Pub Date : 2016-08-11DOI: 10.1109/MWSYM.2016.7540225
H. Saghlatoon, M. M. Honari, R. Mirzavand, P. Mousavi
In this paper, a miniaturized UHF RFID tag is developed for industrial harsh environment applications like oil and gas industries. The tag is designed based on an open-ended slot structure and fed by a primary radiator from the middle. Feeding the antenna using coupling mechanism by a primary radiator results to lower fabrication complexity and costs as well as mechanical durability against continuous vibrations, humidity, water and mud. The whole tag is 0.084λ×0.066λ and can be read up to 5 m in the US band and 3 m in the EU band. By utilization of low cost FR4 substrate alongside the magnetically coupled primary radiator the fabrication costs diminishes significantly. An open-ended slot fed from the middle with bent T-shape pattern for the closed-end and meandered pattern for the open-ended side acts as the antenna and matching circuit together. The measurement results prove the functionality of the designed tag.
{"title":"Low-cost miniaturized open-ended slot-based UHF RFID tag for harsh environment","authors":"H. Saghlatoon, M. M. Honari, R. Mirzavand, P. Mousavi","doi":"10.1109/MWSYM.2016.7540225","DOIUrl":"https://doi.org/10.1109/MWSYM.2016.7540225","url":null,"abstract":"In this paper, a miniaturized UHF RFID tag is developed for industrial harsh environment applications like oil and gas industries. The tag is designed based on an open-ended slot structure and fed by a primary radiator from the middle. Feeding the antenna using coupling mechanism by a primary radiator results to lower fabrication complexity and costs as well as mechanical durability against continuous vibrations, humidity, water and mud. The whole tag is 0.084λ×0.066λ and can be read up to 5 m in the US band and 3 m in the EU band. By utilization of low cost FR4 substrate alongside the magnetically coupled primary radiator the fabrication costs diminishes significantly. An open-ended slot fed from the middle with bent T-shape pattern for the closed-end and meandered pattern for the open-ended side acts as the antenna and matching circuit together. The measurement results prove the functionality of the designed tag.","PeriodicalId":6554,"journal":{"name":"2016 IEEE MTT-S International Microwave Symposium (IMS)","volume":"69 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2016-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86674960","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 : 2016-08-11DOI: 10.1109/MWSYM.2016.7540181
Alfredo Bautista, M. Aziz, F. Podevin, P. Ferrari
This paper presents a predictive model for Slow-wave Coplanar Striplines (S-CPS). A Quasi-TEM propagation mode has been assumed for developing the equivalent electrical model. Based on the geometries and definition of the back end of line, the model is capable of fully predict the behavior of the SCPS without any fitting parameters. The model was validated with measurements of S-CPS implemented in the 0.35-μm CMOS AMS technology. A good agreement is achieved between the model and measurements in a wide band (DC-40GHz). This model provides the designer a powerful tool for fast design of differential circuits, for which the use of S-CPS instead of microstrip lines can be very efficient.
{"title":"A predictive model for Slow-wave Coplanar Striplines in integrated technologies","authors":"Alfredo Bautista, M. Aziz, F. Podevin, P. Ferrari","doi":"10.1109/MWSYM.2016.7540181","DOIUrl":"https://doi.org/10.1109/MWSYM.2016.7540181","url":null,"abstract":"This paper presents a predictive model for Slow-wave Coplanar Striplines (S-CPS). A Quasi-TEM propagation mode has been assumed for developing the equivalent electrical model. Based on the geometries and definition of the back end of line, the model is capable of fully predict the behavior of the SCPS without any fitting parameters. The model was validated with measurements of S-CPS implemented in the 0.35-μm CMOS AMS technology. A good agreement is achieved between the model and measurements in a wide band (DC-40GHz). This model provides the designer a powerful tool for fast design of differential circuits, for which the use of S-CPS instead of microstrip lines can be very efficient.","PeriodicalId":6554,"journal":{"name":"2016 IEEE MTT-S International Microwave Symposium (IMS)","volume":"12 1","pages":"1-3"},"PeriodicalIF":0.0,"publicationDate":"2016-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83480894","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 : 2016-08-11DOI: 10.1109/MWSYM.2016.7540296
Ping Zhao, K. Qian, Ke-Li Wu
Full-duplex radios realize simultaneous bi-directional communications in the same frequency band. However, one of the bottlenecks is how to mediate the self-interference (SI) between the transmitter (Tx) and the receiver (Rx). In this paper, a novel passive microwave device called Coupled-resonator Decoupling Network (CRDN) is proposed. A prototype CRDN is built and tested for proof-of-concept, where the four-port device consists of two inter-coupled lines of coupled resonators. The SI is suppressed from -17 dB to below -41 dB within a frequency range of 50 MHz. This performance is superior to other RF front end SI cancellation schemes and demonstrates the potential applications of such device in a full-duplex wireless communication system.
