The 8th European Conference on Antennas and Propagation (EuCAP 2014), 2014
In this work, a new ultra wide band circular ring patch antenna is proposed for spectral sensing ... more In this work, a new ultra wide band circular ring patch antenna is proposed for spectral sensing application as well as the transmission and reception of radiofrequency in cognitive radio systems. The proposed structure has simple design and easy construction, making it reconfigurable by enabling or disabling the parasitic elements coplanar to the antenna. Simulation and measurements results confirm good agreement and adequate antenna response in the frequency range from 3.1 GHz to 10.6 GHz, in terms of the reflection coefficient and radiation pattern, validating the applicability of the proposed structure for cognitive radio systems front-end.
O anel hibrido Rat-Race e um dispositivo acoplador de potencia de quatro portas com muitas aplica... more O anel hibrido Rat-Race e um dispositivo acoplador de potencia de quatro portas com muitas aplicacoes em circuitos de comunicacao para a faixa de micro-ondas e de ondas milimetricas. O anel hibrido descrito neste artigo e constituido de quatro secoes de microfita, uma de comprimento ¾λ e tres de comprimento ¼λ. O acoplamento entre as porta 1 e 2 (S12) e as portas 1 e 3 (S13) foram caracterizados com auxilio da ferramenta de analise Ansoft Designer TM , que implementa o metodo dos momentos (MoM). Em particular, foram verificadas as defasagens de sinais na faixa de micro-ondas transmitidos as portas de saida (2 e 3) apos a excitacao do circuito de microfita na porta de entrada 1. Com a finalidade de validar os resultados teoricos simulados, um prototipo do dispositivo foi fabricado e medido no laboratorio do INCTCSF-UFRN (Instituto Nacional de Ciencia e Tecnologia de Comunicacao Sem Fio).
2011 IEEE-APS Topical Conference on Antennas and Propagation in Wireless Communications, 2011
This work presents a study of implementation procedures for multi-slot microstrip patch antennas ... more This work presents a study of implementation procedures for multi-slot microstrip patch antennas characterization for wireless communication systems. An artificial neural network multilayer perceptron is used to locate the bands of operational frequencies of the antenna for different geometrics configurations. The antenna is designed, simulated and measured in laboratory. The obtained results are compared and a good agreement is observed.
SBMO/IEEE MTT-S International Conference on Microwave and Optoelectronics, 2005.
Abstract This work presents an efficient implementation of the 2.5D ray-tracing method for mode... more Abstract This work presents an efficient implementation of the 2.5D ray-tracing method for modeling indoor propagation. The implementation is made by means of graphic software tools using the shooting and bouncing rays (SBR) technique, in combination with the uniform ...
International Journal of Infrared and Millimeter Waves, 2000
A full wave analysis is developed for frequency selective surfaces composed of rectangular patche... more A full wave analysis is developed for frequency selective surfaces composed of rectangular patches mounted on a dielectric anisotropic substrate and covered with a uniaxial anisotropic superstrate. The moment method is used in combination with the spectral domain immittance approach to determine the FSS structure reflection and transmission coefficients.
2011 SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference (IMOC 2011), 2011
The frequency selectivity that characterizes the response of resonant-type metamaterial transmiss... more The frequency selectivity that characterizes the response of resonant-type metamaterial transmission lines lend themselves to their applications in filtering devices. In this paper, it is demonstrated that Complementary Split Ring Resonators (CSRRs) can be used for the design of metamaterial transmission lines. The CSRR is used to design a microstrip stop-band filter for Ultra-Wideband (UWB) applications. In CSRRs the main
2009 IEEE Antennas and Propagation Society International Symposium, 2009
Adaptive antenna arrays have been proposed as a technique to suppress interference and increase s... more Adaptive antenna arrays have been proposed as a technique to suppress interference and increase system capacity. In specialized literature is found extensive studies for the cases of arrays with isotropic elements in adaptive antenna systems. In this paper, we apply dipoles as sensor elements and linear, circular and planar configurations in adaptive antenna arrays of DS-CDMA systems at the base station in the reverse link of cellular communication systems. Computational numerical simulations for the suppression capacity of the considered schemes, used the adaptive algorithm supervised recursive least squares to adjust the weight coefficients of the array are considered. This real scheme of dipole antennas when compared with ideal scheme of isotropic antennas it presented sufficiently reasonable approaches being therefore recommended for applications in real system cellular mobile communications. The comparisons of different geometric adaptive antenna arrays used dipoles as sensor elements are discussed and analyzed. The objective of this study is to present a general analysis of the performance of dipoles (not-isotropic antennas) in adaptive antenna arrays considered linear, circular and planar configurations of sensor elements.
