Pub Date : 2011-10-01DOI: 10.1109/IMOC.2011.6169281
M. Alves, L. C. Folgueras, M. C. Rezende
Wind turbines are devices which usually have a large surface area. The combination of effects related to the large surface area and properties of the materials used in their construction can make a wind turbine an important reflector of radar waves, which may interfere with the proper operation of civilian and military radars. There are several possible methods to reduce the radar cross section (RCS) of a wind turbine; here we simulated the effects of a composite microwave absorbent material that can be used to coat or as structural elements of the wind turbine. This material can absorb up to 95% of the energy of the incident wave. Simulations were carried out at 10 GHz (X-band). The use of the absorbent material can significantly reduce the RCS of the wind turbine. The simulations also indicated which parts of the wind turbine contribute more to the reflection of radar waves.
{"title":"Reduction of the radar cross section of a wind turbine using a microwave absorbing material","authors":"M. Alves, L. C. Folgueras, M. C. Rezende","doi":"10.1109/IMOC.2011.6169281","DOIUrl":"https://doi.org/10.1109/IMOC.2011.6169281","url":null,"abstract":"Wind turbines are devices which usually have a large surface area. The combination of effects related to the large surface area and properties of the materials used in their construction can make a wind turbine an important reflector of radar waves, which may interfere with the proper operation of civilian and military radars. There are several possible methods to reduce the radar cross section (RCS) of a wind turbine; here we simulated the effects of a composite microwave absorbent material that can be used to coat or as structural elements of the wind turbine. This material can absorb up to 95% of the energy of the incident wave. Simulations were carried out at 10 GHz (X-band). The use of the absorbent material can significantly reduce the RCS of the wind turbine. The simulations also indicated which parts of the wind turbine contribute more to the reflection of radar waves.","PeriodicalId":179351,"journal":{"name":"2011 SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference (IMOC 2011)","volume":"100 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124787045","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-10-01DOI: 10.1109/IMOC.2011.6169360
A. N. da Silva, F. M. Pontes, L. de Oliveira, J. C. e Silva, A. Neto
The use of FSS with non fractal geometry is proposed in this work. When non fractal details are applied to rectangular patch, the FSS frequency response can be drastically affected. The frequency of resonance can be reduced and new resonance can be obtained. Furthermore, the bandwidth between resonances can be modified. Then, these characteristics can be utilized to design FSS with multiband operations or to reduce the FSS dimensions. In this work, numerical results, obtained using the WCIP method, are presented and discussed to different FSS with non fractal geometry. Two FSS with non fractal geometry are characterized experimentally and the obtained results compared to numerical ones. The results indicate the potential of the non fractal geometry in the FSS design, which instigate the research for new applications.
{"title":"Frequency selective surfaces with non fractal geometry","authors":"A. N. da Silva, F. M. Pontes, L. de Oliveira, J. C. e Silva, A. Neto","doi":"10.1109/IMOC.2011.6169360","DOIUrl":"https://doi.org/10.1109/IMOC.2011.6169360","url":null,"abstract":"The use of FSS with non fractal geometry is proposed in this work. When non fractal details are applied to rectangular patch, the FSS frequency response can be drastically affected. The frequency of resonance can be reduced and new resonance can be obtained. Furthermore, the bandwidth between resonances can be modified. Then, these characteristics can be utilized to design FSS with multiband operations or to reduce the FSS dimensions. In this work, numerical results, obtained using the WCIP method, are presented and discussed to different FSS with non fractal geometry. Two FSS with non fractal geometry are characterized experimentally and the obtained results compared to numerical ones. The results indicate the potential of the non fractal geometry in the FSS design, which instigate the research for new applications.","PeriodicalId":179351,"journal":{"name":"2011 SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference (IMOC 2011)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124245098","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-10-01DOI: 10.1109/IMOC.2011.6169343
L. C. Barbosa, R. D. de Araujo
This paper shows the viability of using inexpensive continuous light sources on Optical Coherence Tomography. Incandescent lamp and sunlight were applied to develop an imaging system with 2 μm of resolution (2 times better than ones commercially available). Therefore it was designed and built a sunlight collector with a tracking module included and a spectral domain optical coherence tomography imaging system. It was verified that low fluctuations of the solar spectrum intensity allow the use of this natural source on imaging systems.
