the scattering matr- x of a two-port (or a multi-port) can be defined using complex reference impedances at each of the ports without any transmission line being present, so that the concept of characteristic impedances becomes irrelevant. Such a situation is typical in small-signal microwave transistor amplifiers, where the analysis necessitates the use of complex reference impedances in order to study simultaneous matching and stability. However, for both definitions for the S parameters, when the characteristic impedance or the reference impedance is complex, the scattering matrix does not need to be symmetric, even if the network in question is reciprocal.The second objective is to illustrate that when the characteristic impedance of the line or the reference impedances in question is real and positive, then both of the pseudo-wave and the power-wave scattering parameters provide the same results. Finally, a general methodology is presented with examples to illustrate how the S parameters can be computed for an arbitrary network without any a priori knowledge of its characteristic impedance.

Full Wave Analysis of Geometrically Complex Anisotropic MMIC Waveguiding Structures

Theoretical and Experimental Study of Interference in Multibeam Active Phased Array Transmit Antenna for Satellite Communications...................................................... KJ Maalouf and E. Lier 587 Reduction of Truncation Error in Near-Field Measurements of Antennas of Base-Station M...

Use of the Output Energy Filter in Multiantenna Systems for Adaptive Estimation

Physics of Multiantenna Systems and Broadband Processing, 2007

2005 IEEE Antennas and Propagation Society International Symposium

In this paper polarization adaptivity on transmit has been used to enhance the received signals d... more In this paper polarization adaptivity on transmit has been used to enhance the received signals directed to a pre-selected receiver in a near-field multi-input multi-output (MIMO) environment. The objective here is to select a set of weights on the transmitting antennas adapted to individual receivers based on the principles of reciprocity. Using the polarization properties, when the number of receiving antennas is greater than the number of transmitting antennas, the transmitted signal may be directed more to a particular receiver location while simultaneously minimizing the reception signal strength at other receivers. Numerical simulations have been made to illustrate the novelty of the proposed approach.

Solving large complex problems using a higher-order basis: parallel in-core and out-of-core integral-equation solvers

IEEE Antennas and Propagation Magazine, 2008

Abstract The future of computational electromagnetics is changing drastically with the new genera... more Abstract The future of computational electromagnetics is changing drastically with the new generation of computer chips, which are multi-cored instead of single-cored. Previously, advancements in chip technology meant an increase in clock speed, which was typically a ...

Predicting the starting distance of the far field

2016 IEEE International Symposium on Antennas and Propagation (APSURSI), 2016

The far field of an antenna is generally considered to be the region where the outgoing wavefront... more The far field of an antenna is generally considered to be the region where the outgoing wavefront is planar and the antenna radiation pattern has a polar variation and is independent of the distance from the antenna. Hence, to generate a locally plane wave in the far field the radial component of the electric field must be negligible compared to the transverse component. Also, the ratio of the electric and the magnetic far fields should equal the intrinsic impedance of the medium. These two requirements must hold in all angular directions from the antenna. The radial and the transverse components of the fields are space dependent so to determine the starting distance of the far field we need to examine the simultaneous satisfaction of these two properties for all θ and φ angular directions, where θ is the angle measured from z-axis and φ is the angle measured from the x-axis. The objective of this paper can be summarized in three points: First, this paper intends to illustrate that 2D2/λ formula, where D is the maximum dimension of the antenna and λ is the operating wavelength, is not universally valid, it is only valid for antennas where D ≫ λ. Second, this paper intends to compute a more specific constraint so instead of D ≫ λ we compute a threshold for D after which the 2D2/λ formula applies. Third, this paper intends to properly interpret D in the formula 2D2/λ when the antenna is operating over an imperfect ground plane. In this paper, we do not use 2D2/λ for antennas operating over an imperfect ground instead we use a formula which depends on the transmitting and receiving antenna's heights over the air-Earth interface.