{"title":"A Coupled-resonator Decoupling Network for full-duplex radios","authors":"Ping Zhao, K. Qian, Ke-Li Wu","doi":"10.1109/MWSYM.2016.7540296","DOIUrl":"https://doi.org/10.1109/MWSYM.2016.7540296","url":null,"abstract":"Full-duplex radios realize simultaneous bi-directional communications in the same frequency band. However, one of the bottlenecks is how to mediate the self-interference (SI) between the transmitter (Tx) and the receiver (Rx). In this paper, a novel passive microwave device called Coupled-resonator Decoupling Network (CRDN) is proposed. A prototype CRDN is built and tested for proof-of-concept, where the four-port device consists of two inter-coupled lines of coupled resonators. The SI is suppressed from -17 dB to below -41 dB within a frequency range of 50 MHz. This performance is superior to other RF front end SI cancellation schemes and demonstrates the potential applications of such device in a full-duplex wireless communication system.","PeriodicalId":6554,"journal":{"name":"2016 IEEE MTT-S International Microwave Symposium (IMS)","volume":"82 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2016-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79954430","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 : 2016-08-11DOI: 10.1109/MWSYM.2016.7540376
Alexander Tsatsoulas, Joseph Barkate, C. Baylis, R. Marks
The increased practice of dynamic spectrum allocation requires radar and communication systems that are able to change operating frequency and other performance criteria while maintaining performance metrics such as power efficiency and spectral compliance. This paper presents a simplex algorithm designed to allow frequency-agile circuits to quickly tune for maximum power-added efficiency. Simulation and measurement algorithm tests show that the algorithm produces consistent results from multiple starting points, and that the results show good agreement with traditional load-pull. This algorithm is expected to be useful in providing fast reconfiguration of transmitter power amplifiers.
{"title":"A simplex optimization technique for real-time, reconfigurable transmitter power amplifiers","authors":"Alexander Tsatsoulas, Joseph Barkate, C. Baylis, R. Marks","doi":"10.1109/MWSYM.2016.7540376","DOIUrl":"https://doi.org/10.1109/MWSYM.2016.7540376","url":null,"abstract":"The increased practice of dynamic spectrum allocation requires radar and communication systems that are able to change operating frequency and other performance criteria while maintaining performance metrics such as power efficiency and spectral compliance. This paper presents a simplex algorithm designed to allow frequency-agile circuits to quickly tune for maximum power-added efficiency. Simulation and measurement algorithm tests show that the algorithm produces consistent results from multiple starting points, and that the results show good agreement with traditional load-pull. This algorithm is expected to be useful in providing fast reconfiguration of transmitter power amplifiers.","PeriodicalId":6554,"journal":{"name":"2016 IEEE MTT-S International Microwave Symposium (IMS)","volume":"115 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2016-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77915763","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 : 2016-08-11DOI: 10.1109/MWSYM.2016.7540438
R. Snyder, S. Reising
This session is dedicated to the career and memory of Dr. Kiyo Tomiyasu. It is a celebration of his life! Kiyo passed away on December 9, 2015, at the age of 96. During his long and active career, Kiyo contributed to the development of ferrites, microwave components, spectroscopy instruments, lasers, radiometers, and perhaps even more importantly, to the IEEE careers of many of us. From 1955 to 2013, Kiyo was an active volunteer in MTT-S and GRSS as well as serving on multiple IEEE boards. His many contributions include the creation of IEEE Foundation funds that support students as well as the IEEE Kiyo Tomiyasu Award, an IEEE technical field award to honor early- to mid-career contributions.
