Pub Date : 2025-07-03DOI: 10.1109/TTHZ.2025.3585672
Tomofumi Ikari;Yoshiaki Sasaki;Chiko Otani
We have developed a body scanner that can measure both the front and back sides of a pedestrian walking at 4 km/h using a single 300 GHz frequency-modulated continuous-wave (FMCW) radar and scanning optical system. While maintaining a simple system architecture, the design builds upon a previously proposed method, with a novel implementation of a second beam to enable acquisition of the pedestrian's back side in a single pass. We have evaluated the position dependence of the lateral resolution and telecentricity, satisfying the requirements for both sides. We have also introduced the new method so as to perform three-dimensional rendering of both sides in a short time using their intensity images. Furthermore, we have newly evaluated the sweep time dependence of the noise level of the range profile, by changing the frequency sweep time of the signal source of the FMCW radar, digital direct synthesizer, from 10 μs to 10 ms.
{"title":"Development of a Two-Beam Terahertz FMCW Walk-Through Body Scanner for Seamless Security Screening","authors":"Tomofumi Ikari;Yoshiaki Sasaki;Chiko Otani","doi":"10.1109/TTHZ.2025.3585672","DOIUrl":"https://doi.org/10.1109/TTHZ.2025.3585672","url":null,"abstract":"We have developed a body scanner that can measure both the front and back sides of a pedestrian walking at 4 km/h using a single 300 GHz frequency-modulated continuous-wave (FMCW) radar and scanning optical system. While maintaining a simple system architecture, the design builds upon a previously proposed method, with a novel implementation of a second beam to enable acquisition of the pedestrian's back side in a single pass. We have evaluated the position dependence of the lateral resolution and telecentricity, satisfying the requirements for both sides. We have also introduced the new method so as to perform three-dimensional rendering of both sides in a short time using their intensity images. Furthermore, we have newly evaluated the sweep time dependence of the noise level of the range profile, by changing the frequency sweep time of the signal source of the FMCW radar, digital direct synthesizer, from 10 μs to 10 ms.","PeriodicalId":13258,"journal":{"name":"IEEE Transactions on Terahertz Science and Technology","volume":"15 5","pages":"771-780"},"PeriodicalIF":3.9,"publicationDate":"2025-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11068180","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144997974","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-07-03DOI: 10.1109/TTHZ.2025.3582135
{"title":"TechRxiv: Share Your Preprint Research with the World!","authors":"","doi":"10.1109/TTHZ.2025.3582135","DOIUrl":"https://doi.org/10.1109/TTHZ.2025.3582135","url":null,"abstract":"","PeriodicalId":13258,"journal":{"name":"IEEE Transactions on Terahertz Science and Technology","volume":"15 4","pages":"740-740"},"PeriodicalIF":3.9,"publicationDate":"2025-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11068938","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144550684","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-07-03DOI: 10.1109/TTHZ.2025.3582008
{"title":"IEEE Transactions on Terahertz Science and Technology Publication Information","authors":"","doi":"10.1109/TTHZ.2025.3582008","DOIUrl":"https://doi.org/10.1109/TTHZ.2025.3582008","url":null,"abstract":"","PeriodicalId":13258,"journal":{"name":"IEEE Transactions on Terahertz Science and Technology","volume":"15 4","pages":"C3-C3"},"PeriodicalIF":3.9,"publicationDate":"2025-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11068939","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144550716","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-07-03DOI: 10.1109/TTHZ.2025.3585674
Atif Jameel;Zhanliang Wang;Jibran Latif;Muhammad Khawar Nadeem;Syed Aziz Shah;Bilawal Ali;Yubin Gong
This article presents the analytical design, simulation, and cold-test validation of a radial slow-wave structure for terahertz applications, addressing the limitations of conventional axial designs. Radial vacuum electron devices enhance the interaction area, reduce space charge effects, and enable compact, magnetic field-free operation, making them well-suited for high-power THz sources. A mathematical framework is developed to derive dispersion equations for the radial configuration, and numerical simulations to analyze the dispersion characteristics, external quality factor, and interaction impedance. A radial backward wave oscillator (BWO) is designed to validate the analytical model at 0.65 THz. Its performance is evaluated through particle-in-cell simulations, which model the interaction between the diverging radial sheet electron beam and the electromagnetic wave. The particle simulation confirms that the radial BWO operates without an external magnetic field, achieving a peak output power of 46.4 W at 0.651 THz using a 20.2-kV, 400-mA electron beam. A matched TEM-TE$_{10}$ mode converter is designed to extract the RF power efficiently for practical applications. The proposed BWO, comprising 40 periods and an integrated mode converter, is fabricated with precise surface finishing, dimensional accuracy, and compatibility with THz operational requirements. The cold test of the BWO with the mode converter shows an S$_{11}$ parameter of approximately −13 dB at the desired frequencies, closely matching the simulated results. These findings highlight the potential of radial BWO as compact, high-power THz sources, enabling stable and efficient operation for advanced applications.
