Hadi Aliakbarian - Academia.edu (original) (raw)
Papers by Hadi Aliakbarian
IET Microwaves, Antennas & Propagation, 2022
Analogue versus digital for baseband beam steerable array used for LEO satellite applications
یلک د گژاو نا : مودار یسانشاوه رادار لنپ چیودناس شنامک جاوما یروبع تفا هدیکچ ششوپ بآ طیارش اب ییو... more یلک د گژاو نا : مودار یسانشاوه رادار لنپ چیودناس شنامک جاوما یروبع تفا هدیکچ ششوپ بآ طیارش اب ییورایور یارب یتارباخم یاه هتفای هعسوت یسیطانغمورتکلا تیفافش نیرتشیب اب و تخس ییاوه و ربارب رد هلباقم .دنا یاهداب 220 یدرکلمع ییامد طیارش ،تعاس رب رتمولیک -40 ات 60 یتناس هجرد تبوطر ،دارگ 90% ، شبات تفا تیاهن رد و شفنبارف جاوما زا رتمک یسیطانغمورتکلا جاوما یروبع 0.3 یسد زا رتمک شبطق ود یارب یروبع تفا فلاتخا و لب 0.05 یسد هدمع زا لب تامازلا نیرت مودار اب طبترم یحارط تست و یسدنهم یحارط هلاقم نیا رد .تسا یسانشاوه یتارباخم یاه هنومن نیلوا یور یبرجت یاه مودار زا دناب یسانشاوه رادار یارب یچیودناس C تست هارمه هب طانغمورتکلا یاه لنپ هب طوبرم شنامک تست و یسی تامازلا .تسا هدش لیصفت اه هدش تباجا داوم باختنا اب یطیحم سوکابآ رازفا مرن رد دودحم ناملا یزاس هیبش اب یکیناکم یرادیاپ یبایزرا .دنا 6.12 و شنامک تست و هرهب یبایزرا جیاتن .تسا هدش یبایزرا یسیطانغمورتکلا تست اب یسیطانغمورتکلا یرو یم ناشن شنامک تست هدش هتخاس راتخاس هک دهد یم شنامک راب ات دناوت 190 هب ار نتوین تست قباطم .دنک لمحت نمیا روط تیدودحم هب ...
11th International Symposium on Antenna Technology and Applied Electromagnetics [ANTEM 2005], 2005
In this paper, the effects of t vector for GPOF approximation of a Green's function for a sin... more In this paper, the effects of t vector for GPOF approximation of a Green's function for a single layered microstrip structure have been evaluated. In order to do this, effects of T0 and dt variations and also the simple polynomial profile of non-uniform sampling strategy have been evaluated. The best value for each computation can be determined separately using different compromising policies between time and accuracy.
The ever increasing use of body-worn systems in the Internet of Things application needs better a... more The ever increasing use of body-worn systems in the Internet of Things application needs better antenna subsystem designs compatible with its requirements. Several challenges limiting the performance of a body-worn system, from materials, and environmental conditions to the e ects of on body application and its hazards are discussed. As a test case, a exible textile Planar Inverted-F antenna is presented and discussed. The choice of this topology is due to its simplicity in design and fabrication, relatively broad bandwidth and the presence of a rear ground plane, which minimizes the impacts of the human body on the antenna performance. It is designed on a felt substrate, whereas Aaronia-shield conductive textile is utilized as its conductive parts (radiator, shorting wall and ground plane). The antenna performance is studied in two cases, rst in free space and then in bent conditions in the close proximity to the human body. The in uence of the relative humidity on the textile ante...
11th International Symposium on Antenna Technology and Applied Electromagnetics [ANTEM 2005], 2005
In this paper, the effects of t vector for GPOF approximation of a Green's function for a sin... more In this paper, the effects of t vector for GPOF approximation of a Green's function for a single layered microstrip structure have been evaluated. In order to do this, effects of T0 and dt variations and also the simple polynomial profile of non-uniform sampling strategy have been evaluated. The best value for each computation can be determined separately using different compromising policies between time and accuracy.
