Pub Date : 2001-09-09DOI: 10.1109/HFPSC.2001.962177
R. Lewenz, P. Filippidis, S. Salous
Future mobile communication systems will offer higher bit rates than are available from present systems. This will consequently increase their susceptibility to multipath propagation. Adaptive antennas with intelligent basestations, which are able to steer the antenna beam, offer a possible measure to minimize the effects of multipath propagation. A necessary input to the development of future basestations will be radio channel characteristics including direction of arrival information. UMIST has been conducting a programme of channel characterisation over a number of years. The paper describes an antenna array for use with the UMIST eight-channel sounder and its calibration for angle of arrival estimation.
{"title":"Antenna array calibration for a multi-channel direction of arrival sounder","authors":"R. Lewenz, P. Filippidis, S. Salous","doi":"10.1109/HFPSC.2001.962177","DOIUrl":"https://doi.org/10.1109/HFPSC.2001.962177","url":null,"abstract":"Future mobile communication systems will offer higher bit rates than are available from present systems. This will consequently increase their susceptibility to multipath propagation. Adaptive antennas with intelligent basestations, which are able to steer the antenna beam, offer a possible measure to minimize the effects of multipath propagation. A necessary input to the development of future basestations will be radio channel characteristics including direction of arrival information. UMIST has been conducting a programme of channel characterisation over a number of years. The paper describes an antenna array for use with the UMIST eight-channel sounder and its calibration for angle of arrival estimation.","PeriodicalId":129428,"journal":{"name":"6th IEEE High Frequency Postgraduate Colloquium (Cat. No.01TH8574)","volume":"122 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124189049","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 : 2001-09-09DOI: 10.1109/HFPSC.2001.962181
H. St Michael, M. Al-Nuaimi, R. Caldeirinha
Mobile wireless service providers operate at microwave frequencies and they are very likely to continue or move up in frequency in the foreseeable future. The large growth in the use of microwave frequency bands for mobile wireless communication poses an increasing risk of vegetation forms attenuating and scattering the transmitted signal. This, in turn, leads to significant signal degradation, increased error rates and loss in the information content of the transmitted signal. Radio system planners need accurate engineering models, which can be used in the prediction of the effects of vegetation forms on radio signals propagating at frequencies above 1 GHz. Vegetation encountered in mobile radio applications, take the form of single trees, line of trees and a body of trees such as a wood or forest. Using a model based on the Radiative Energy Transfer (RET) theory, the vegetation medium can be characterized by four distinct parameters. These are: the absorption cross section per volume /spl sigma//sub A/, the scatter cross section per volume /spl sigma//sub s/, the ratio of the forward-scattered power to the total scattered power /spl alpha/, and the beamwidth of the forward scatter lobe /spl Delta//spl gamma//sub S/. This paper outlines the RET model and presents results of solutions, yielding the excess attenuation of the vegetation medium as a function of distance into the medium. The paper presents a reliable method for evaluating the four parameter (/spl sigma//sub A/, /spl sigma//sub S/, /spl alpha/, /spl Delta//spl gamma//sub S/) using measured results obtained in an orchard. The paper concludes by comparing the RET characterisation with measurements.
