Leonel Soriano-Equigua - Academia.edu (original) (raw)

Papers by Leonel Soriano-Equigua

Journal of Applied Research and Technology, 2011

Coordinated beamforming based on singular value decomposition is an iterative method to jointly o... more Coordinated beamforming based on singular value decomposition is an iterative method to jointly optimize the transmit beamformers and receive combiners, to achieve high levels of sum rates in the downlink of multiuser systems, by exploiting the multi-dimensional wireless channel created by multiple transmit and receive antennas. The optimization is done at the base station and the quantized beamformers are sent to the users through a low rate link.In this work, we propose to optimize this algorithm by reducing the number of iterations and improving its uncoded bit error rate performance. Simulation results show that our proposal achieves a better bit error rate with a lower number of iterations than the original algorithm.

Electronics, 2022

Current small satellite platforms such as CubeSats require robust and versatile communication sub... more Current small satellite platforms such as CubeSats require robust and versatile communication subsystems that allow the reconfiguration of the critical operating parameters such as carrier frequency, transmission power, bandwidth, or filter roll-off factor. A reconfigurable Analog Back-End for the space segment of a satellite communication subsystem is presented in this work. This prototype is implemented on a 9.5 cm2 6-layer PCB, and it operates from 0.070 to 6 GHz and complies with CubeSat and IPC-2221 standards. The processing, control, and synchronizing stages are carried out on a Software-Defined Radio approach executed on a baseband processor. Results showed that the signal power at the output of the proposed Analog Back-End is suitable for feeding the following antenna subsystem. Furthermore, the emitted radiation levels by the transmission lines do not generate electromagnetic interference.

2018 11th International Symposium on Communication Systems, Networks & Digital Signal Processing (CSNDSP), 2018

Wireless communications have evolved rapidly over the years and today they are present everywhere... more Wireless communications have evolved rapidly over the years and today they are present everywhere. A fundamental aspect of wireless communications is that they all share the same medium, so interference has always been an issue to be considered. Taking advantage of the multiuser diversity offered by ultra-dense networks (UDNs), the Opportunistic Interference Alignment (OIA) techniques have become a very attractive solution for the Multiple-Input Multiple-Output Interfering Broadcast Channels (MIMO-IBC). In conventional OIA techniques, each user measures the level of correlation of the interfering signals received by the adjacent cells, sends this information to the corresponding base station (BS) station through a feedback link, and then, the BS makes a decision of which user will attend at a given time in a decentralized way. In this article, an OIA technique based on the volume of the parallelepiped formed by the interfering signals is proposed. The simulation results show that the proposed technique achieves a substantial improvement over conventional techniques especially at high signal-to-noise ratio (SNR) under correlated channels; in addition, a complexity analysis is presented to demonstrate the feasibility of the proposed technique.

Current small satellite platforms such as CubeSats, require robust and versatile communication su... more Current small satellite platforms such as CubeSats, require robust and versatile communication subsystems that allow the reconfiguration of the critical operation parameters such as carrier frequency, transmission power, bandwidth, or filter roll-off factor. In this paper, a reconfigurable Analog Back-End for CubeSat communications is proposed. This prototype is implemented using CAD software, on a 6-layer PCB of 10 cm^2 to implement a transceiver that operates from 0.070 to 6 GHz and complying with CubeSat and IPC-2221 standards. An Software-Defined Radio approach implemented on a baseband processor is used for control purposes. Measurements showed that the signal power at the output of the proposed analog back-end is suitable to feed the subsequent antenna subsystem.

In recent years, reaching agreements is an important problem in multi-agent systems (MAS), which ... more In recent years, reaching agreements is an important problem in multi-agent systems (MAS), which require different types of dialogues between agents. Persuasion is one of them and it is traditionally based on first order logic. However, this type of technique is not adequate for solving complex problems. This situation requires developing new models for optimizing an agent persuasion process. This work presents a persuasion model for MAS based in genetic algorithms (GA) for reaching agreements in problem solving. The objective of this work is to optimize the negotiation between agents that solve complex problems. First, it was designed the persuasion model. Then, it was implemented and evaluated in experimental scenarios and it was compared its results against traditional models. The experimental results showed that a GA-oriented persuasion model optimizes the negotiation in MAS by improving execution time, which also eventually will optimize the processes carried out by MAS.