{"title":"Continuous ultra-broadband light sources for Optical Coherence Tomography","authors":"L. C. Barbosa, R. D. de Araujo","doi":"10.1109/IMOC.2011.6169343","DOIUrl":"https://doi.org/10.1109/IMOC.2011.6169343","url":null,"abstract":"This paper shows the viability of using inexpensive continuous light sources on Optical Coherence Tomography. Incandescent lamp and sunlight were applied to develop an imaging system with 2 μm of resolution (2 times better than ones commercially available). Therefore it was designed and built a sunlight collector with a tracking module included and a spectral domain optical coherence tomography imaging system. It was verified that low fluctuations of the solar spectrum intensity allow the use of this natural source on imaging systems.","PeriodicalId":179351,"journal":{"name":"2011 SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference (IMOC 2011)","volume":"07 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123344657","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-10-01DOI: 10.1109/IMOC.2011.6169347
J. Diniz, E. S. Rosa, V. Ribeiro, Julio Oliveira, A. Bordonalli
We propose a hardware-efficient, feed-forward, wide-range frequency offset estimator for DSP-based optical coherent receivers, employed in 112 Gb/s PM-QPSK systems. This estimator is capable to estimate offsets in a range of ±5 GHz, using a simple relationship of signal spectrum. The obtained results show that this estimator is robust to spectrum asymmetry caused by electrical and optical filtering of the signal, even when using return-to-zero signals.
{"title":"Wide-range frequency offset estimator for DSP-based optical coherent receivers","authors":"J. Diniz, E. S. Rosa, V. Ribeiro, Julio Oliveira, A. Bordonalli","doi":"10.1109/IMOC.2011.6169347","DOIUrl":"https://doi.org/10.1109/IMOC.2011.6169347","url":null,"abstract":"We propose a hardware-efficient, feed-forward, wide-range frequency offset estimator for DSP-based optical coherent receivers, employed in 112 Gb/s PM-QPSK systems. This estimator is capable to estimate offsets in a range of ±5 GHz, using a simple relationship of signal spectrum. The obtained results show that this estimator is robust to spectrum asymmetry caused by electrical and optical filtering of the signal, even when using return-to-zero signals.","PeriodicalId":179351,"journal":{"name":"2011 SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference (IMOC 2011)","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121393645","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-10-01DOI: 10.1109/IMOC.2011.6169364
N. Ribeiro, C. Gallep, E. Conforti
A Data eraser/rewriter based on the ultra-long semiconductor optical amplifier (UL-SOA) gain saturation is a new technique able to erase amplitude modulation signal at high bit rates with high extinction ratio. However the main drawback of this technique is the spectral broadening which occurs after the erasure, being the UL-SOA self-phase modulation the effect responsible for this. Therefore, experimental analysis of this spectral broadening is presented. The influence of some parameters is analyzed. The major spectral broadening measured was 1.8 nm, being a problem in WDM applications. Moreover, it is presented a discussion about how the spectral broadening can be prejudicial as well as how to reduce this drawback.
{"title":"Experimental analysis of the spectral broadening in a data eraser/rewriter based on a saturated UL-SOA","authors":"N. Ribeiro, C. Gallep, E. Conforti","doi":"10.1109/IMOC.2011.6169364","DOIUrl":"https://doi.org/10.1109/IMOC.2011.6169364","url":null,"abstract":"A Data eraser/rewriter based on the ultra-long semiconductor optical amplifier (UL-SOA) gain saturation is a new technique able to erase amplitude modulation signal at high bit rates with high extinction ratio. However the main drawback of this technique is the spectral broadening which occurs after the erasure, being the UL-SOA self-phase modulation the effect responsible for this. Therefore, experimental analysis of this spectral broadening is presented. The influence of some parameters is analyzed. The major spectral broadening measured was 1.8 nm, being a problem in WDM applications. Moreover, it is presented a discussion about how the spectral broadening can be prejudicial as well as how to reduce this drawback.","PeriodicalId":179351,"journal":{"name":"2011 SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference (IMOC 2011)","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116279491","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-10-01DOI: 10.1109/IMOC.2011.6169345
E. S. Azevedo, B. D. de Oliveira, M. T. de Melo
A 3-dB microstrip power divider was designed and fabricated to integrate two multi-band-stop filters for Instantaneous Frequency Measurement (IFM) system application. A 2-bits IFM system was set up with the divider. Experimental results are also presented.