A hands-on approach for engineering students and practitioners to analyze electromagnetic interactions on flat boundaries

2016 IEEE MTT-S International Microwave Symposium (IMS), 2016

A hands-on approach to avoid scientific debates and confusions about surface waves and Zenneck wa... more A hands-on approach to avoid scientific debates and confusions about surface waves and Zenneck waves are presented. The reflection coefficient for a TM incident wave on a flat boundary is studied as a function of the medium parameters in the most general way. When the second medium is lossy, the zero of this function results in a Zenneck wave and an infinite value represents a surface wave. Even though both Zenneck and surface waves are evanescent in nature and thus non-radiating, the field distribution for a Zenneck wave does not change with frequency whereas that of a surface wave gets concentrated near the surface with an increase in frequency. Finally a Zenneck wave can be excited by an electromagnetic wave but a surface wave requires electrons or quasiparticles in the form of an evanescent wave to be excited. Important questions are raised about some misused terminologies involving these two waves.

Electrically small antennas design challenges

2015 IEEE International Symposium on Antennas and Propagation & USNC/URSI National Radio Science Meeting, 2015

The Electrically Small Antennas (ESAs) perform well compared to larger antennas under matched con... more The Electrically Small Antennas (ESAs) perform well compared to larger antennas under matched conditions. In this paper, we study the difficulties in achieving a good design of an ESA matched to 50 O system. These difficulties are summarized in three topics: First, the Quality (Q) factor of an ESA, in general, is high and cannot be less than the Chu limit. The Q factor of an antenna is inversely proportional to the bandwidth of the antenna so this will impose a limit on the bandwidth of the antenna. Second, losses are always there in the impedance matching network, these losses associated with the matching network can dominate the small radiation resistance of an ESA which will degrade the efficiency of the ESA. Third, we are limited by the Fano-Bode gain-bandwidth limit when using the lossless passive matching network techniques. To overcome these issues, several solutions are presented briefly, either we try to alter the shape of the ESA so as to make the Q factor of the antenna close to the optimum lower limit or to use the concept of non-Foster matching networks to overcome the Fano-Bode limit. Finally, we design a four-arm meander line folded monopole which is considered an ESA at 1 GHz; it is shown that this design is matched to 50 Ω with low quality factor.

Measurements of-Band n-Type InSb Junction Circulators.................. ZM Ng, LE Davis, and R. Sloan 482 An RF Electronically Controlled Impedance Tuning Network Design and Its Application to an Antenna Input Impedance Automatic Matching System................. J. de Mingo, A. Valdovinos, A. Cre...

Parallel MoM simulation of complex EM problems

2009 IEEE Antennas and Propagation Society International Symposium, 2009

In this paper, a newly developed MoM code using higher-order basis functions and a parallel out-o... more In this paper, a newly developed MoM code using higher-order basis functions and a parallel out-of-core solver, TIDES, is run on a high performance parallel computing cluster. An aircraft carrier model and an airborne antenna array with radome are analyzed in this paper to demonstrate the TIDES code's capability. Numerical results indicate that TIDES provides an excellent solution for this

Electromagnetic macro model for analysis of propagation path loss in cellular networks

2014 IEEE Antennas and Propagation Society International Symposium (APSURSI), 2014

Received signal level measurements are frequently used to check the performance and the Quality o... more Received signal level measurements are frequently used to check the performance and the Quality of Service (QOS) inside the coverage area in cellular networks. These expensive time consuming measurements are carried out using an actual drive tests to assess the coverage area of a base station for a given cell and thus evaluate the QOS. In this paper, the novelty of the proposed electromagnetic analysis technique lies in its ability to match the macro model based simulation and measurement results without any statistical or empirical curve fitting or an adhoc choice of a reference distance. Furthermore, a new concept called proper route has been introduced to enhance the quality of measured data. The input parameters for the electromagnetic macro model can be generated using only the physical parameters of the environment like the height of the transmitting and receiving antennas over the ground, their tilts toward the ground, and the electrical parameters of the ground. A method of moments-based integral equation solver code called AWAS has been used to simulate the effects of the macro parameters of the environment. Measurements were carried out for cellular networks in western India and Sri Lanka.