{"title":"Analytical Modeling, Simulation, and Cold Testing of a Radial SWS for THz Applications","authors":"Atif Jameel;Zhanliang Wang;Jibran Latif;Muhammad Khawar Nadeem;Syed Aziz Shah;Bilawal Ali;Yubin Gong","doi":"10.1109/TTHZ.2025.3585674","DOIUrl":"https://doi.org/10.1109/TTHZ.2025.3585674","url":null,"abstract":"This article presents the analytical design, simulation, and cold-test validation of a radial slow-wave structure for terahertz applications, addressing the limitations of conventional axial designs. Radial vacuum electron devices enhance the interaction area, reduce space charge effects, and enable compact, magnetic field-free operation, making them well-suited for high-power THz sources. A mathematical framework is developed to derive dispersion equations for the radial configuration, and numerical simulations to analyze the dispersion characteristics, external quality factor, and interaction impedance. A radial backward wave oscillator (BWO) is designed to validate the analytical model at 0.65 THz. Its performance is evaluated through particle-in-cell simulations, which model the interaction between the diverging radial sheet electron beam and the electromagnetic wave. The particle simulation confirms that the radial BWO operates without an external magnetic field, achieving a peak output power of 46.4 W at 0.651 THz using a 20.2-kV, 400-mA electron beam. A matched TEM-TE<inline-formula><tex-math>$_{10}$</tex-math></inline-formula> mode converter is designed to extract the RF power efficiently for practical applications. The proposed BWO, comprising 40 periods and an integrated mode converter, is fabricated with precise surface finishing, dimensional accuracy, and compatibility with THz operational requirements. The cold test of the BWO with the mode converter shows an S<inline-formula><tex-math>$_{11}$</tex-math></inline-formula> parameter of approximately −13 dB at the desired frequencies, closely matching the simulated results. These findings highlight the potential of radial BWO as compact, high-power THz sources, enabling stable and efficient operation for advanced applications.","PeriodicalId":13258,"journal":{"name":"IEEE Transactions on Terahertz Science and Technology","volume":"15 5","pages":"903-913"},"PeriodicalIF":3.9,"publicationDate":"2025-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144998301","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-07-03DOI: 10.1109/TTHZ.2025.3582004
{"title":"IEEE Microwave Theory and Techniques Society Information","authors":"","doi":"10.1109/TTHZ.2025.3582004","DOIUrl":"https://doi.org/10.1109/TTHZ.2025.3582004","url":null,"abstract":"","PeriodicalId":13258,"journal":{"name":"IEEE Transactions on Terahertz Science and Technology","volume":"15 4","pages":"C2-C2"},"PeriodicalIF":3.9,"publicationDate":"2025-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11068958","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144550262","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-07-03DOI: 10.1109/TTHZ.2025.3582006
{"title":"IEEE Transactions on Terahertz Science and Technology Information for Authors","authors":"","doi":"10.1109/TTHZ.2025.3582006","DOIUrl":"https://doi.org/10.1109/TTHZ.2025.3582006","url":null,"abstract":"","PeriodicalId":13258,"journal":{"name":"IEEE Transactions on Terahertz Science and Technology","volume":"15 4","pages":"738-739"},"PeriodicalIF":3.9,"publicationDate":"2025-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11068940","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144550261","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-06-27DOI: 10.1109/TTHZ.2025.3583912
Daniel Headland;Guillermo Carpintero
We address critical physical fragility issues associated with terahertz integrated all-silicon substrateless devices. This is necessary because, although the current state-of-the-art offers excellent electromagnetic performance, real-world deployment is currently held back by structural weaknesses. One such example is the input coupler, which has previously taken the form of an exposed taper that reduces core dimensions over several wavelengths, and is vulnerable to breakage. This is replaced with a compact subwavelength slot-waveguide coupler, which exploits reflection-cancellation as opposed to a progressive transition. The other key structural weakness is the in-plane integrated support that physically suspends the substrateless waveguide's core, and this is addressed with multimode effects that localize a field null to the point of contact with a solid supporting beam. The resultant robust waveguide platform exhibits a working relative bandwidth of $sim$31%, which is sufficient for terahertz communications in standard allocated bands. Multimode effects are also exploited to realize an integrated photonic 2 × 2 splitter, which is incidentally the first demonstration of an integrated dielectric multimode interferometer splitter in the terahertz range.