IEEE Latin America Transactions, 2021

Research on student performance prediction has evolved from the early application of statistical ... more Research on student performance prediction has evolved from the early application of statistical techniques to later use of computational techniques. Results in this field are varied, thus, we have to take advantage of previous research results. This study proposes a Multi-layer Adaptive Neuro-Fuzzy Inference System (MANFIS) for student performance prediction in online Higher Education settings. The MANFIS was trained and tested using a dataset integrated by the scores obtained by students in four online Higher Education courses. The MANFIS prediction accuracy was compared against the accuracies of Multilayer neural network, Radial Basis Function Neural Network, and General Regression Neural Network. The accuracy of the MANFIS prediction statistically outperformed at least one neural network (out of three possible) in each dataset. The Results indicate that MANFIS is an alternative model to predict student performance in online Higher Education settings.

2016 2nd International Conference on Frontiers of Signal Processing (ICFSP), 2016

Full-duplex (FD) is a very promising technique that offers the potential to double the spectral e... more Full-duplex (FD) is a very promising technique that offers the potential to double the spectral efficiency. In this paper, the achievable rate for uplink-downlink user and antenna selection in poor scattering channels of FD multiuser system is studied. The considered FD communication system consists of one FD multi-antenna base station (BS) and multiple half duplex (HD) single antenna mobile terminals (MTs). Simulation results show the achievable sum-rate for practical number of users in the system.

2015 International Conference on Information and Communication Technology Convergence (ICTC), 2015

This paper presents two practical user scheduling strategies for the M-cell Multiple-Input Multip... more This paper presents two practical user scheduling strategies for the M-cell Multiple-Input Multiple-Output Interference Channels (MIMO-IC). In the proposed schemes the transmitter selects the user with greater difference between the volume of the desired signal subspace and the volume of the interference subspace assuming only local channel knowledge at the Base Station. Simulation results show the effectiveness of the proposed algorithms achieving an improvement in with a moderate number of users in each cell compared to low complexity algorithms proposed in the literature.

Revista Iberoamericana de Automatica e Informatica Industrial (RIAI)

el cordón umbilical del que anteriormente se dependía para lograr establecer una conexión con el ... more el cordón umbilical del que anteriormente se dependía para lograr establecer una conexión con el fin de compartir información y/o datos. Para lograr la conexión es necesario establecer en primer lugar el tipo de protocolo a utilizar, para lo cual el mercado ha comenzado a llenar con las diferentes posibilidades para establecer la comunicación y ha dado lugar a diversos estándares. Entre ellos esta los reconocidos por la IEEE que son de la familia 802.11x. En este trabajo se utilizaron dos estándares; 802.11b y 802.11g, para conocer las ventajas de ellos, determinar la distancia, establecer procedimientos para lograr mediciones y determinar cual estándar pudiese funcionar mejor con la infraestructura física en el área a cubrir por la radiación de la señal inalámbrica. Palabras Claves: WI FI, WLAN, 802.11b, 802.11g, Desempeño. 1. INTRODUCCIÓN. Es deprimente el observar como hay personas que olvidan la historia y en algún momento de sus actividades personales/profesionales son condenad...

En la Universidad de Colima hay un servicio de red inalámbrica gratuito para los estudiantes, así... more En la Universidad de Colima hay un servicio de red inalámbrica gratuito para los estudiantes, así como para los trabajadores de esta institución. Con el objetivo de ofrecer un servicio de conectividad de alta calidad se propuso analizar la señal que cubre el área de la Universidad en la frecuencia libre de 2.4 GHz. En esta investigación se presenta un análisis exhaustivo de la cobertura de su patrón de radiación, así como los mapas de pérdida de señal y velocidad de transmisión trabajando en el campus principal de la Universidad de Colima

ABSTRACT Reaching agreements is an important problem in multi-agent systems (MAS), which requires... more ABSTRACT Reaching agreements is an important problem in multi-agent systems (MAS), which requires different types of dialogues between agents. Persuasion is one of them and it is predominantly based in first order logic. However, this type of dialogue is not an adequate approach for solving complex problems - those that can't be solved in polynomial time. This paper presents a persuasion model for MAS which consider the fitness function of a genetic algorithm (GA) for reaching agreements in problem solving. The resulting persuasion model provides each member of MAS with a fitness function capable of guiding agents in the reach of agreements. The evaluation we did enabled us to state that the model could have a positive impact for solving complex problems with MAS. In contrast with previous studies, our results highlight the importance of using a GA persuasion model for solving complex problems and we depict the implications of our findings in its design considerations.