{"title":"Radiative energy transfer prediction of excess attenuation of microwave radio signals in a regularly planted orchard","authors":"H. St Michael, M. Al-Nuaimi, R. Caldeirinha","doi":"10.1109/HFPSC.2001.962181","DOIUrl":"https://doi.org/10.1109/HFPSC.2001.962181","url":null,"abstract":"Mobile wireless service providers operate at microwave frequencies and they are very likely to continue or move up in frequency in the foreseeable future. The large growth in the use of microwave frequency bands for mobile wireless communication poses an increasing risk of vegetation forms attenuating and scattering the transmitted signal. This, in turn, leads to significant signal degradation, increased error rates and loss in the information content of the transmitted signal. Radio system planners need accurate engineering models, which can be used in the prediction of the effects of vegetation forms on radio signals propagating at frequencies above 1 GHz. Vegetation encountered in mobile radio applications, take the form of single trees, line of trees and a body of trees such as a wood or forest. Using a model based on the Radiative Energy Transfer (RET) theory, the vegetation medium can be characterized by four distinct parameters. These are: the absorption cross section per volume /spl sigma//sub A/, the scatter cross section per volume /spl sigma//sub s/, the ratio of the forward-scattered power to the total scattered power /spl alpha/, and the beamwidth of the forward scatter lobe /spl Delta//spl gamma//sub S/. This paper outlines the RET model and presents results of solutions, yielding the excess attenuation of the vegetation medium as a function of distance into the medium. The paper presents a reliable method for evaluating the four parameter (/spl sigma//sub A/, /spl sigma//sub S/, /spl alpha/, /spl Delta//spl gamma//sub S/) using measured results obtained in an orchard. The paper concludes by comparing the RET characterisation with measurements.","PeriodicalId":129428,"journal":{"name":"6th IEEE High Frequency Postgraduate Colloquium (Cat. No.01TH8574)","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133679675","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 : 2001-09-09DOI: 10.1109/HFPSC.2001.962196
S. M. Idrus, R. Green
In this article a novel receiver based on Photoparametric Amplifier (PPA), which one of the alternative for receiver detection and amplification techniques is fully described. The PPA mode of operation involves optical detection and amplification within a single device. The amplifier operation is based on nonlinear characteristics of the photodiode and therefore, the mechanism constituting gain is highly nonlinear and different to that in conventional amplifier/mixer chain. It is able to provide selectivity and sensitivity at the same time, as required for wireless optical communications. In the proposed approach, the detector, front-end amplifier and mixer chain, are replaced by a single device, which reduced component count and therefore cost directly. Under optimum test conditions, the research group has demonstrated a power gain of 17 dB over a baseband detector (BW of 25 MHz), with improved noise performance.
{"title":"Photoparametric amplifier for optical wireless communication system","authors":"S. M. Idrus, R. Green","doi":"10.1109/HFPSC.2001.962196","DOIUrl":"https://doi.org/10.1109/HFPSC.2001.962196","url":null,"abstract":"In this article a novel receiver based on Photoparametric Amplifier (PPA), which one of the alternative for receiver detection and amplification techniques is fully described. The PPA mode of operation involves optical detection and amplification within a single device. The amplifier operation is based on nonlinear characteristics of the photodiode and therefore, the mechanism constituting gain is highly nonlinear and different to that in conventional amplifier/mixer chain. It is able to provide selectivity and sensitivity at the same time, as required for wireless optical communications. In the proposed approach, the detector, front-end amplifier and mixer chain, are replaced by a single device, which reduced component count and therefore cost directly. Under optimum test conditions, the research group has demonstrated a power gain of 17 dB over a baseband detector (BW of 25 MHz), with improved noise performance.","PeriodicalId":129428,"journal":{"name":"6th IEEE High Frequency Postgraduate Colloquium (Cat. No.01TH8574)","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127264773","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 : 2001-09-09DOI: 10.1109/HFPSC.2001.962173
A. Zhu, T. Brazil
This paper presents an efficient digital baseband predistortion linearizer to compensate for the nonlinear distortions induced by RF high power amplifiers in wireless communication systems. The proposed approach utilize a fast RLS filtering algorithm based on V-vector algebra and an indirect learning architecture to update the coefficients of a Volterra-based-predistorter. No preliminary identification of the nonlinear characteristics of the HPA, as required by the conventional pth-order inverse methods, is needed with this approach. Simulation results show that high performance and low computational complexity are achieved in nonlinear systems with a TWT-type power amplifier.
{"title":"Adaptive Volterra-based predistorter design for RF high power amplifiers","authors":"A. Zhu, T. Brazil","doi":"10.1109/HFPSC.2001.962173","DOIUrl":"https://doi.org/10.1109/HFPSC.2001.962173","url":null,"abstract":"This paper presents an efficient digital baseband predistortion linearizer to compensate for the nonlinear distortions induced by RF high power amplifiers in wireless communication systems. The proposed approach utilize a fast RLS filtering algorithm based on V-vector algebra and an indirect learning architecture to update the coefficients of a Volterra-based-predistorter. No preliminary identification of the nonlinear characteristics of the HPA, as required by the conventional pth-order inverse methods, is needed with this approach. Simulation results show that high performance and low computational complexity are achieved in nonlinear systems with a TWT-type power amplifier.","PeriodicalId":129428,"journal":{"name":"6th IEEE High Frequency Postgraduate Colloquium (Cat. No.01TH8574)","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116072383","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 : 2001-09-09DOI: 10.1109/HFPSC.2001.962197
M. Chongcheawchamnan, C. Ng, L. D. Robertson
Two miniaturised passive circuits, lumped-distributed Wilkinson divider and the all-ports matched impedance transformer based on Marchand balun are proposed. Applying a shunted input capacitor and RC isolation network, the Wilkinson divider size is arbitrarily reduced. For the all-ports matched Marchand balun, a proposed isolation network has been applied to reduce the whole size. These two circuits were designed and simulated based on 2.5D electromagnetic simulation software package. Excellent results of X-band lumped-distributed Wilkinson and W-band CPW balun were achieved.
