| 1. |
- Ankel, Martin, 1996, et al.
(författare)
-
Bistatic noise radar: Demonstration of correlation noise suppression
- 2023
-
Ingår i: IET Radar, Sonar and Navigation. - : Institution of Engineering and Technology (IET). - 1751-8792 .- 1751-8784. ; 17:3, s. 351-361
-
Tidskriftsartikel (refereegranskat)abstract
- In this study, spatial separation of the radar transmitter and receiver units is considered, as a means of reducing the masking effect in noise radars. A bistatic radar system is constructed, with emphasis on a lightweight transmitter unit that can be mounted on a commercial Unmanned Aerial Vehicle (UAV). The system uses pseudo-random noise, generated digitally at the receiver and transmitter units. Correlation losses, due to non-linearities in the transmitter and receiver units, are measured to 0.1 dB. This study shows that by separating the transmitter and receiver unit the masking effect is significantly reduced, compared to a monostatic setup. This reduction is enough for the system to detect a slow flying UAV. Thus, bistatic separation should be considered as a practical tool to reduce the masking effect. By processing clutter with an extended CLEAN algorithm, the correlation noise floor is further suppressed.
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| 2. |
- Ankel, Martin, 1996, et al.
(författare)
-
Experimental Evaluation of Moving Target Compensation in High Time-Bandwidth Noise Radar
- 2023
-
Ingår i: 20th European Radar Conference, EuRAD 2023. ; , s. 213-216
-
Konferensbidrag (refereegranskat)abstract
- In this article, the effect a moving target has on the signal-to-interference-plus-noise-ratio (SINR) for high time-bandwidth noise radars is investigated. To compensate for cell migration we apply a computationally efficient stretch processing algorithm that is tailored for batched processing and suitable for implementation onto a real-time radar processor. The performance of the algorithm is studied using experimental data. In the experiment, pseudorandom noise, with a bandwidth of 100 MHz, is generated and transmitted in real-time. An unmanned aerial vehicle (UAV), flown at a speed of 11.5 m/s, is acting as a target. For an integration time of 1 s, the algorithm is shown to yield an increase in SINR of roughly 13 dB, compared to no compensation. It is also shown that coherent integration times of 2.5 s can be achieved.
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| 3. |
- Ankel, Martin, et al.
(författare)
-
Experimental Evaluation of Moving Target Compensation in High Time-Bandwidth Noise Radar
- 2023
-
Ingår i: Proceedings 20th European Radar Conference (EuRAD). - : Institute of Electrical and Electronics Engineers (IEEE). ; , s. 213-216
-
Konferensbidrag (refereegranskat)abstract
- In this article, the effect a moving target has on the signal-to-interference-plus-noise-ratio (SINR) for high time-bandwidth noise radars is investigated. To compensate for cell migration we apply a computationally efficient stretch processing algorithm that is tailored for batched processing and suitable for implementation onto a real-time radar processor. The performance of the algorithm is studied using experimental data. In the experiment, pseudorandom noise, with a bandwidth of 100 MHz, is generated and transmitted in real-time. An unmanned aerial vehicle (UAV), flown at a speed of 11.5 m/s, is acting as a target. For an integration time of 1 s, the algorithm is shown to yield an increase in SINR of roughly 13 dB, compared to no compensation. It is also shown that coherent integration times of 2.5 s can be achieved.
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| 4. |
- Ankel, Martin, 1996, et al.
(författare)
-
Implementation of a coherent real‐time noise radar system
- 2023
-
Ingår i: IET radar, sonar & navigation. - : Institution of Engineering and Technology (IET). - 1751-8784 .- 1751-8792.
-
Tidskriftsartikel (refereegranskat)abstract
- The utilisation of continuous random waveforms for radar, that is, noise radar, has been extensively studied as a candidate for low probability of intercept operation. However, compared with the more traditional pulse-Doppler radar, noise radar systems are significantly more complicated to implement, which is likely why few systems exist. If noise radar systems are to see the light of day, system design, implementation, limitations etc., must be investigated. Therefore, the authors examine and detail the implementation of a real-time noise radar system on a field programmable gate array. The system is capable of operating with 100% duty cycle, 200 MHz bandwidth, and 268 ms integration time while processing a range of about 8.5 km. Additionally, the system can perform real-time moving target compensation to reduce cell migration. System performance is primarily limited by the memory bandwidth of the off-chip dynamic random access memory.