{"title":"Robust Unclad Terahertz Waveguides and Integrated Components Enabled by Multimode Effects and Matched Slot Couplers","authors":"Daniel Headland;Guillermo Carpintero","doi":"10.1109/TTHZ.2025.3583912","DOIUrl":"https://doi.org/10.1109/TTHZ.2025.3583912","url":null,"abstract":"We address critical physical fragility issues associated with terahertz integrated all-silicon substrateless devices. This is necessary because, although the current state-of-the-art offers excellent electromagnetic performance, real-world deployment is currently held back by structural weaknesses. One such example is the input coupler, which has previously taken the form of an exposed taper that reduces core dimensions over several wavelengths, and is vulnerable to breakage. This is replaced with a compact subwavelength slot-waveguide coupler, which exploits reflection-cancellation as opposed to a progressive transition. The other key structural weakness is the in-plane integrated support that physically suspends the substrateless waveguide's core, and this is addressed with multimode effects that localize a field null to the point of contact with a solid supporting beam. The resultant robust waveguide platform exhibits a working relative bandwidth of <inline-formula><tex-math>$sim$</tex-math></inline-formula>31%, which is sufficient for terahertz communications in standard allocated bands. Multimode effects are also exploited to realize an integrated photonic 2 × 2 splitter, which is incidentally the first demonstration of an integrated dielectric multimode interferometer splitter in the terahertz range.","PeriodicalId":13258,"journal":{"name":"IEEE Transactions on Terahertz Science and Technology","volume":"15 5","pages":"885-893"},"PeriodicalIF":3.9,"publicationDate":"2025-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11054290","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144998204","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-06-16DOI: 10.1109/TTHZ.2025.3580257
Ehsan Hafezi;Kamal Sarabandi
This article presents a device capable of generating different or hybrid orbital angular momentum (OAM) modes at 225 GHz using a mechanically tunable configuration. The device is composed of two 10 cm-diameter reflectionless plates, each 0.6 mm thick, designed to work together such that their combined phase response produces specific OAM modes, once properly aligned. These plates are patterned with metallic traces on thin glass substrates to form a miniaturized-element frequency selective surface structure. These traces are microfabricated with high precision to achieve accurate transmission phase modulation across the wafer. The mechanism enabling mode flexibility relies on discretizing the plates into finite number of angular sectors, each with a unique phase response. When the plates are properly aligned, the combined phase from corresponding sectors can generate a desired OAM mode. By rotating one plate relative to the other, new alignments between sectors produce different combined phase profiles, allowing for the generation of a different mode. The reflectionless nature of the plates ensures that the overall performance is largely insensitive to the distance between the two plates. Transmission phase measurements of individual and combined plates are validated via near-field measurement and the resulting phase profiles confirmed the generation of distinct OAM modes in agreement with simulation predictions. This device demonstrates an innovative approach to OAM mode generation, with potential applications in near-field communication and high-resolution radar imaging systems.