2018 9th International Symposium on Telecommunications (IST), 2018
2020 10th International Symposium onTelecommunications (IST), 2020
Antenna efficiency is one of the most difficult parameters of any antenna to measure. One of the ... more Antenna efficiency is one of the most difficult parameters of any antenna to measure. One of the practical methods of measuring antenna efficiency is the use of Reverberation Chambers (RC), which increases the accuracy of the measurement. In this paper, based on full-wave simulation of a complete reverberation chamber, the efficiency of a horn antenna is obtained by using two methods, one with the reference antenna and the other one without reference antenna. The results show that by increasing the time of measurement, the accuracy increases dramatically. Simulations show that 25 measurement samples are enough to reduce the error to less than 20%. The comparison also confirms that the first method has more accuracy in this example.
2021 29th Iranian Conference on Electrical Engineering (ICEE), 2021
In this paper, a miniaturized implantable circularly polarized Archimedean spiral Planar Inverted... more In this paper, a miniaturized implantable circularly polarized Archimedean spiral Planar Inverted- F Antenna (SPIFA) is presented. The antenna is electrically small, with a volume of π x 5 mm x 5 mm x 2.2 mm and a diameter of 0.03λ. This antenna operates in the ISM frequency band (902.8-928 MHz) and is simulated in a three-layered tissue including skin, fat, and muscle. Characteristics of the proposed structure make it a suitable option for implantable applications. Furthermore, the effects of different parameters include the length of Archimedean spiral, distance from feed to short pin, substrate thickness, dielectric constant, and dielectric loss tangent on bandwidth, resonant frequency, and total efficiency, are analyzed to achieve an acceptable performance for implantable applications in this frequency band. The final antenna has a bandwidth of 25 MHz and a total efficiency of -16 dB.
2015 Loughborough Antennas & Propagation Conference (LAPC), 2015
RF and microwave filters are an undeniable part of electronic and telecommunication systems and a... more RF and microwave filters are an undeniable part of electronic and telecommunication systems and are widely used in receivers, tuners, up/down converters, etc. In this paper, the design procedure and results of an 11-order hairpin band pass filter, with Cauer-Chebyshev response designed at C band is presented. The filter is integrated with a harmonic suppression circuit based on quarter-wavelength short stubs. The short stubs demonstrate a good quality short circuit at harmonic frequencies. Also, because of quarter-wavelength transformer, it present open circuit at passband frequencies and had no significant impact with it. The total circuit has about 1 GHz 3dB-bandwidth at the center frequency of 4.15 GHz (3.65 GHz to 4.65 GHz) which is an ultra wide band for hairpin filters. The return loss of better than -12.3 dB and the insertion loss of 2.2 dB in pass-band are achieved. Also the rejection of filter at 5 GHz is -59.5 dB demonstrating that the stopband response of the filter is excellent. Finally with regard to short-stubs, the harmonic spurious suppression of more than 40 dB is achieved to suppress undesirable frequencies.
2017 International Symposium on Electromagnetic Compatibility - EMC EUROPE, 2017
A modified dipole form of the PICA (planar inverted cone antenna) is presented for EMC measuremen... more A modified dipole form of the PICA (planar inverted cone antenna) is presented for EMC measurements in this communication. By simply getting the whole structure halved, a further step towards miniaturization has been taken. The half-cut antenna shows over a decade impedance bandwidth while offering a 50% reduction in the size compared to the full version and having stable directional radiation pattern. The performance and characteristics of the antenna are investigated through both simulation and measurement.
Electrical Engineering (ICEE), Iranian Conference on, 2018
Material composition and fabrication procedure are among the most influential parameters affectin... more Material composition and fabrication procedure are among the most influential parameters affecting radome performance. The main goal of this paper is to design and implement an A-type sandwich panel, with an insertion loss of 0.3dB and an attenuation difference of less than 0.05dB between horizontal and vertical polarizations with more than 200MHz bandwidth in C-band. Prototypes are made by two methods of hand-lay-up and by using a vacuum bagging process. Two types of A-type panel sandwiches, called panel A and panel B, have designed and manufactured which are different in terms of material, thickness, and method of production. Their respective electromagnetic and mechanical conditions are investigated. Panel A passes the mentioned electromagnetic requirements. However for panel B, its vertical and horizontal insertion losses are greater than 0.3dB in 5.6GHz, and the polarization difference is not acceptable in the most of the operation band. Investigating the strength of each panel, the highest wind load calculated from the measurement results are 190 and 370 N for panel A and B, respectively.