{"title":"Microstrip power divider for integration of an Instantaneous Frequency Measurement system","authors":"E. S. Azevedo, B. D. de Oliveira, M. T. de Melo","doi":"10.1109/IMOC.2011.6169345","DOIUrl":"https://doi.org/10.1109/IMOC.2011.6169345","url":null,"abstract":"A 3-dB microstrip power divider was designed and fabricated to integrate two multi-band-stop filters for Instantaneous Frequency Measurement (IFM) system application. A 2-bits IFM system was set up with the divider. Experimental results are also presented.","PeriodicalId":179351,"journal":{"name":"2011 SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference (IMOC 2011)","volume":"142 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124336045","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-10-01DOI: 10.1109/IMOC.2011.6169297
C. E. Rubio-Mercedes, I. T. Lima, H. Hernández-Figueroa, V. Rodriguez‐Esquerre
A numerical analysis of periodic segmented waveguides (PSWs) using the well known technique of two dimensional finite element method (2D-FEM) in the frequency domain is presented. Unlike photonic crystal waveguides (PCWs), light confinement in a PSW is due to total internal reflection as in a continuous waveguide (CWG). Moreover, the dispersion relation of the guided modes in PSW is strongly influenced by the dielectric periodicity along the waveguide. We calculate the mode profile of the PSW in a region far away from the band gap and compare with the mode profile of their equivalent CWG with an averaged refractive index contrast (Δneq).
{"title":"Periodic segmented waveguide analysis by using the 2D finite element method","authors":"C. E. Rubio-Mercedes, I. T. Lima, H. Hernández-Figueroa, V. Rodriguez‐Esquerre","doi":"10.1109/IMOC.2011.6169297","DOIUrl":"https://doi.org/10.1109/IMOC.2011.6169297","url":null,"abstract":"A numerical analysis of periodic segmented waveguides (PSWs) using the well known technique of two dimensional finite element method (2D-FEM) in the frequency domain is presented. Unlike photonic crystal waveguides (PCWs), light confinement in a PSW is due to total internal reflection as in a continuous waveguide (CWG). Moreover, the dispersion relation of the guided modes in PSW is strongly influenced by the dielectric periodicity along the waveguide. We calculate the mode profile of the PSW in a region far away from the band gap and compare with the mode profile of their equivalent CWG with an averaged refractive index contrast (Δneq).","PeriodicalId":179351,"journal":{"name":"2011 SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference (IMOC 2011)","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127709115","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-10-01DOI: 10.1109/IMOC.2011.6169274
J. Monteiro, L. Costa, M. Valente, T. Santos, J. Sousa
Microwave heating has been widely used in the industry to synthesize dielectric materials, in which conventional procedures are slow, expensive and inefficient. In this application, the energy is introduced directly into the volume of the dielectric and as consequence the quality of the process is highly dependent on the uniformity of the electromagnetic field distribution along the material. That is, the non uniformity of the heating is a potential problem with serious consequences. Thermal runaway is the most critical, in materials with temperature dependent dielectric properties. As the material absorbs electromagnetic energy, the temperature increases as does its ability to absorb more energy. To understand this phenomenon, a perceptive of how electromagnetic field propagates and is absorbed by materials is essential, and then we carried out the 3D electromagnetic field simulation in a microwave oven loaded with ceramic samples, changing several parameters, as size, shape and position of the material, magnetron frequency and dielectric properties of the load.