{"title":"Memorial session in honor of Dr. Kiyo Tomiyasu","authors":"R. Snyder, S. Reising","doi":"10.1109/MWSYM.2016.7540438","DOIUrl":"https://doi.org/10.1109/MWSYM.2016.7540438","url":null,"abstract":"This session is dedicated to the career and memory of Dr. Kiyo Tomiyasu. It is a celebration of his life! Kiyo passed away on December 9, 2015, at the age of 96. During his long and active career, Kiyo contributed to the development of ferrites, microwave components, spectroscopy instruments, lasers, radiometers, and perhaps even more importantly, to the IEEE careers of many of us. From 1955 to 2013, Kiyo was an active volunteer in MTT-S and GRSS as well as serving on multiple IEEE boards. His many contributions include the creation of IEEE Foundation funds that support students as well as the IEEE Kiyo Tomiyasu Award, an IEEE technical field award to honor early- to mid-career contributions.","PeriodicalId":6554,"journal":{"name":"2016 IEEE MTT-S International Microwave Symposium (IMS)","volume":"355 1","pages":"1-1"},"PeriodicalIF":0.0,"publicationDate":"2016-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89292641","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 : 2016-08-11DOI: 10.1109/MWSYM.2016.7540427
Tengda Mei, Yuehang Xu, Oupeng Li, Yu Lan, Yunqiu Wu, R. Xu, Yuanfu Chen, Yanrong Li
This paper presents a compact small signal equivalent circuit model of graphene resonant channel transistors (G-RCTs) suitable for different bias conditions. The model combines a bias dependent model for a GFET with a continuum mechanics model for 2-D graphene membrane. The model has been validated by graphene resonators fabricated by mechanical exfoliation techniques and transfer techniques. The characterization of G-RCT at very wide gate bias range with Vgs from -20 to 20V is predicted for the first time by using equivalent circuit model, which proves the validation of the proposed model. With the proposed compact model, the RCTs can be useful for developing high sensitivity sensor, or in the perspective of high quality RF filters by using graphene nano-electromechanical systems (NEMS).
{"title":"Accurate multi-bias equivalent circuit model for graphene resonant channel transistors","authors":"Tengda Mei, Yuehang Xu, Oupeng Li, Yu Lan, Yunqiu Wu, R. Xu, Yuanfu Chen, Yanrong Li","doi":"10.1109/MWSYM.2016.7540427","DOIUrl":"https://doi.org/10.1109/MWSYM.2016.7540427","url":null,"abstract":"This paper presents a compact small signal equivalent circuit model of graphene resonant channel transistors (G-RCTs) suitable for different bias conditions. The model combines a bias dependent model for a GFET with a continuum mechanics model for 2-D graphene membrane. The model has been validated by graphene resonators fabricated by mechanical exfoliation techniques and transfer techniques. The characterization of G-RCT at very wide gate bias range with Vgs from -20 to 20V is predicted for the first time by using equivalent circuit model, which proves the validation of the proposed model. With the proposed compact model, the RCTs can be useful for developing high sensitivity sensor, or in the perspective of high quality RF filters by using graphene nano-electromechanical systems (NEMS).","PeriodicalId":6554,"journal":{"name":"2016 IEEE MTT-S International Microwave Symposium (IMS)","volume":"2 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2016-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86704452","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 : 2016-08-11DOI: 10.1109/MWSYM.2016.7540422
F. Thome, M. Ohlrogge, A. Leuther, M. Schlechtweg, O. Ambacher
This paper reports on a design study for millimeter wave single-pole multiple-throw switches, which are based on shunt transistors. For the investigation of an optimized design flow this study focuses on the three main steps of a millimeter wave switch design: identifying the optimum transistor gate width, large signal modeling of shunt transistors and the MMIC design. Based on the investigations of the optimum transistor gate width, it will be shown that insertion loss and output signal dynamic of a switch are directly correlated to the on-resistance of the utilized semiconductor technology. To prove the feasibility of this study, two RF SPDT switch MMICs, operating in the frequency range from 53 to 150 GHz and from 200 to 330 GHz, respectively, were designed and fabricated. Both switches show low insertion loss, high output signal dynamic, high yield and good agreement to the S-parameter simulations, based on the proposed shunt FET model. The proposed W-band and H-band SPDT switch MMICs achieve an insertion loss of 2 dB and 1.7 dB, respectively, and an output signal dynamic of up to 47 and 20 dB, respectively.