IEEE Transactions on Instrumentation and Measurement, 2022
IEEE Transactions on Microwave Theory and Techniques, 2013
ABSTRACT A smart wearable textile array system (SWTAS) with direction of arrival (DoA) estimation... more ABSTRACT A smart wearable textile array system (SWTAS) with direction of arrival (DoA) estimation and beamforming is proposed and developed for biomedical telemetry applications. This conformal system enables effective and continuous patient monitoring when combined with one or more health sensors, as information about the subject's health condition is received adap-tively to guarantee link reliability. This operation is facilitated by a receiver front-end and a digital baseband beamforming network, which enables scalability and flexibility. The proposed SWTAS also features flexible antenna arrays made using textiles, which are arbitrarily located on a cylindrically shaped body phantom to ensure wide spatial DoA estimation capability. Besides being designed to suit on-body placement, the system performance is also characterized for on-body usage using a commercial body-emulating liquid, and placed at a realistic distance from the body, considering user clothing. Investigation indicated a good performance in the system's 80 forward plane with a DoA accuracy of 3 . Finally, a practical evaluation is presented using two transmitters placed at distinct locations and distances. The system successfully estimated both DoAs and received the telemetry signals using beamforming.
IEEE Transactions on Microwave Theory and Techniques, 2013
IEEE Transactions on Education, 2014
IEEE Transactions on Antennas and Propagation, 2009
... An Effective Technique for Symmetric Planar Monopole Antenna Miniaturization Soheil Radiom, A... more ... An Effective Technique for Symmetric Planar Monopole Antenna Miniaturization Soheil Radiom, Associate Member, IEEE, Hadi Aliakbarian, Member, IEEE, Guy AE Vandenbosch, Senior Member, IEEE, and Georges GE Gielen, Fellow, IEEE ... [17] S. Radiom, M. Baghaei-Nejad, G ...
IEEE Transactions on Antennas and Propagation, 2009
... Performance Xue Ni Low, Zhi Ning Chen, Terence SP See Institute for Infocomm Research 1 Fusio... more ... Performance Xue Ni Low, Zhi Ning Chen, Terence SP See Institute for Infocomm Research 1 Fusionopolis Way, #21-01 Connexis, Singapore 138632 E-mails: lowx0001@ntu.edu. sg; chenzn@i2r.a-star.edu.sg; spsee@i2r.a-star.edu.sg Abstract ...
IEEE Transactions on Antennas and Propagation, 2009
Forecast of biological consequences of climate changes depend on both long-term observations and ... more Forecast of biological consequences of climate changes depend on both long-term observations and the establishment of carbon budgets within pelagic ecosystems, including the assessment of biomasses and activities of all players in the global carbon cycle. Approximately 25% of oceanic primary happen over continental shelves, so these are important sites for studies of global carbon dynamics. The Brazilian Continental Shelf (BCS) has sparse and non-systematic in situ information on phytoplankton biomass, making products derived from ocean color remote sensing extremely valuable. This work analyzes chlorophyll concentration (Chl) estimated from four ocean color sensors (CZCS, OCTS, SeaWiFS and MODIS) over the BCS, to compare Chl and annual cycles meridionally. Also, useful complementary ocean color variables are presented. Chl gradients increased from the central region towards north and south, limited by estuarine plumes of Amazon and La Plata rivers, and clear annual Chl cycles appear in most areas. In southern and central areas, annual cycles show strong seasonal variability while interannual and long-term variability are equally important in the remaining areas. This is the first comparative evaluation of the Chl over the BCS and will aid the understanding of its long-term variability; essential initial step for discussions of climate changes.
IEEE Antennas and Wireless Propagation Letters, 2008
ABSTRACT Two new electrically small spherical antennas are presented in this letter. The antennas... more ABSTRACT Two new electrically small spherical antennas are presented in this letter. The antennas have perpendicular arms to reduce radiation cancellation. While having low resonant frequency and high radiation efficiency, the radiation patterns of the antennas are almost isotropic. The proposed folded spherical wire antenna (SWA) shows approximately 50-Omega radiation resistance which eliminates the need for using a matching circuit for antenna feeding. Moreover, the proposed folded SWA is fabricated to verify simulation results. An attempt has been made to approach the fundamental limitations of small antennas for better characteristics while keeping the size as small as possible.