{"title":"Simulating the electromagnetic field in microwave ovens","authors":"J. Monteiro, L. Costa, M. Valente, T. Santos, J. Sousa","doi":"10.1109/IMOC.2011.6169274","DOIUrl":"https://doi.org/10.1109/IMOC.2011.6169274","url":null,"abstract":"Microwave heating has been widely used in the industry to synthesize dielectric materials, in which conventional procedures are slow, expensive and inefficient. In this application, the energy is introduced directly into the volume of the dielectric and as consequence the quality of the process is highly dependent on the uniformity of the electromagnetic field distribution along the material. That is, the non uniformity of the heating is a potential problem with serious consequences. Thermal runaway is the most critical, in materials with temperature dependent dielectric properties. As the material absorbs electromagnetic energy, the temperature increases as does its ability to absorb more energy. To understand this phenomenon, a perceptive of how electromagnetic field propagates and is absorbed by materials is essential, and then we carried out the 3D electromagnetic field simulation in a microwave oven loaded with ceramic samples, changing several parameters, as size, shape and position of the material, magnetron frequency and dielectric properties of the load.","PeriodicalId":179351,"journal":{"name":"2011 SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference (IMOC 2011)","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126470488","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-10-01DOI: 10.1109/IMOC.2011.6169365
J. Rebola, A. Cartaxo
A new method based on the moment generating function (MGF) is proposed to evaluate the performance of an orthogonal frequency division multiplexing (OFDM) system with optical preamplification and direct-detection at the optical receiver, which takes into account arbitrary optical and electrical filtering at the optical receiver. The accuracy of the proposed method is investigated by comparison of the bit error probability obtained from the MGF with the estimates obtained from Monte Carlo simulation, for different electrical filter types with various bandwidths and for a different number of OFDM subcarriers. It is shown that the proposed method has a good accuracy, for bandwidths of the electrical filter typically used in optical OFDM systems (larger than the OFDM signal bandwidth).
{"title":"Using the moment generating function for the performance assessment of optically preamplified direct-detection OFDM systems","authors":"J. Rebola, A. Cartaxo","doi":"10.1109/IMOC.2011.6169365","DOIUrl":"https://doi.org/10.1109/IMOC.2011.6169365","url":null,"abstract":"A new method based on the moment generating function (MGF) is proposed to evaluate the performance of an orthogonal frequency division multiplexing (OFDM) system with optical preamplification and direct-detection at the optical receiver, which takes into account arbitrary optical and electrical filtering at the optical receiver. The accuracy of the proposed method is investigated by comparison of the bit error probability obtained from the MGF with the estimates obtained from Monte Carlo simulation, for different electrical filter types with various bandwidths and for a different number of OFDM subcarriers. It is shown that the proposed method has a good accuracy, for bandwidths of the electrical filter typically used in optical OFDM systems (larger than the OFDM signal bandwidth).","PeriodicalId":179351,"journal":{"name":"2011 SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference (IMOC 2011)","volume":"55 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127969813","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-10-01DOI: 10.1109/IMOC.2011.6169267
Tiago Costa de Araujo, A. Campos
This paper shows a quasi-Koch Fractal Shape added into a Interdigital Microstrip Bandpass Filter to improve its spurious rejection without changing the order of filter neither increase its physical dimensions. The Interdigital Filter is first designed based on the SBCD/ITASAT satellite parameters, and then changed to a novel geometry based on the Koch's Curve Fractal with a relationship of 1:4. Both geometries were simulated and measured, and the numerical results, as well as the simulations, show us that the spurious rejection in the transponder operation became better after the addition of the fractal shape.
{"title":"Improving spurious rejection of ITASAT transponder using Interdigital Microstrip Filter with Quasi-Fractal Koch Curve","authors":"Tiago Costa de Araujo, A. Campos","doi":"10.1109/IMOC.2011.6169267","DOIUrl":"https://doi.org/10.1109/IMOC.2011.6169267","url":null,"abstract":"This paper shows a quasi-Koch Fractal Shape added into a Interdigital Microstrip Bandpass Filter to improve its spurious rejection without changing the order of filter neither increase its physical dimensions. The Interdigital Filter is first designed based on the SBCD/ITASAT satellite parameters, and then changed to a novel geometry based on the Koch's Curve Fractal with a relationship of 1:4. Both geometries were simulated and measured, and the numerical results, as well as the simulations, show us that the spurious rejection in the transponder operation became better after the addition of the fractal shape.","PeriodicalId":179351,"journal":{"name":"2011 SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference (IMOC 2011)","volume":"292 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134216469","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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