{"title":"An investigation of millimeter wave switches based on shunt transistors including SPDT SWITCH MMICs up to 300 GHz","authors":"F. Thome, M. Ohlrogge, A. Leuther, M. Schlechtweg, O. Ambacher","doi":"10.1109/MWSYM.2016.7540422","DOIUrl":"https://doi.org/10.1109/MWSYM.2016.7540422","url":null,"abstract":"This paper reports on a design study for millimeter wave single-pole multiple-throw switches, which are based on shunt transistors. For the investigation of an optimized design flow this study focuses on the three main steps of a millimeter wave switch design: identifying the optimum transistor gate width, large signal modeling of shunt transistors and the MMIC design. Based on the investigations of the optimum transistor gate width, it will be shown that insertion loss and output signal dynamic of a switch are directly correlated to the on-resistance of the utilized semiconductor technology. To prove the feasibility of this study, two RF SPDT switch MMICs, operating in the frequency range from 53 to 150 GHz and from 200 to 330 GHz, respectively, were designed and fabricated. Both switches show low insertion loss, high output signal dynamic, high yield and good agreement to the S-parameter simulations, based on the proposed shunt FET model. The proposed W-band and H-band SPDT switch MMICs achieve an insertion loss of 2 dB and 1.7 dB, respectively, and an output signal dynamic of up to 47 and 20 dB, respectively.","PeriodicalId":6554,"journal":{"name":"2016 IEEE MTT-S International Microwave Symposium (IMS)","volume":"4 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2016-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75346051","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 : 2016-08-11DOI: 10.1109/MWSYM.2016.7540395
O. Tornblad, L. Giffin, C. Blair
Substrate network modeling of RF Power LDMOS devices is important for accurate modeling at higher frequencies. Substrate losses can account for a considerable amount of the losses in the device and directly affects the efficiency, which is one of the most critical performance criteria of a power amplifier. In this paper, an improved substrate network model for RF Power LDMOS devices is presented that can more accurately predict these losses and be of help in designing improved device structures. Nonlinear resistors representing a depleting drain to body junction as a function of drain to source bias are included in a physical way. It is shown that the model gives good agreement with s-parameters for varying LDD lengths and as a function of drain to source bias.