A cursory historical overview on the evolution of wireless communications

2012 IEEE/MTT-S International Microwave Symposium Digest, 2012

ABSTRACT This presentation offers a historical overview on the evolution of field theory for wire... more ABSTRACT This presentation offers a historical overview on the evolution of field theory for wireless communications.

Finite-Element Time Domain Method

Time Domain Electromagnetics, 1999

A thin and compact high gain planar antenna integrated with a CMRC compact filter

2014 IEEE International Wireless Symposium (IWS 2014), 2014

ABSTRACT This paper presents a thin and compact high gain planar antenna integrated with a CMRC c... more ABSTRACT This paper presents a thin and compact high gain planar antenna integrated with a CMRC compact filter. The high gain antenna is a 4 element broadside microstrip array fed by parasitic coupling. The antenna is developed on a thin substrate of 0.762 mm thick. The broadside gain is 11.37 dBi at 5.5 GHz. The CMRC filter has filtered out the higher order modes of the micostrip antenna till 16 GHz. The sizes of the antenna array with and without the CMRC filter are exactly the same. Therefore, the design presented is a promising technique in designing a thin and compact high gain planar antenna with low-noise received.

Filter Model Generation from Scattering Parameters using the Cauchy Method

32nd European Microwave Conference, 2002, 2002

A method to obtain an accurate band-pass filter model from numerically computed or measured data ... more A method to obtain an accurate band-pass filter model from numerically computed or measured data is presented. A modified new version of the Cauchy technique that uses simultaneously both transmission (S21(f)) and reflection (S11(f)) parameters is applied in order to find a rational polynomial characterization of the filter. From this rational model the coupling structure can be extracted, revealing the

The Design of an Ultrawideband T-Pulse With a Linear Phase Fitting the FCC Mask

IEEE Transactions on Antennas and Propagation, 2011

ABSTRACT A discrete finite time domain pulse is designed under the constraint of the Federal Comm... more ABSTRACT A discrete finite time domain pulse is designed under the constraint of the Federal Communications Commission (FCC) ultrawideband (UWB) spectral mask. This pulse also enjoys the advantage of having a linear phase over the frequency band of interest and is orthogonal to its shifted version of one or more baud time. The finite time pulse is designed by an optimization method and concentrates its energy in the allowed bands specified by the FCC. Finally, an example is presented to illustrate how these types of wideband pulses can be transmitted and received with little distortion.

IEEE Transactions on Antennas and Propagation, 2011

The marching-on-in-degree (MOD) method has been presented earlier for solving time domain electri... more The marching-on-in-degree (MOD) method has been presented earlier for solving time domain electric field integral equations in a stable fashion. This is accomplished by expanding the transient responses by a complete set of orthogonal entire domain associated Laguerre functions, which helps one to analytically integrate out the time variable from the final computations in a Galerkin methodology. So, the final computations are carried out using only the spatial variables. However, the existing MOD method suffers from low computational efficiency over a marching-on-in-time (MOT) method. The two main causes of the computational inefficiency in the previous MOD method are now addressed using a new form of the temporal basis functions and through a different computational arrangement for the Green's function. In this paper, it is shown that incorporating these two new concepts can speed up the computational process and make it comparable to a MOT algorithm. Sample numerical results are presented to illustrate the validity of these claims in solution of large problems using the MOD method. Index Terms-Laguerre polynomials, marching-on-in-degree (MOD) method, marching-on-in-time (MOT) method, method of moments (MoM), time domain electric field integral equation (TD-EFIE).

Analytical Coupled-Resonator Filter Synthesis Method by Extraction of Fully Canonical Second Order Blocks

IEEE Microwave and Wireless Components Letters, 2013

ABSTRACT This work presents an analytical method for extraction of cascaded fully canonical secon... more ABSTRACT This work presents an analytical method for extraction of cascaded fully canonical second order blocks, formed by two resonators with a direct input-output coupling that generates two transmission zeros. Starting from the transfer matrix of the complete network and the specification of the transmission zeros, the method finds a decomposition of the transfer polynomials into two new sets corresponding to the second order subnetwork and the remaining one. To do so, the general solution of the extracted block transfer matrix is computed at each transmission zero. Then, both solutions are used to solve the complete polynomials. In order to illustrate the use of the algorithm, an analytical synthesis of a seventh order filter with four transmission zeros is included. The network topology corresponds to two cascaded quadruplets sharing one resonator.