IEICE Transactions on Communications, 2011

ABSTRACT Overhead Reduction in Coordinated Beamforming for Multiuser MIMO-OFDM Systems with Limit... more ABSTRACT Overhead Reduction in Coordinated Beamforming for Multiuser MIMO-OFDM Systems with Limited Feedforward

IEEE Signal Processing Letters, 2009

A method for reducing feedback in a downlink Multiuser MIMO-OFDM cellular system, with zero forci... more A method for reducing feedback in a downlink Multiuser MIMO-OFDM cellular system, with zero forcing beamforming at the base (BS) and antenna combining at each mobile (MS) is proposed. The method consists of partitioning the subcarriers into groups, choosing the quantized channel vector that better represents each group in terms of average quantization error. Numerical results show that savings up to 93% in overhead bits are obtained for SNR equal to 15 dB, with reductions in channel capacity that goes from 30% to 50% depending on the codebook size used for quantization.

IEEE Latin America Transactions, 2015

In this paper a study of the existing scheduling algorithms for Multiuser-MIMO wireless systems i... more In this paper a study of the existing scheduling algorithms for Multiuser-MIMO wireless systems is provided. The behavior of the these algorithms is analyzed for a large-scale antenna systems known as Massive MIMO, where it is proposed to use a lot of antennas to multiplex messages to several user devices at each time and frequency resource. Simulation results show that Massive MIMO systems, in conjunction with scheduling algorithms, offer a great channel capacity even with channel imperfections and can be seen as disruptive techniques to future 5G wireless communication systems.

IEEE Signal Processing Letters, 2011

How to cite Complete issue More information about this article Journal's homepage in redalyc.org ... more How to cite Complete issue More information about this article Journal's homepage in redalyc.org Scientific Information System Network of Scientific Journals from Latin America, the Caribbean, Spain and Portugal Non-profit academic project, developed under the open access initiative Vol.9 No.

IEEE Latin America Transactions, 2021

Research on student performance prediction has evolved from the early application of statistical ... more Research on student performance prediction has evolved from the early application of statistical techniques to later use of computational techniques. Results in this field are varied, thus, we have to take advantage of previous research results. This study proposes a Multi-layer Adaptive Neuro-Fuzzy Inference System (MANFIS) for student performance prediction in online Higher Education settings. The MANFIS was trained and tested using a dataset integrated by the scores obtained by students in four online Higher Education courses. The MANFIS prediction accuracy was compared against the accuracies of Multilayer neural network, Radial Basis Function Neural Network, and General Regression Neural Network. The accuracy of the MANFIS prediction statistically outperformed at least one neural network (out of three possible) in each dataset. The Results indicate that MANFIS is an alternative model to predict student performance in online Higher Education settings.

International Journal of Antennas and Propagation

This article presents the design, fabrication, and measurement of a square Koch fractal slot ante... more This article presents the design, fabrication, and measurement of a square Koch fractal slot antenna for UHF band using both the FR4-G10 and Cuclad 250 substrates. Conveniently, this 56.56 cm full-length antenna possesses a geometry that allows it to be incorporated into the standardized 10 cm × 10 cm faces of the CubeSats. Furthermore, it is shown that both selected substrates exhibit an acceptable performance at the frequency of interest despite the economic cost difference and relative permittivity. Hence, the commercial FR4-G10 antenna substrate can be preferred because of its low-cost and admissible performance at 458 MHz, which is a frequency in the UHF band that is commonly used for telemetry, tracking, and command downlinks of CubeSats. Measurements show that the proposed antenna exhibits a reflection coefficient of −16.53 dB, a bandwidth of 22.62 MHz at −10 dB, a VSWR of 1.3508, a normalized impedance of 0.794 − j0.173 at 50 Ω, and a directivity of 2.24 dBi. The contributio...

International Journal of Antennas and Propagation

In this work, a comparison of the microwave absorption properties of Opuntia ficus-indica cladode... more In this work, a comparison of the microwave absorption properties of Opuntia ficus-indica cladodes, Agave atrovirens branches, and Cocos nucifera L. husk samples was performed. The study was carried out by inserting dry and powdered samples of these organic materials transversely and in the middle of a rectangular waveguide, for which scattering parameters S21 and S11 were measured to estimate the absorption coefficient. These measurements were compared to determine the material that behaves the best as a microwave absorber with a view to develop future low-cost and eco-friendly products by reusing agricultural waste. Specifically, Agave atrovirens sample showed the best performance, having an average value of absorption coefficient of 0.4218, while its maximum was 0.5792 at 9.706 GHz within the range from 8.005 to 13 GHz.