{"title":"Miniaturised and multilayer Wilkinson divider and balun for microwave and millimeter-wave applications","authors":"M. Chongcheawchamnan, C. Ng, L. D. Robertson","doi":"10.1109/HFPSC.2001.962197","DOIUrl":"https://doi.org/10.1109/HFPSC.2001.962197","url":null,"abstract":"Two miniaturised passive circuits, lumped-distributed Wilkinson divider and the all-ports matched impedance transformer based on Marchand balun are proposed. Applying a shunted input capacitor and RC isolation network, the Wilkinson divider size is arbitrarily reduced. For the all-ports matched Marchand balun, a proposed isolation network has been applied to reduce the whole size. These two circuits were designed and simulated based on 2.5D electromagnetic simulation software package. Excellent results of X-band lumped-distributed Wilkinson and W-band CPW balun were achieved.","PeriodicalId":129428,"journal":{"name":"6th IEEE High Frequency Postgraduate Colloquium (Cat. No.01TH8574)","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117107241","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 : 2001-09-09DOI: 10.1109/HFPSC.2001.962172
B. Toner, V. Fusco
In this paper, the development of a turnkey, multi-functional measurement system is described. It is electronically reconfigurable and allows for the on-wafer design of an amplifier to a given specification. All primary amplifier measurements can be completed such as S-parameters, minimum noise figure, source/load pull, harmonic power and intermodulation. In addition, real time voltage/current waveforms of the amplifier can be monitored and dynamic loadlines produced. The requirement for more linear amplifiers has also been addressed in this paper with the low frequency feedback technique being implemented for the first time on MOS technology and on-wafer.
{"title":"Measurement based amplifier design","authors":"B. Toner, V. Fusco","doi":"10.1109/HFPSC.2001.962172","DOIUrl":"https://doi.org/10.1109/HFPSC.2001.962172","url":null,"abstract":"In this paper, the development of a turnkey, multi-functional measurement system is described. It is electronically reconfigurable and allows for the on-wafer design of an amplifier to a given specification. All primary amplifier measurements can be completed such as S-parameters, minimum noise figure, source/load pull, harmonic power and intermodulation. In addition, real time voltage/current waveforms of the amplifier can be monitored and dynamic loadlines produced. The requirement for more linear amplifiers has also been addressed in this paper with the low frequency feedback technique being implemented for the first time on MOS technology and on-wafer.","PeriodicalId":129428,"journal":{"name":"6th IEEE High Frequency Postgraduate Colloquium (Cat. No.01TH8574)","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123334877","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 : 2001-09-09DOI: 10.1109/HFPSC.2001.962159
Yuanzhi Li, Michael J. Lancaster
Application of high temperature superconducting (HTS) materials in the communication industry has become attractive in recent years. Mobile communications, radar, radio telescopes and satellite communication links are some of the many applications which use microwave filters made from HTS materials. Most HTS microwave filters reported in the literature were designed for narrow band applications; this is due to recent commercial requirements. However, some astronomy laboratories need to employ a fairly wide band filter for their radio telescope receivers. An HTS filter is ideal for this application because of the low intrinsic insertion loss and steep filter skirts. A fifteenth order Chebyshev HTS band pass filter, designed for Jodrell Bank Observatory, is presented for astronomy applications. Sonnet EM simulation results are provided for this 15-order filter with fractional bandwidth of 26.4%. Good agreement between theoretical results and simulations is obtained. Size miniaturization has also been carried out. Comparisons of simulation results between original and minimized design are also provided.