IET Microwaves, Antennas & Propagation, 2022
Analogue versus digital for baseband beam steerable array used for LEO satellite applications
یلک د گژاو نا : مودار یسانشاوه رادار لنپ چیودناس شنامک جاوما یروبع تفا هدیکچ ششوپ بآ طیارش اب ییو... more یلک د گژاو نا : مودار یسانشاوه رادار لنپ چیودناس شنامک جاوما یروبع تفا هدیکچ ششوپ بآ طیارش اب ییورایور یارب یتارباخم یاه هتفای هعسوت یسیطانغمورتکلا تیفافش نیرتشیب اب و تخس ییاوه و ربارب رد هلباقم .دنا یاهداب 220 یدرکلمع ییامد طیارش ،تعاس رب رتمولیک -40 ات 60 یتناس هجرد تبوطر ،دارگ 90% ، شبات تفا تیاهن رد و شفنبارف جاوما زا رتمک یسیطانغمورتکلا جاوما یروبع 0.3 یسد زا رتمک شبطق ود یارب یروبع تفا فلاتخا و لب 0.05 یسد هدمع زا لب تامازلا نیرت مودار اب طبترم یحارط تست و یسدنهم یحارط هلاقم نیا رد .تسا یسانشاوه یتارباخم یاه هنومن نیلوا یور یبرجت یاه مودار زا دناب یسانشاوه رادار یارب یچیودناس C تست هارمه هب طانغمورتکلا یاه لنپ هب طوبرم شنامک تست و یسی تامازلا .تسا هدش لیصفت اه هدش تباجا داوم باختنا اب یطیحم سوکابآ رازفا مرن رد دودحم ناملا یزاس هیبش اب یکیناکم یرادیاپ یبایزرا .دنا 6.12 و شنامک تست و هرهب یبایزرا جیاتن .تسا هدش یبایزرا یسیطانغمورتکلا تست اب یسیطانغمورتکلا یرو یم ناشن شنامک تست هدش هتخاس راتخاس هک دهد یم شنامک راب ات دناوت 190 هب ار نتوین تست قباطم .دنک لمحت نمیا روط تیدودحم هب ...
11th International Symposium on Antenna Technology and Applied Electromagnetics [ANTEM 2005], 2005
In this paper, the effects of t vector for GPOF approximation of a Green's function for a sin... more In this paper, the effects of t vector for GPOF approximation of a Green's function for a single layered microstrip structure have been evaluated. In order to do this, effects of T0 and dt variations and also the simple polynomial profile of non-uniform sampling strategy have been evaluated. The best value for each computation can be determined separately using different compromising policies between time and accuracy.
The ever increasing use of body-worn systems in the Internet of Things application needs better a... more The ever increasing use of body-worn systems in the Internet of Things application needs better antenna subsystem designs compatible with its requirements. Several challenges limiting the performance of a body-worn system, from materials, and environmental conditions to the e ects of on body application and its hazards are discussed. As a test case, a exible textile Planar Inverted-F antenna is presented and discussed. The choice of this topology is due to its simplicity in design and fabrication, relatively broad bandwidth and the presence of a rear ground plane, which minimizes the impacts of the human body on the antenna performance. It is designed on a felt substrate, whereas Aaronia-shield conductive textile is utilized as its conductive parts (radiator, shorting wall and ground plane). The antenna performance is studied in two cases, rst in free space and then in bent conditions in the close proximity to the human body. The in uence of the relative humidity on the textile ante...
11th International Symposium on Antenna Technology and Applied Electromagnetics [ANTEM 2005], 2005
In this paper, the effects of t vector for GPOF approximation of a Green's function for a sin... more In this paper, the effects of t vector for GPOF approximation of a Green's function for a single layered microstrip structure have been evaluated. In order to do this, effects of T0 and dt variations and also the simple polynomial profile of non-uniform sampling strategy have been evaluated. The best value for each computation can be determined separately using different compromising policies between time and accuracy.