Journal of Applied Research and Technology, 2011

Coordinated beamforming based on singular value decomposition is an iterative method to jointly o... more Coordinated beamforming based on singular value decomposition is an iterative method to jointly optimize the transmit beamformers and receive combiners, to achieve high levels of sum rates in the downlink of multiuser systems, by exploiting the multi-dimensional wireless channel created by multiple transmit and receive antennas. The optimization is done at the base station and the quantized beamformers are sent to the users through a low rate link.In this work, we propose to optimize this algorithm by reducing the number of iterations and improving its uncoded bit error rate performance. Simulation results show that our proposal achieves a better bit error rate with a lower number of iterations than the original algorithm.

Electronics, 2022

Current small satellite platforms such as CubeSats require robust and versatile communication sub... more Current small satellite platforms such as CubeSats require robust and versatile communication subsystems that allow the reconfiguration of the critical operating parameters such as carrier frequency, transmission power, bandwidth, or filter roll-off factor. A reconfigurable Analog Back-End for the space segment of a satellite communication subsystem is presented in this work. This prototype is implemented on a 9.5 cm2 6-layer PCB, and it operates from 0.070 to 6 GHz and complies with CubeSat and IPC-2221 standards. The processing, control, and synchronizing stages are carried out on a Software-Defined Radio approach executed on a baseband processor. Results showed that the signal power at the output of the proposed Analog Back-End is suitable for feeding the following antenna subsystem. Furthermore, the emitted radiation levels by the transmission lines do not generate electromagnetic interference.

2018 11th International Symposium on Communication Systems, Networks & Digital Signal Processing (CSNDSP), 2018

Wireless communications have evolved rapidly over the years and today they are present everywhere... more Wireless communications have evolved rapidly over the years and today they are present everywhere. A fundamental aspect of wireless communications is that they all share the same medium, so interference has always been an issue to be considered. Taking advantage of the multiuser diversity offered by ultra-dense networks (UDNs), the Opportunistic Interference Alignment (OIA) techniques have become a very attractive solution for the Multiple-Input Multiple-Output Interfering Broadcast Channels (MIMO-IBC). In conventional OIA techniques, each user measures the level of correlation of the interfering signals received by the adjacent cells, sends this information to the corresponding base station (BS) station through a feedback link, and then, the BS makes a decision of which user will attend at a given time in a decentralized way. In this article, an OIA technique based on the volume of the parallelepiped formed by the interfering signals is proposed. The simulation results show that the proposed technique achieves a substantial improvement over conventional techniques especially at high signal-to-noise ratio (SNR) under correlated channels; in addition, a complexity analysis is presented to demonstrate the feasibility of the proposed technique.

Current small satellite platforms such as CubeSats, require robust and versatile communication su... more Current small satellite platforms such as CubeSats, require robust and versatile communication subsystems that allow the reconfiguration of the critical operation parameters such as carrier frequency, transmission power, bandwidth, or filter roll-off factor. In this paper, a reconfigurable Analog Back-End for CubeSat communications is proposed. This prototype is implemented using CAD software, on a 6-layer PCB of 10 cm^2 to implement a transceiver that operates from 0.070 to 6 GHz and complying with CubeSat and IPC-2221 standards. An Software-Defined Radio approach implemented on a baseband processor is used for control purposes. Measurements showed that the signal power at the output of the proposed analog back-end is suitable to feed the subsequent antenna subsystem.

In recent years, reaching agreements is an important problem in multi-agent systems (MAS), which ... more In recent years, reaching agreements is an important problem in multi-agent systems (MAS), which require different types of dialogues between agents. Persuasion is one of them and it is traditionally based on first order logic. However, this type of technique is not adequate for solving complex problems. This situation requires developing new models for optimizing an agent persuasion process. This work presents a persuasion model for MAS based in genetic algorithms (GA) for reaching agreements in problem solving. The objective of this work is to optimize the negotiation between agents that solve complex problems. First, it was designed the persuasion model. Then, it was implemented and evaluated in experimental scenarios and it was compared its results against traditional models. The experimental results showed that a GA-oriented persuasion model optimizes the negotiation in MAS by improving execution time, which also eventually will optimize the processes carried out by MAS.