{"title":"Fifteen pole superconducting filter for radio astronomy","authors":"Yuanzhi Li, Michael J. Lancaster","doi":"10.1109/HFPSC.2001.962159","DOIUrl":"https://doi.org/10.1109/HFPSC.2001.962159","url":null,"abstract":"Application of high temperature superconducting (HTS) materials in the communication industry has become attractive in recent years. Mobile communications, radar, radio telescopes and satellite communication links are some of the many applications which use microwave filters made from HTS materials. Most HTS microwave filters reported in the literature were designed for narrow band applications; this is due to recent commercial requirements. However, some astronomy laboratories need to employ a fairly wide band filter for their radio telescope receivers. An HTS filter is ideal for this application because of the low intrinsic insertion loss and steep filter skirts. A fifteenth order Chebyshev HTS band pass filter, designed for Jodrell Bank Observatory, is presented for astronomy applications. Sonnet EM simulation results are provided for this 15-order filter with fractional bandwidth of 26.4%. Good agreement between theoretical results and simulations is obtained. Size miniaturization has also been carried out. Comparisons of simulation results between original and minimized design are also provided.","PeriodicalId":129428,"journal":{"name":"6th IEEE High Frequency Postgraduate Colloquium (Cat. No.01TH8574)","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131289802","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 : 2001-09-09DOI: 10.1109/HFPSC.2001.962150
David, Williams, P. Tasker
A fully automated electronic load and source pull measurement system has been developed using standard Agilent ESG Frequency sources. Combined with a vector corrected time-domain waveform measurement system based on the HP-MTA (Microwave Transition Analyser) enabling real time waveform measurements of the current and voltages to be obtained. The system has been validated using measurements performed on a Heterojunction Bipolar Transistor operating in Class B with constant harmonic terminations on the load and source over variations in drive level.
{"title":"An automated active source and load pull measurement system","authors":"David, Williams, P. Tasker","doi":"10.1109/HFPSC.2001.962150","DOIUrl":"https://doi.org/10.1109/HFPSC.2001.962150","url":null,"abstract":"A fully automated electronic load and source pull measurement system has been developed using standard Agilent ESG Frequency sources. Combined with a vector corrected time-domain waveform measurement system based on the HP-MTA (Microwave Transition Analyser) enabling real time waveform measurements of the current and voltages to be obtained. The system has been validated using measurements performed on a Heterojunction Bipolar Transistor operating in Class B with constant harmonic terminations on the load and source over variations in drive level.","PeriodicalId":129428,"journal":{"name":"6th IEEE High Frequency Postgraduate Colloquium (Cat. No.01TH8574)","volume":"110 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117209736","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 : 2001-09-09DOI: 10.1109/HFPSC.2001.962156
A. Roullier-Callaghan
With the increased utilisation of mobile communications, and the speed necessary to keep radio systems efficient, a 'RAdioWave Coverage And Planning Tool', RAWCAPT, is proposed. This tool could prove not only cost efficient, but also time efficient for users needing to ascertain the optimal position for a transmitter-receiver radio systems for any urban terrain. The tool utilises a Lidar dataset as the input, due to fact that Lidar data is reasonably cheap compared to other forms of data. On completion of the tool, the full process of radio path planning will be contained within a solitary software application.
{"title":"A radio coverage and planning tool","authors":"A. Roullier-Callaghan","doi":"10.1109/HFPSC.2001.962156","DOIUrl":"https://doi.org/10.1109/HFPSC.2001.962156","url":null,"abstract":"With the increased utilisation of mobile communications, and the speed necessary to keep radio systems efficient, a 'RAdioWave Coverage And Planning Tool', RAWCAPT, is proposed. This tool could prove not only cost efficient, but also time efficient for users needing to ascertain the optimal position for a transmitter-receiver radio systems for any urban terrain. The tool utilises a Lidar dataset as the input, due to fact that Lidar data is reasonably cheap compared to other forms of data. On completion of the tool, the full process of radio path planning will be contained within a solitary software application.","PeriodicalId":129428,"journal":{"name":"6th IEEE High Frequency Postgraduate Colloquium (Cat. No.01TH8574)","volume":"2594 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128812870","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 : 2001-09-09DOI: 10.1109/HFPSC.2001.962182
M. Falah, D. Linton
The application of Non-Linear Transmission Line (NLTL) technology to the restoration of signal integrity in electro-optic back-planes technology is reported. The non-linear transmission line synthesized uses coplanar wave-guide because it has better performance than the micro-strip line.
{"title":"High data rate pulse regeneration using non-linear transmission line technology (NLTL)","authors":"M. Falah, D. Linton","doi":"10.1109/HFPSC.2001.962182","DOIUrl":"https://doi.org/10.1109/HFPSC.2001.962182","url":null,"abstract":"The application of Non-Linear Transmission Line (NLTL) technology to the restoration of signal integrity in electro-optic back-planes technology is reported. The non-linear transmission line synthesized uses coplanar wave-guide because it has better performance than the micro-strip line.","PeriodicalId":129428,"journal":{"name":"6th IEEE High Frequency Postgraduate Colloquium (Cat. No.01TH8574)","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129822709","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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