2010 International Workshop on Antenna Technology (iWAT), 2010
Page 1. A New Compact Koch Fractal Patch Antenna on an EBG Ground Plane Elder EC Oliveira(1), Ada... more Page 1. A New Compact Koch Fractal Patch Antenna on an EBG Ground Plane Elder EC Oliveira(1), Adaildo G. D'Assunção*(1), Ronaldo de Andrade Martins (1), and Antonio LPS Campos(2) (1)Federal University of Rio Grande ...
This paper presents a study of implementation procedures for characterization of multi-slot micro... more This paper presents a study of implementation procedures for characterization of multi-slot microstrip patch antennas used for wireless communication systems. An artificial neural network multilayer perceptron is used to locate the bands of operational frequencies of the antenna for different geometries configurations. The antenna is projected, simulated and tested in laboratory. The results obtained are compared in order to validate
2011 SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference (IMOC 2011), 2011
This paper presents the numerical characterization of two RFID tags. The analysis of these struct... more This paper presents the numerical characterization of two RFID tags. The analysis of these structures is made using the WCIP. Are compared the initial results found in literature with those obtained through simulations on WCIP with objective to show that this method is able to analyze such structures. Is shown still, the behavior of electric and magnetic fields, the latter
Digests of the 2010 14th Biennial IEEE Conference on Electromagnetic Field Computation, 2010
An investigation of the bandwidth behavior of planar monopoles built with quasi-fractal patches b... more An investigation of the bandwidth behavior of planar monopoles built with quasi-fractal patches based on the curves of Koch is presented. A rectangular monopole patch microstrip antenna is used as reference and generator for the proposed quasi-fractals antennas. Koch levels 1 and 2 geometries are developed. The analysis of the antenna structures is performed using Ansoft HFSS™. Prototypes are built
The 8th European Conference on Antennas and Propagation (EuCAP 2014), 2014
In this work, a new ultra wide band circular ring patch antenna is proposed for spectral sensing ... more In this work, a new ultra wide band circular ring patch antenna is proposed for spectral sensing application as well as the transmission and reception of radiofrequency in cognitive radio systems. The proposed structure has simple design and easy construction, making it reconfigurable by enabling or disabling the parasitic elements coplanar to the antenna. Simulation and measurements results confirm good agreement and adequate antenna response in the frequency range from 3.1 GHz to 10.6 GHz, in terms of the reflection coefficient and radiation pattern, validating the applicability of the proposed structure for cognitive radio systems front-end.
O anel hibrido Rat-Race e um dispositivo acoplador de potencia de quatro portas com muitas aplica... more O anel hibrido Rat-Race e um dispositivo acoplador de potencia de quatro portas com muitas aplicacoes em circuitos de comunicacao para a faixa de micro-ondas e de ondas milimetricas. O anel hibrido descrito neste artigo e constituido de quatro secoes de microfita, uma de comprimento ¾λ e tres de comprimento ¼λ. O acoplamento entre as porta 1 e 2 (S12) e as portas 1 e 3 (S13) foram caracterizados com auxilio da ferramenta de analise Ansoft Designer TM , que implementa o metodo dos momentos (MoM). Em particular, foram verificadas as defasagens de sinais na faixa de micro-ondas transmitidos as portas de saida (2 e 3) apos a excitacao do circuito de microfita na porta de entrada 1. Com a finalidade de validar os resultados teoricos simulados, um prototipo do dispositivo foi fabricado e medido no laboratorio do INCTCSF-UFRN (Instituto Nacional de Ciencia e Tecnologia de Comunicacao Sem Fio).
2011 IEEE-APS Topical Conference on Antennas and Propagation in Wireless Communications, 2011
This work presents a study of implementation procedures for multi-slot microstrip patch antennas ... more This work presents a study of implementation procedures for multi-slot microstrip patch antennas characterization for wireless communication systems. An artificial neural network multilayer perceptron is used to locate the bands of operational frequencies of the antenna for different geometrics configurations. The antenna is designed, simulated and measured in laboratory. The obtained results are compared and a good agreement is observed.