IEEE Latin America Transactions, 2021

Research on student performance prediction has evolved from the early application of statistical ... more Research on student performance prediction has evolved from the early application of statistical techniques to later use of computational techniques. Results in this field are varied, thus, we have to take advantage of previous research results. This study proposes a Multi-layer Adaptive Neuro-Fuzzy Inference System (MANFIS) for student performance prediction in online Higher Education settings. The MANFIS was trained and tested using a dataset integrated by the scores obtained by students in four online Higher Education courses. The MANFIS prediction accuracy was compared against the accuracies of Multilayer neural network, Radial Basis Function Neural Network, and General Regression Neural Network. The accuracy of the MANFIS prediction statistically outperformed at least one neural network (out of three possible) in each dataset. The Results indicate that MANFIS is an alternative model to predict student performance in online Higher Education settings.

2016 2nd International Conference on Frontiers of Signal Processing (ICFSP), 2016

Full-duplex (FD) is a very promising technique that offers the potential to double the spectral e... more Full-duplex (FD) is a very promising technique that offers the potential to double the spectral efficiency. In this paper, the achievable rate for uplink-downlink user and antenna selection in poor scattering channels of FD multiuser system is studied. The considered FD communication system consists of one FD multi-antenna base station (BS) and multiple half duplex (HD) single antenna mobile terminals (MTs). Simulation results show the achievable sum-rate for practical number of users in the system.

2015 International Conference on Information and Communication Technology Convergence (ICTC), 2015

This paper presents two practical user scheduling strategies for the M-cell Multiple-Input Multip... more This paper presents two practical user scheduling strategies for the M-cell Multiple-Input Multiple-Output Interference Channels (MIMO-IC). In the proposed schemes the transmitter selects the user with greater difference between the volume of the desired signal subspace and the volume of the interference subspace assuming only local channel knowledge at the Base Station. Simulation results show the effectiveness of the proposed algorithms achieving an improvement in with a moderate number of users in each cell compared to low complexity algorithms proposed in the literature.

Revista Iberoamericana de Automatica e Informatica Industrial (RIAI)

el cordón umbilical del que anteriormente se dependía para lograr establecer una conexión con el ... more el cordón umbilical del que anteriormente se dependía para lograr establecer una conexión con el fin de compartir información y/o datos. Para lograr la conexión es necesario establecer en primer lugar el tipo de protocolo a utilizar, para lo cual el mercado ha comenzado a llenar con las diferentes posibilidades para establecer la comunicación y ha dado lugar a diversos estándares. Entre ellos esta los reconocidos por la IEEE que son de la familia 802.11x. En este trabajo se utilizaron dos estándares; 802.11b y 802.11g, para conocer las ventajas de ellos, determinar la distancia, establecer procedimientos para lograr mediciones y determinar cual estándar pudiese funcionar mejor con la infraestructura física en el área a cubrir por la radiación de la señal inalámbrica. Palabras Claves: WI FI, WLAN, 802.11b, 802.11g, Desempeño. 1. INTRODUCCIÓN. Es deprimente el observar como hay personas que olvidan la historia y en algún momento de sus actividades personales/profesionales son condenad...

En la Universidad de Colima hay un servicio de red inalámbrica gratuito para los estudiantes, así... more En la Universidad de Colima hay un servicio de red inalámbrica gratuito para los estudiantes, así como para los trabajadores de esta institución. Con el objetivo de ofrecer un servicio de conectividad de alta calidad se propuso analizar la señal que cubre el área de la Universidad en la frecuencia libre de 2.4 GHz. En esta investigación se presenta un análisis exhaustivo de la cobertura de su patrón de radiación, así como los mapas de pérdida de señal y velocidad de transmisión trabajando en el campus principal de la Universidad de Colima

ABSTRACT Reaching agreements is an important problem in multi-agent systems (MAS), which requires... more ABSTRACT Reaching agreements is an important problem in multi-agent systems (MAS), which requires different types of dialogues between agents. Persuasion is one of them and it is predominantly based in first order logic. However, this type of dialogue is not an adequate approach for solving complex problems - those that can't be solved in polynomial time. This paper presents a persuasion model for MAS which consider the fitness function of a genetic algorithm (GA) for reaching agreements in problem solving. The resulting persuasion model provides each member of MAS with a fitness function capable of guiding agents in the reach of agreements. The evaluation we did enabled us to state that the model could have a positive impact for solving complex problems with MAS. In contrast with previous studies, our results highlight the importance of using a GA persuasion model for solving complex problems and we depict the implications of our findings in its design considerations.