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| 5. |
- Bonmann, Marlene, 1988, et al.
(författare)
-
Sub-millimetre wave range-Doppler radar as a diagnostic tool for gas-solids systems - solids concentration measurements
- 2023
-
Ingår i: Advanced Powder Technology. - : Elsevier BV. - 0921-8831 .- 1568-5527. ; 34:1
-
Tidskriftsartikel (refereegranskat)abstract
- Current non-intrusive measurement techniques for characterising the solids flow in gas-solids suspensions are limited by the low temporal or low spatial resolution of the sample volume, or in the case of optical methods, by a short range of sight. In this work, a sub-millimetre wave range-Doppler radar is developed and validated for non-intrusive sensing of solids concentrations in a gas-solids particle system with known characteristics. The radar system combines favourable features, such as the ability to see through at optical frequencies opaque materials, to measure the local solids velocity and the reflected radar power with a spatial resolution of a few cubic centimetres over distances of a few metres. In addition, the radar hardware offers flexibility in terms of installation. After signal processing, the output of the radar is range-velocity images of the solids flowing along the radar’s line-of-sight. The image frame rate can be close to real-time, allowing the solids flow dynamics to be observed. While the well-established Doppler principle is used to measure the solids velocity, this paper introduces a method to relate the received radar signal power to the solids volumetric concentrations (cv) of different particulate materials. The experimental set-up provides a steady stream of free-falling solids that consist of glass spheres, bronze spheres or natural sand grains with known particle size distributions and with particle diameters in the range of 50–300 µm. Thus, the values of cv found using the radar measurements are validated using the values of cv retrieved from closure of the mass balance derived from the measured mass flow rate of the solids stream and the solids velocity. The results show that the radar system provides reliable measurements of cv, with a mean relative error of approximately 25 % for all the tested materials, particle sizes and mass flow rates, yielding values of cv ranging from 0.2 × 10-4 m3/m3 up to 40 × 10-4 m3/m3 and solids velocities within the range of 0–4.5 m/s. This demonstrates the ability of the radar technology to diagnose the solids flow in gas-solids suspensions using a unique combination of penetration length, accuracy, and spatial and time resolution. In future work, the radar technique will be applied to study non-controlled solids flow at a larger scale, and to understand flow conditions relevant to industrial reactor applications, e.g., fluidised bed, entrained flow, and cyclone units.
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| 6. |
- Bonmann, Marlene, 1988, et al.
(författare)
-
Terahertz radar observes powder dynamics for pharmaceutical manufacturing
- 2024
-
Ingår i: IEEE Sensors Journal. - 1558-1748 .- 1530-437X. ; 24:13, s. 20512-20522
-
Tidskriftsartikel (refereegranskat)abstract
- The optical opaqueness of powders has precluded the observation of powder flow dynamics in processing tubes, with important implications, for example, in the pharmaceutical industry, where non-destructive monitoring during the manufacturing process is essential to ensure the quality of the final product and the effectiveness of the process. Taking advantage of the high penetration of terahertz electromagnetic waves in powders and its wavelength-to-particle size ratio, we demonstrate that a submillimeter-wave pulse-Doppler radar can overcome the present challenges and characterize powder flow dynamics in pharmaceutical manufacturing processes. Mimicking typical vessel shapes in pharmaceutical operations, we were able to characterize falling powder streams in a tube with a sample volume resolution of a few cubic centimeters and a range resolution of about 5 mm. We successfully monitored particle velocity, particle distribution within the tube, and mass flow rate in real-time. This remote sensing method, based on advanced terahertz electronics, opens up the possibility to study and monitor powder dynamics in a wide range of applications.
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| 7. |
- Borgström, Magnus, et al.