SBMO/IEEE MTT-S International Conference on Microwave and Optoelectronics, 2005.
Abstract This work presents an efficient implementation of the 2.5D ray-tracing method for mode... more Abstract This work presents an efficient implementation of the 2.5D ray-tracing method for modeling indoor propagation. The implementation is made by means of graphic software tools using the shooting and bouncing rays (SBR) technique, in combination with the uniform ...
International Journal of Infrared and Millimeter Waves, 2000
A full wave analysis is developed for frequency selective surfaces composed of rectangular patche... more A full wave analysis is developed for frequency selective surfaces composed of rectangular patches mounted on a dielectric anisotropic substrate and covered with a uniaxial anisotropic superstrate. The moment method is used in combination with the spectral domain immittance approach to determine the FSS structure reflection and transmission coefficients.
2011 SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference (IMOC 2011), 2011
The frequency selectivity that characterizes the response of resonant-type metamaterial transmiss... more The frequency selectivity that characterizes the response of resonant-type metamaterial transmission lines lend themselves to their applications in filtering devices. In this paper, it is demonstrated that Complementary Split Ring Resonators (CSRRs) can be used for the design of metamaterial transmission lines. The CSRR is used to design a microstrip stop-band filter for Ultra-Wideband (UWB) applications. In CSRRs the main
2009 IEEE Antennas and Propagation Society International Symposium, 2009
Adaptive antenna arrays have been proposed as a technique to suppress interference and increase s... more Adaptive antenna arrays have been proposed as a technique to suppress interference and increase system capacity. In specialized literature is found extensive studies for the cases of arrays with isotropic elements in adaptive antenna systems. In this paper, we apply dipoles as sensor elements and linear, circular and planar configurations in adaptive antenna arrays of DS-CDMA systems at the base station in the reverse link of cellular communication systems. Computational numerical simulations for the suppression capacity of the considered schemes, used the adaptive algorithm supervised recursive least squares to adjust the weight coefficients of the array are considered. This real scheme of dipole antennas when compared with ideal scheme of isotropic antennas it presented sufficiently reasonable approaches being therefore recommended for applications in real system cellular mobile communications. The comparisons of different geometric adaptive antenna arrays used dipoles as sensor elements are discussed and analyzed. The objective of this study is to present a general analysis of the performance of dipoles (not-isotropic antennas) in adaptive antenna arrays considered linear, circular and planar configurations of sensor elements.
2010 International Workshop on Antenna Technology (iWAT), 2010
Page 1. A New Compact Koch Fractal Patch Antenna on an EBG Ground Plane Elder EC Oliveira(1), Ada... more Page 1. A New Compact Koch Fractal Patch Antenna on an EBG Ground Plane Elder EC Oliveira(1), Adaildo G. D'Assunção*(1), Ronaldo de Andrade Martins (1), and Antonio LPS Campos(2) (1)Federal University of Rio Grande ...
This paper presents a study of implementation procedures for characterization of multi-slot micro... more This paper presents a study of implementation procedures for characterization of multi-slot microstrip patch antennas used for wireless communication systems. An artificial neural network multilayer perceptron is used to locate the bands of operational frequencies of the antenna for different geometries configurations. The antenna is projected, simulated and tested in laboratory. The results obtained are compared in order to validate
2011 SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference (IMOC 2011), 2011
This paper presents the numerical characterization of two RFID tags. The analysis of these struct... more This paper presents the numerical characterization of two RFID tags. The analysis of these structures is made using the WCIP. Are compared the initial results found in literature with those obtained through simulations on WCIP with objective to show that this method is able to analyze such structures. Is shown still, the behavior of electric and magnetic fields, the latter
Digests of the 2010 14th Biennial IEEE Conference on Electromagnetic Field Computation, 2010
An investigation of the bandwidth behavior of planar monopoles built with quasi-fractal patches b... more An investigation of the bandwidth behavior of planar monopoles built with quasi-fractal patches based on the curves of Koch is presented. A rectangular monopole patch microstrip antenna is used as reference and generator for the proposed quasi-fractals antennas. Koch levels 1 and 2 geometries are developed. The analysis of the antenna structures is performed using Ansoft HFSS™. Prototypes are built
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Papers by Adaildo Assuncao