{"title":"Reconfigurable Orbital Angular Momentum Mode Generation at 225 GHz Using Cascaded Reflectionless Miniaturized-Element Frequency Selective Surface Phase Plates","authors":"Ehsan Hafezi;Kamal Sarabandi","doi":"10.1109/TTHZ.2025.3580257","DOIUrl":"https://doi.org/10.1109/TTHZ.2025.3580257","url":null,"abstract":"This article presents a device capable of generating different or hybrid orbital angular momentum (OAM) modes at 225 GHz using a mechanically tunable configuration. The device is composed of two 10 cm-diameter reflectionless plates, each 0.6 mm thick, designed to work together such that their combined phase response produces specific OAM modes, once properly aligned. These plates are patterned with metallic traces on thin glass substrates to form a miniaturized-element frequency selective surface structure. These traces are microfabricated with high precision to achieve accurate transmission phase modulation across the wafer. The mechanism enabling mode flexibility relies on discretizing the plates into finite number of angular sectors, each with a unique phase response. When the plates are properly aligned, the combined phase from corresponding sectors can generate a desired OAM mode. By rotating one plate relative to the other, new alignments between sectors produce different combined phase profiles, allowing for the generation of a different mode. The reflectionless nature of the plates ensures that the overall performance is largely insensitive to the distance between the two plates. Transmission phase measurements of individual and combined plates are validated via near-field measurement and the resulting phase profiles confirmed the generation of distinct OAM modes in agreement with simulation predictions. This device demonstrates an innovative approach to OAM mode generation, with potential applications in near-field communication and high-resolution radar imaging systems.","PeriodicalId":13258,"journal":{"name":"IEEE Transactions on Terahertz Science and Technology","volume":"15 5","pages":"821-830"},"PeriodicalIF":3.9,"publicationDate":"2025-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144998268","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-06-12DOI: 10.1109/TTHZ.2025.3579299
Pouyan Rezapoor;Aleksi Tamminen;Juha Ala-Laurinaho;Dan Ruan;Zachary Taylor
Terahertz (THz) imaging has emerged as a promising technology in medical diagnostics, thanks to nonionizing radiation and the high sensitivity of THz waves to water content. However, in vivo, THz imaging system designs face challenges, such as slow mechanical scanning, limited field-of-view, and variable incidence angle due to poor telecentricity. To address these limitations, we present the telecentric offset reflective imaging system, a novel dual-mirror scanning design optimized for high-speed, distortion-free imaging. Utilizing a telecentric $f-theta$ lens and ray-tracing and physical optics simulations, the system achieves uniform resolution across a 50 × 50 mm$^{2}$ field of view. System capability is demonstrated through broadband spectral imaging of a USAF resolution test target across WR-2.2 (325–500 GHz) and WR-1.5 (500–700 GHz) rectangular waveguide frequency bands, achieving consistent beam focus and minimal distortion, with maximum deviation of 2.7$^{circ }$ from normal incidence and beam waist of 2.1 $lambda$ at the edge of the field of view. Hydration sensitivity is validated by imaging wet tissue paper, illustrating its sensitivity to temporal changes in water content. Further, in vivo, imaging of human skin after capsaicin patch application reveals localized hydration variations influenced by biochemical responses and adhesive patch removal.
{"title":"A Telecentric Offset Reflective Imaging System (TORIS) for Terahertz Imaging and Spectroscopy","authors":"Pouyan Rezapoor;Aleksi Tamminen;Juha Ala-Laurinaho;Dan Ruan;Zachary Taylor","doi":"10.1109/TTHZ.2025.3579299","DOIUrl":"https://doi.org/10.1109/TTHZ.2025.3579299","url":null,"abstract":"Terahertz (THz) imaging has emerged as a promising technology in medical diagnostics, thanks to nonionizing radiation and the high sensitivity of THz waves to water content. However, in vivo, THz imaging system designs face challenges, such as slow mechanical scanning, limited field-of-view, and variable incidence angle due to poor telecentricity. To address these limitations, we present the telecentric offset reflective imaging system, a novel dual-mirror scanning design optimized for high-speed, distortion-free imaging. Utilizing a telecentric <inline-formula><tex-math>$f-theta$</tex-math></inline-formula> lens and ray-tracing and physical optics simulations, the system achieves uniform resolution across a 50 × 50 mm<inline-formula><tex-math>$^{2}$</tex-math></inline-formula> field