(författare)
-
InAs quantum dots grown on InAlGaAs lattice matched to InP
- 2003
-
Ingår i: Journal of Crystal Growth. - 0022-0248. ; 252:4, s. 481-485
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we present InAs quantum dots prepared on an InxAlyGa1-x-yAs surface by metal organic vapor phase epitaxy. Atomic force microscopy measurements indicate that dots grown on material with higher Al content are smaller, and that the local dot densities on step-bunched facets formed on the vicinal (0 0 1) surfaces increase. We find that these dots show luminescence at very long wavelengths, lambda(room temperature) approximate to 2.1 mum, and that the emission wavelengths are blue-shifted when the Al content is increased in the layer onto which dot material is deposited. (C) 2003 Elsevier Science B.V. All rights reserved.
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| 8. |
- Borgström, Magnus, et al.
(författare)
-
Site control of InAs quantum dots on a patterned InP surface: As/P exchange reactions
- 2003
-
Ingår i: Journal of Crystal Growth. - 0022-0248. ; 248, s. 310-316
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper. we present the effect of annealing temperature and annealing time on InAs site-controlled quantum dot growth. Individual InAs quantum dots formed by self-assembling have been positioned into holes, created by partial overgrowth of electron beam induced nano-carbon deposits by metal organic vapor phase epitaxy. As/P exchange reactions produce material sufficient for selective dot nucleation in the holes. Results. showing that As/P exchange reactions occur even when capping the dots with InP are presented. (C) 2002 Elsevier Science B.V. All rights reserved.
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| 9. |
- Borgström, Magnus, et al.
(författare)
-
Site-control of InAs quantum dots on a patterned InP surface: As/P exchange reactions
- 2002
-
Ingår i: 7th International Conference on Nanometer-Scale Science and Technology and 21st European Conference on Surface Science.
-
Konferensbidrag (refereegranskat)abstract
- We present the effect of annealing temperature and annealing time on InAs/InP site-controlled quantum dot growth. Electron beam pre-patterning forms carbon nano-deposits at the InP surface, which then can be used as growth masks to form nano-holes at the surface. By only annealing of the patterned InP surface under an arsine ambient, As/P exchange reactions produce material sufficient for selective dot nucleation in the holes at the surface
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| 10. |
- Bryllert, Tomas, et al.
(författare)
-
11% efficiency 100 GHz InP-based heterostructure barrier varactor quintupler
- 2005
-
Ingår i: Electronics Letters. - : Institution of Engineering and Technology (IET). - 0013-5194 .- 1350-911X. ; 41:3, s. 131-132
-
Tidskriftsartikel (refereegranskat)abstract
- A record conversion efficiency of 11.4% at 100 GHz using a heterostructure barrier varactor (HBV) quintupler is demonstrated. The quintupler is based on a microstrip circuit mounted in a full-height crossed-waveguide block. The nonlinear element consists of a planar HBV diode fabricated in InGaAs=InAlAs=AlAs epitaxial layers on an InP substrate.
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| 11. |
- Bryllert, Tomas, 1974, et al.
(författare)
-
220-GHz imaging radar with 1 Hz frame rate using an array of homodyne transceivers
- 2018
-
Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 10634
-
Konferensbidrag (refereegranskat)abstract
- We present a 220 GHz imaging radar prototype that has been developed in the European Defense Agency (EDA) project TIPPSI. The purpose of the development was to demonstrate short-range high-resolution 3D imaging for security applications at checkpoints, and to guide the development of stand-off real-time millimeter wave and sub-millimeter wave imaging systems for detection of larger objects at greater distances. An additional goal was to experimentally verify simulation techniques for active (sub)-mmw imaging systems, the verified simulation techniques can then be used to explore different system architectures. The 220 GHz imaging radar prototype consist of a flexible, mechanically scanned optical system that can support linear arrays of transmit/receive (TxRx) units up to 150 mm in length. The optical system is divided into two parts: A compact Dragonian system including the mechanical scanner that can be used as a stand-alone imager at reduced target distance and resolution, and a confocal system that can be added to achieve the full resolution of 1 cm x 1 cm x 1 cm at 4.5 m target distance. The field of view of the full resolution system is 70 cm x 70 cm. The front-end is currently populated by 4 TxRx units that are sparsely distributed along the 150 mm focal plane. The TxRx units operate in frequency modulated continuous wave (FMCW) mode and have a bandwidth of 24 GHz. Each TxRx unit use a single horn antenna and the transmit- and receive signals are generated and received using the same circuits which avoids the need of a duplexer. We will demonstrate high resolution 3D videos taken at 1 Hz frame rate and compare the individual images with simulations using electromagnetic simulators and character/clothes animation.