2018 9th International Symposium on Telecommunications (IST), 2018
2020 10th International Symposium onTelecommunications (IST), 2020
Antenna efficiency is one of the most difficult parameters of any antenna to measure. One of the ... more Antenna efficiency is one of the most difficult parameters of any antenna to measure. One of the practical methods of measuring antenna efficiency is the use of Reverberation Chambers (RC), which increases the accuracy of the measurement. In this paper, based on full-wave simulation of a complete reverberation chamber, the efficiency of a horn antenna is obtained by using two methods, one with the reference antenna and the other one without reference antenna. The results show that by increasing the time of measurement, the accuracy increases dramatically. Simulations show that 25 measurement samples are enough to reduce the error to less than 20%. The comparison also confirms that the first method has more accuracy in this example.
2021 29th Iranian Conference on Electrical Engineering (ICEE), 2021
In this paper, a miniaturized implantable circularly polarized Archimedean spiral Planar Inverted... more In this paper, a miniaturized implantable circularly polarized Archimedean spiral Planar Inverted- F Antenna (SPIFA) is presented. The antenna is electrically small, with a volume of π x 5 mm x 5 mm x 2.2 mm and a diameter of 0.03λ. This antenna operates in the ISM frequency band (902.8-928 MHz) and is simulated in a three-layered tissue including skin, fat, and muscle. Characteristics of the proposed structure make it a suitable option for implantable applications. Furthermore, the effects of different parameters include the length of Archimedean spiral, distance from feed to short pin, substrate thickness, dielectric constant, and dielectric loss tangent on bandwidth, resonant frequency, and total efficiency, are analyzed to achieve an acceptable performance for implantable applications in this frequency band. The final antenna has a bandwidth of 25 MHz and a total efficiency of -16 dB.
2015 Loughborough Antennas & Propagation Conference (LAPC), 2015
RF and microwave filters are an undeniable part of electronic and telecommunication systems and a... more RF and microwave filters are an undeniable part of electronic and telecommunication systems and are widely used in receivers, tuners, up/down converters, etc. In this paper, the design procedure and results of an 11-order hairpin band pass filter, with Cauer-Chebyshev response designed at C band is presented. The filter is integrated with a harmonic suppression circuit based on quarter-wavelength short stubs. The short stubs demonstrate a good quality short circuit at harmonic frequencies. Also, because of quarter-wavelength transformer, it present open circuit at passband frequencies and had no significant impact with it. The total circuit has about 1 GHz 3dB-bandwidth at the center frequency of 4.15 GHz (3.65 GHz to 4.65 GHz) which is an ultra wide band for hairpin filters. The return loss of better than -12.3 dB and the insertion loss of 2.2 dB in pass-band are achieved. Also the rejection of filter at 5 GHz is -59.5 dB demonstrating that the stopband response of the filter is excellent. Finally with regard to short-stubs, the harmonic spurious suppression of more than 40 dB is achieved to suppress undesirable frequencies.
2017 International Symposium on Electromagnetic Compatibility - EMC EUROPE, 2017
A modified dipole form of the PICA (planar inverted cone antenna) is presented for EMC measuremen... more A modified dipole form of the PICA (planar inverted cone antenna) is presented for EMC measurements in this communication. By simply getting the whole structure halved, a further step towards miniaturization has been taken. The half-cut antenna shows over a decade impedance bandwidth while offering a 50% reduction in the size compared to the full version and having stable directional radiation pattern. The performance and characteristics of the antenna are investigated through both simulation and measurement.
Electrical Engineering (ICEE), Iranian Conference on, 2018
Material composition and fabrication procedure are among the most influential parameters affectin... more Material composition and fabrication procedure are among the most influential parameters affecting radome performance. The main goal of this paper is to design and implement an A-type sandwich panel, with an insertion loss of 0.3dB and an attenuation difference of less than 0.05dB between horizontal and vertical polarizations with more than 200MHz bandwidth in C-band. Prototypes are made by two methods of hand-lay-up and by using a vacuum bagging process. Two types of A-type panel sandwiches, called panel A and panel B, have designed and manufactured which are different in terms of material, thickness, and method of production. Their respective electromagnetic and mechanical conditions are investigated. Panel A passes the mentioned electromagnetic requirements. However for panel B, its vertical and horizontal insertion losses are greater than 0.3dB in 5.6GHz, and the polarization difference is not acceptable in the most of the operation band. Investigating the strength of each panel, the highest wind load calculated from the measurement results are 190 and 370 N for panel A and B, respectively.