of view. System capability is demonstrated through broadband spectral imaging of a USAF resolution test target across WR-2.2 (325–500 GHz) and WR-1.5 (500–700 GHz) rectangular waveguide frequency bands, achieving consistent beam focus and minimal distortion, with maximum deviation of 2.7<inline-formula><tex-math>$^{circ }$</tex-math></inline-formula> from normal incidence and beam waist of 2.1 <inline-formula><tex-math>$lambda$</tex-math></inline-formula> at the edge of the field of view. Hydration sensitivity is validated by imaging wet tissue paper, illustrating its sensitivity to temporal changes in water content. Further, in vivo, imaging of human skin after capsaicin patch application reveals localized hydration variations influenced by biochemical responses and adhesive patch removal.","PeriodicalId":13258,"journal":{"name":"IEEE Transactions on Terahertz Science and Technology","volume":"15 5","pages":"787-799"},"PeriodicalIF":3.9,"publicationDate":"2025-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11031208","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145011334","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-06-12DOI: 10.1109/TTHZ.2025.3579298
Philip Dindo;Alessandro Navarrini;Joseph G. Lambert;Anthony R. Kerr;Shing-Kuo Pan;Marian Pospieszalski;Claudio Jarufe;John E. Effland;Kamaljeet Saini
A new method is presented for measuring the intermediate frequency (IF) output impedance (ZIF) of a superconducting tunnel junction (SIS) mixer at cryogenic temperatures. As an example, the impedance ZIF of an atacama large millimeter/submillimeter array band 6 (211–275 GHz) SIS mixer chip was measured at the IF bonding pad. The setup uses a commercial vector network analyzer (VNA) with sensitivity enhancements to increase the dynamic range and allow low-power-one-port reflection coefficient (Γ if) measurements. A coupler inside the VNA is bypassed and replaced with an equivalent cold coupler inside the cryostat. The bias to the mixer is provided through the IF isolator. A cryogenic low-noise amplifier in the return path to the VNA increases its dynamic range. One-port calibration standards (short, open, and 50 Ω) are used, and the impedance is de-embedded from the calibration reference plane to the IF bonding pad of the mixer chip using the proprietary automatic fixture removal capability of the Keysight Technologies VNA. This approach allows direct measurement of the amplitude and phase of ΓIF and hence ZIF, from 2 to 16 GHz with very low power levels at the device under test. The measured results are compared with the predictions made from combining Tucker's quantum mixer theory with electromagnetic model of the mixer.
{"title":"VNA Measurement of the IF Output Impedance of an SIS Mixer","authors":"Philip Dindo;Alessandro Navarrini;Joseph G. Lambert;Anthony R. Kerr;Shing-Kuo Pan;Marian Pospieszalski;Claudio Jarufe;John E. Effland;Kamaljeet Saini","doi":"10.1109/TTHZ.2025.3579298","DOIUrl":"https://doi.org/10.1109/TTHZ.2025.3579298","url":null,"abstract":"A new method is presented for measuring the intermediate frequency (IF) output impedance (Z<sub>IF</sub>) of a superconducting tunnel junction (SIS) mixer at cryogenic temperatures. As an example, the impedance Z<sub>IF</sub> of an atacama large millimeter/submillimeter array band 6 (211–275 GHz) SIS mixer chip was measured at the IF bonding pad. The setup uses a commercial vector network analyzer (VNA) with sensitivity enhancements to increase the dynamic range and allow low-power-one-port reflection coefficient (Γ<sub> <small>if</small></sub>) measurements. A coupler inside the VNA is bypassed and replaced with an equivalent cold coupler inside the cryostat. The bias to the mixer is provided through the IF isolator. A cryogenic low-noise amplifier in the return path to the VNA increases its dynamic range. One-port calibration standards (short, open, and 50 Ω) are used, and the impedance is de-embedded from the calibration reference plane to the IF bonding pad of the mixer chip using the proprietary automatic fixture removal capability of the Keysight Technologies VNA. This approach allows direct measurement of the amplitude and phase of Γ<sub>IF</sub> and hence Z<sub>IF</sub>, from 2 to 16 GHz with very low power levels at the device under test. The measured results are compared with the predictions made from combining Tucker's quantum mixer theory with electromagnetic model of the mixer.","PeriodicalId":13258,"journal":{"name":"IEEE Transactions on Terahertz Science and Technology","volume":"15 5","pages":"894-902"},"PeriodicalIF":3.9,"publicationDate":"2025-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144998183","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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