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| 12. |
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| 13. |
- Bryllert, Tomas, 1974, et al.
(författare)
-
A 175 GHz HBV Frequency Quintupler With 60 mW Output Power
- 2012
-
Ingår i: IEEE Microwave and Wireless Components Letters. - 1558-1764 .- 1531-1309. ; 22:2, s. 76-78
-
Tidskriftsartikel (refereegranskat)abstract
- In this letter, we present a fixed tuned 175 GHz frequency quintupler with 60 mW output power. The peak efficiency is 6.3% and the 3 dB bandwidth is 8 GHz. The multiplier is based on a single Heterostructure Barrier Varactor (HBV) diode that is flip-chip soldered into a microtsrip matching circuit. All the matching is done “on-chip” and there is no need for dc bias. The multiplier block is very compact (25 x 9 x 8 mm^3).
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| 14. |
- Bryllert, Tomas, 1974, et al.
(författare)
-
A broadband heterostructure barrier varactor tripler source
- 2010
-
Ingår i: 2010 IEEE MTT-S International Microwave Symposium (MTT). - 0149-645X. - 9781424460571 ; , s. 344-347
-
Konferensbidrag (refereegranskat)abstract
- We present the first demonstration of a broadband Heterostructure Barrier Varactor tripler, designed to cover a major part of the WR-8 waveguide band. The source comprises a waveguide housing, a six-barrier InP-HBV diode flip-chip mounted on an AlN microstrip filter circuit. The conversion loss 3-dB bandwidth was measured to 17 % at a center frequency of 112 GHz. The maximum output power was more than 15 mW for an input power of 300 mW. There are no mechanical tuners or DC-bias, which simplifies assembly and allows for ultra-compact design.
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| 15. |
- Bryllert, Tomas, 1974, et al.
(författare)
-
A High-Power Frequency Tripler for 100 GHz
- 2006
-
Ingår i: The Joint 31st International Conference on Infrared and Millimeter Waves and 14th International Conference on Terahertz Electronics. - 1424404002 ; , s. 30-
-
Konferensbidrag (refereegranskat)abstract
- We present a Heterostructure Barrier Varactor (HBV) based tripler for power generation at ~100 GHz. The matching circuit for the HBV diode is implemented in microstrip on an AlN substrate with the diode flip-chip soldered. The microstrip circuit is mounted in a waveguide configuration. To simplify the fabrication and assembly no DC ground is used and the waveguides are full-height. 130 mW of output power at 114 GHz is achieved without the use of any tuners.
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| 16. |
- Bryllert, Tomas, 1974, et al.
(författare)
-
A monolithic 280 GHz HBV frequency tripler
- 2010
-
Ingår i: IRMMW-THz 2010 - 35th International Conference on Infrared, Millimeter, and Terahertz Waves, Conference Guide. - 9781424466573
-
Konferensbidrag (refereegranskat)abstract
- We present the design and measurements of a Heterostructure Barrier Varactor based frequency tripler for 280 GHz. The tripler is fabricated as a monolithic circuit on an InP substrate, including the input and output waveguide probes. Several circuit versions for input power levels between 100 mW and 1W have been designed. © 2010 IEEE.
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| 17. |
- Bryllert, Tomas, 1974, et al.