IEEE Transactions on Instrumentation and Measurement, 2022
IEEE Transactions on Microwave Theory and Techniques, 2013
ABSTRACT A smart wearable textile array system (SWTAS) with direction of arrival (DoA) estimation... more ABSTRACT A smart wearable textile array system (SWTAS) with direction of arrival (DoA) estimation and beamforming is proposed and developed for biomedical telemetry applications. This conformal system enables effective and continuous patient monitoring when combined with one or more health sensors, as information about the subject's health condition is received adap-tively to guarantee link reliability. This operation is facilitated by a receiver front-end and a digital baseband beamforming network, which enables scalability and flexibility. The proposed SWTAS also features flexible antenna arrays made using textiles, which are arbitrarily located on a cylindrically shaped body phantom to ensure wide spatial DoA estimation capability. Besides being designed to suit on-body placement, the system performance is also characterized for on-body usage using a commercial body-emulating liquid, and placed at a realistic distance from the body, considering user clothing. Investigation indicated a good performance in the system's 80 forward plane with a DoA accuracy of 3 . Finally, a practical evaluation is presented using two transmitters placed at distinct locations and distances. The system successfully estimated both DoAs and received the telemetry signals using beamforming.
IEEE Transactions on Microwave Theory and Techniques, 2013
IEEE Transactions on Education, 2014
IEEE Transactions on Antennas and Propagation, 2009
... An Effective Technique for Symmetric Planar Monopole Antenna Miniaturization Soheil Radiom, A... more ... An Effective Technique for Symmetric Planar Monopole Antenna Miniaturization Soheil Radiom, Associate Member, IEEE, Hadi Aliakbarian, Member, IEEE, Guy AE Vandenbosch, Senior Member, IEEE, and Georges GE Gielen, Fellow, IEEE ... [17] S. Radiom, M. Baghaei-Nejad, G ...
IEEE Transactions on Antennas and Propagation, 2009
... Performance Xue Ni Low, Zhi Ning Chen, Terence SP See Institute for Infocomm Research 1 Fusio... more ... Performance Xue Ni Low, Zhi Ning Chen, Terence SP See Institute for Infocomm Research 1 Fusionopolis Way, #21-01 Connexis, Singapore 138632 E-mails: lowx0001@ntu.edu. sg; chenzn@i2r.a-star.edu.sg; spsee@i2r.a-star.edu.sg Abstract ...
IEEE Transactions on Antennas and Propagation, 2009
Forecast of biological consequences of climate changes depend on both long-term observations and ... more Forecast of biological consequences of climate changes depend on both long-term observations and the establishment of carbon budgets within pelagic ecosystems, including the assessment of biomasses and activities of all players in the global carbon cycle. Approximately 25% of oceanic primary happen over continental shelves, so these are important sites for studies of global carbon dynamics. The Brazilian Continental Shelf (BCS) has sparse and non-systematic in situ information on phytoplankton biomass, making products derived from ocean color remote sensing extremely valuable. This work analyzes chlorophyll concentration (Chl) estimated from four ocean color sensors (CZCS, OCTS, SeaWiFS and MODIS) over the BCS, to compare Chl and annual cycles meridionally. Also, useful complementary ocean color variables are presented. Chl gradients increased from the central region towards north and south, limited by estuarine plumes of Amazon and La Plata rivers, and clear annual Chl cycles appear in most areas. In southern and central areas, annual cycles show strong seasonal variability while interannual and long-term variability are equally important in the remaining areas. This is the first comparative evaluation of the Chl over the BCS and will aid the understanding of its long-term variability; essential initial step for discussions of climate changes.
IEEE Antennas and Wireless Propagation Letters, 2008
ABSTRACT Two new electrically small spherical antennas are presented in this letter. The antennas... more ABSTRACT Two new electrically small spherical antennas are presented in this letter. The antennas have perpendicular arms to reduce radiation cancellation. While having low resonant frequency and high radiation efficiency, the radiation patterns of the antennas are almost isotropic. The proposed folded spherical wire antenna (SWA) shows approximately 50-Omega radiation resistance which eliminates the need for using a matching circuit for antenna feeding. Moreover, the proposed folded SWA is fabricated to verify simulation results. An attempt has been made to approach the fundamental limitations of small antennas for better characteristics while keeping the size as small as possible.