Design and Testing of a Single-Layer Microstrip Ultrawideband 90° Differential Phase Shifter

IEEE Microwave and Wireless Components Letters, 2013

ABSTRACT This letter proposes a design of single-layer microstrip ultrawideband (UWB) 90° differe... more ABSTRACT This letter proposes a design of single-layer microstrip ultrawideband (UWB) 90° differential phase shifter. The operating bandwidth covers the UWB frequency range from 3.1-10.6 GHz. The design is optimized using a transmission line model and an electromagnetic model, and have been fabricated using a plotter dealing with generation of printed circuits. The measured S11 is better than -10 dB and S21 is better than -0.96 dB within the UWB frequency range. The simulated and measured phase deviation of the differential phase shift are 90°±5.23° and 90°±9.02°, respectively. The advantages of the proposed design are the simple fabrication, low insertion loss, and broad bandwidth.

An Exposition on the Choice of the Proper S Parameters in Characterizing Devices Including Transmission Lines with Complex Reference Impedances and a General Methodology for Computing Them

IEEE Antennas and Propagation Magazine, 2013

ABSTRACT The purpose of this paper is to demonstrate that the recently published paper [1] dealin... more ABSTRACT The purpose of this paper is to demonstrate that the recently published paper [1] dealing with little known facts and some new results on transmission lines is due to an incomplete interpretation of the nonphysical artifacts resulting from a particular mathematical model for the S parameters. These artifacts are not real and do not exist when a different form of the S parameters is used.The first objective of this paper is thus to introduce the two different types of S parameters generally used to characterize microwave circuits with lossy characteristic impedance. The first type is called the pseudo wave, an extension of the conventional traveling-wave concepts, and is useful when it is necessary to discuss the properties of a microwave network junction, irrespective of the impedances connected to the terminals. However, one has to be extremely careful in providing a physical interpretation of the mathematical expressions, as in this case the reflection coefficient can be greater than one, even for a passive load impedance with a conjugately matched transmission line. The power balance also cannot be simply obtained from the powers associated with the incident and reflected waves. Hence, this cannot be applied for broadband characterization of antennas. The second type of S parameter is called the power-wave scattering parameter. This is useful when one is interested in the power relationship between microwave circuits connected through a junction. In this case, the magnitude of the reflection coefficient cannot exceed unity, and the power delivered to the load is directly given by the difference between the powers associated with the incident and the reflected waves. Since this methodology deals with the reciprocal relationships between powers from various devices, this may be quite suitable for dealing with a pair of transmitting and receiving antennas where power reciprocity holds. This methodology is also applicable in network theory, where the scattering matr- x of a two-port (or a multi-port) can be defined using complex reference impedances at each of the ports without any transmission line being present, so that the concept of characteristic impedances becomes irrelevant. Such a situation is typical in small-signal microwave transistor amplifiers, where the analysis necessitates the use of complex reference impedances in order to study simultaneous matching and stability. However, for both definitions for the S parameters, when the characteristic impedance or the reference impedance is complex, the scattering matrix does not need to be symmetric, even if the network in question is reciprocal.The second objective is to illustrate that when the characteristic impedance of the line or the reference impedances in question is real and positive, then both of the pseudo-wave and the power-wave scattering parameters provide the same results. Finally, a general methodology is presented with examples to illustrate how the S parameters can be computed for an arbitrary network without any a priori knowledge of its characteristic impedance.

Full Wave Analysis of Geometrically Complex Anisotropic MMIC Waveguiding Structures

Theoretical and Experimental Study of Interference in Multibeam Active Phased Array Transmit Antenna for Satellite Communications...................................................... KJ Maalouf and E. Lier 587 Reduction of Truncation Error in Near-Field Measurements of Antennas of Base-Station M...