IEICE Transactions on Communications, 2011

ABSTRACT Overhead Reduction in Coordinated Beamforming for Multiuser MIMO-OFDM Systems with Limit... more ABSTRACT Overhead Reduction in Coordinated Beamforming for Multiuser MIMO-OFDM Systems with Limited Feedforward

IEEE Signal Processing Letters, 2009

A method for reducing feedback in a downlink Multiuser MIMO-OFDM cellular system, with zero forci... more A method for reducing feedback in a downlink Multiuser MIMO-OFDM cellular system, with zero forcing beamforming at the base (BS) and antenna combining at each mobile (MS) is proposed. The method consists of partitioning the subcarriers into groups, choosing the quantized channel vector that better represents each group in terms of average quantization error. Numerical results show that savings up to 93% in overhead bits are obtained for SNR equal to 15 dB, with reductions in channel capacity that goes from 30% to 50% depending on the codebook size used for quantization.

IEEE Latin America Transactions, 2015

In this paper a study of the existing scheduling algorithms for Multiuser-MIMO wireless systems i... more In this paper a study of the existing scheduling algorithms for Multiuser-MIMO wireless systems is provided. The behavior of the these algorithms is analyzed for a large-scale antenna systems known as Massive MIMO, where it is proposed to use a lot of antennas to multiplex messages to several user devices at each time and frequency resource. Simulation results show that Massive MIMO systems, in conjunction with scheduling algorithms, offer a great channel capacity even with channel imperfections and can be seen as disruptive techniques to future 5G wireless communication systems.

IEEE Signal Processing Letters, 2011

How to cite Complete issue More information about this article Journal's homepage in redalyc.org ... more How to cite Complete issue More information about this article Journal's homepage in redalyc.org Scientific Information System Network of Scientific Journals from Latin America, the Caribbean, Spain and Portugal Non-profit academic project, developed under the open access initiative Vol.9 No.

IEEE Latin America Transactions, 2021

Research on student performance prediction has evolved from the early application of statistical ... more Research on student performance prediction has evolved from the early application of statistical techniques to later use of computational techniques. Results in this field are varied, thus, we have to take advantage of previous research results. This study proposes a Multi-layer Adaptive Neuro-Fuzzy Inference System (MANFIS) for student performance prediction in online Higher Education settings. The MANFIS was trained and tested using a dataset integrated by the scores obtained by students in four online Higher Education courses. The MANFIS prediction accuracy was compared against the accuracies of Multilayer neural network, Radial Basis Function Neural Network, and General Regression Neural Network. The accuracy of the MANFIS prediction statistically outperformed at least one neural network (out of three possible) in each dataset. The Results indicate that MANFIS is an alternative model to predict student performance in online Higher Education settings.

International Journal of Antennas and Propagation

This article presents the design, fabrication, and measurement of a square Koch fractal slot ante... more This article presents the design, fabrication, and measurement of a square Koch fractal slot antenna for UHF band using both the FR4-G10 and Cuclad 250 substrates. Conveniently, this 56.56 cm full-length antenna possesses a geometry that allows it to be incorporated into the standardized 10 cm × 10 cm faces of the CubeSats. Furthermore, it is shown that both selected substrates exhibit an acceptable performance at the frequency of interest despite the economic cost difference and relative permittivity. Hence, the commercial FR4-G10 antenna substrate can be preferred because of its low-cost and admissible performance at 458 MHz, which is a frequency in the UHF band that is commonly used for telemetry, tracking, and command downlinks of CubeSats. Measurements show that the proposed antenna exhibits a reflection coefficient of −16.53 dB, a bandwidth of 22.62 MHz at −10 dB, a VSWR of 1.3508, a normalized impedance of 0.794 − j0.173 at 50 Ω, and a directivity of 2.24 dBi. The contributio...

International Journal of Antennas and Propagation

In this work, a comparison of the microwave absorption properties of Opuntia ficus-indica cladode... more In this work, a comparison of the microwave absorption properties of Opuntia ficus-indica cladodes, Agave atrovirens branches, and Cocos nucifera L. husk samples was performed. The study was carried out by inserting dry and powdered samples of these organic materials transversely and in the middle of a rectangular waveguide, for which scattering parameters S21 and S11 were measured to estimate the absorption coefficient. These measurements were compared to determine the material that behaves the best as a microwave absorber with a view to develop future low-cost and eco-friendly products by reusing agricultural waste. Specifically, Agave atrovirens sample showed the best performance, having an average value of absorption coefficient of 0.4218, while its maximum was 0.5792 at 9.706 GHz within the range from 8.005 to 13 GHz.