{"title":"Substrate network modeling of RF Power LDMOS devices including nonlinear effects","authors":"O. Tornblad, L. Giffin, C. Blair","doi":"10.1109/MWSYM.2016.7540395","DOIUrl":"https://doi.org/10.1109/MWSYM.2016.7540395","url":null,"abstract":"Substrate network modeling of RF Power LDMOS devices is important for accurate modeling at higher frequencies. Substrate losses can account for a considerable amount of the losses in the device and directly affects the efficiency, which is one of the most critical performance criteria of a power amplifier. In this paper, an improved substrate network model for RF Power LDMOS devices is presented that can more accurately predict these losses and be of help in designing improved device structures. Nonlinear resistors representing a depleting drain to body junction as a function of drain to source bias are included in a physical way. It is shown that the model gives good agreement with s-parameters for varying LDD lengths and as a function of drain to source bias.","PeriodicalId":6554,"journal":{"name":"2016 IEEE MTT-S International Microwave Symposium (IMS)","volume":"53 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2016-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91223670","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 : 2016-08-11DOI: 10.1109/MWSYM.2016.7540311
Jun Gi Hong, Seok-Jae Lee, Jongsik Lim, Won‐Sang Yoon, Sang‐Min Han
A channel-selective super regenerative receiver (SRR) system is proposed with improved channel selectivity. The proposed SRR system operates only at a valid incoming signal due to the RF spectrum sensing functionality. To overcome the rough channel selectivity of the SRR, a systemic methodology is proposed for controlling quenching signal waveforms. From the experimental evaluations, the proposed system presented excellent channel selection capability of the 3.5-MHz channel bandwidth. The proposed architecture can allocate at least three times the number of channels for cognitive IoT sensor networks as that of previous ones.
{"title":"RF spectrum sensing receiver system with improved frequency channel selectivity for cognitive iot sensor network applications","authors":"Jun Gi Hong, Seok-Jae Lee, Jongsik Lim, Won‐Sang Yoon, Sang‐Min Han","doi":"10.1109/MWSYM.2016.7540311","DOIUrl":"https://doi.org/10.1109/MWSYM.2016.7540311","url":null,"abstract":"A channel-selective super regenerative receiver (SRR) system is proposed with improved channel selectivity. The proposed SRR system operates only at a valid incoming signal due to the RF spectrum sensing functionality. To overcome the rough channel selectivity of the SRR, a systemic methodology is proposed for controlling quenching signal waveforms. From the experimental evaluations, the proposed system presented excellent channel selection capability of the 3.5-MHz channel bandwidth. The proposed architecture can allocate at least three times the number of channels for cognitive IoT sensor networks as that of previous ones.","PeriodicalId":6554,"journal":{"name":"2016 IEEE MTT-S International Microwave Symposium (IMS)","volume":"22 1","pages":"1-3"},"PeriodicalIF":0.0,"publicationDate":"2016-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86274751","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 : 2016-08-11DOI: 10.1109/MWSYM.2016.7540157
Shih-Fong Chao, Kun-Rong Lin, Yen-Yu Chen
In this paper, a filtering reconfigurable power divider is proposed based on novel switched-filter matching network (SFMN). The reconfigurable impedance matching can be obtained by applying different bias conditions to the p-i-n diodes loaded at the resonators and the feed lines. The circuit has one two-way divider mode and two one-way transmission modes. In the two-way divider mode, a second-order bandpass response is measured at 0.98 GHz with insertion loss of 1.7 dB. In the one-way transmission mode, the circuit has a measured insertion of 0.57 dB and an isolation of 50 dB.
{"title":"A reconfigurable filtering power divider","authors":"Shih-Fong Chao, Kun-Rong Lin, Yen-Yu Chen","doi":"10.1109/MWSYM.2016.7540157","DOIUrl":"https://doi.org/10.1109/MWSYM.2016.7540157","url":null,"abstract":"In this paper, a filtering reconfigurable power divider is proposed based on novel switched-filter matching network (SFMN). The reconfigurable impedance matching can be obtained by applying different bias conditions to the p-i-n diodes loaded at the resonators and the feed lines. The circuit has one two-way divider mode and two one-way transmission modes. In the two-way divider mode, a second-order bandpass response is measured at 0.98 GHz with insertion loss of 1.7 dB. In the one-way transmission mode, the circuit has a measured insertion of 0.57 dB and an isolation of 50 dB.","PeriodicalId":6554,"journal":{"name":"2016 IEEE MTT-S International Microwave Symposium (IMS)","volume":"67 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2016-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88410590","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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