(författare)
-
A Submillimeter-Wave FMCW Pulse-Doppler Radar to Characterize the Dynamics of Particle Clouds
- 2023
-
Ingår i: IEEE Transactions on Terahertz Science and Technology. - 2156-342X .- 2156-3446. ; 13:4, s. 389-395
-
Tidskriftsartikel (refereegranskat)abstract
- This work presents a 340-GHz frequency-modulated continuous-wave (FMCW) pulse-Doppler radar. The radar system is based on a transceiver module with about one milli-Watt output power and more than 30-GHz bandwidth. The front-end optics consists of an off-axis parabola fed by a horn antenna from the transceiver unit, resulting in a collimated radar beam. The digital radar waveform generation allows for coherent and arbitrary FMCW pulse waveforms. The performance in terms of sensitivity and resolution (range/cross-range/velocity) is demonstrated, and the system's ability to detect and map single particles (0.1–10 mm diameter), as well as clouds of particles, at a 5-m distance, is presented. A range resolution of ca 1 cm and a cross-range resolution of a few centimeters (3-dB beam-width) allow for the characterization of the dynamics of particle clouds with a measurement voxel size of a few cubic centimeters. The monitoring of particle dynamics is of interest in several industrial applications, such as in the manufacturing of pharmaceuticals and the control/analysis of fluidized bed combustion reactors.
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| 18. |
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| 19. |
- Bryllert, Tomas, et al.
(författare)
-
Designed emitter states in resonant tunneling through quantum dots
- 2002
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 80:15, s. 2681-2683
-
Tidskriftsartikel (refereegranskat)abstract
- Resonant tunneling through a single layer of self-assembled quantum dots (QDs) is compared to tunneling through two layers of vertically aligned (stacked) dots. The difference can be viewed as going from a two-dimensional emitter to a zero-dimensional emitter. The temperature dependence of current peaks originating in tunneling through individual QDs and individual stacks is used to clarify this point. In addition, we show that the statistical size distribution of self-assembled quantum dots causing the inhomogeneous broadening in luminescence experiments can be analyzed in a resonant tunneling experiment. (C) 2002 American Institute of Physics.
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| 20. |
- Bryllert, Tomas, 1974, et al.
(författare)
-
High Power HBV Multipliers
- 2007
-
Ingår i: 18th International Symposium on Space THz Technology.
-
Konferensbidrag (refereegranskat)abstract
- We present a high-power frequency tripler for 100 GHz. The tripler - that is based on a single HBV diode - produces >200 mW of output power with a 3-dB bandwidth of 6%. This is the highest output power ever recorded for an HBV based multiplier irrespective of output frequency. The module features an ultra-compact waveguide block design and a microstrip matching circuit on high-thermal-conductivity AlN to improve the power handling capability.
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| 21. |
- Bryllert, Tomas, 1974, et al.
(författare)
-
Integrated 200–240-GHz FMCW Radar Transceiver Module
- 2013
-
Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480 .- 1557-9670. ; 61:10, s. 3808-3815
-
Tidskriftsartikel (refereegranskat)abstract
- We present a 220-GHz homodyne transceiver module intended for frequency modulated continuous wave radar applications. The RF transceiver circuits are fabricated on 3 µm-thick GaAs membranes, and consist of a Schottky diode based transmitter frequency doubler that simultaneously operates as a sub-harmonic downconverting mixer. Two circuits are used in a balanced configuration to improve the noise performance. The output power is >3 dBm over a 40-GHz bandwidth (BW) centered at 220 GHz, and the receiver function is characterized by a typical mixer conversion loss of 16 dB. We present radar images at 4-m target distance with up to 60-dB dynamic range using a 30-µs chirp time, and near-BW-limited range resolution. The module is intended for applications in high-resolution real-time 3-D radar imaging, and the unit is therefore designed so that it can be assembled into 1-D or 2-D arrays.
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| 22. |
- Bryllert, Tomas, et al.
(författare)
-
Resonant tunneling through coupled self-assembled quantum dots and the influence of inhomogeneous broadening
- 2002
-
Ingår i: 7th International Conference on Nanometer-Scale Science and Technology and 21st European Conference on Surface Science.
-
Konferensbidrag (refereegranskat)abstract
- Resonant tunneling through a single layer of self-assembled quantum dots (QDs) as well as tunneling through two layers of vertically aligned (stacked) dots is investigated. The difference between single and double layers of QDs can be viewed as going from a two-dimensional emitter to a zero-dimensional emitter. By fabricating small-area devices we are able to probe single stacks of quantum dots, revealing details of the coupling between the stacked dots. Very sharp resonances, with peak-to-valley ratios of several hundred, have been measured in the current-voltage characteristics. We also show that the statistical size distribution of self-assembled quantum dots causing the inhomogeneous broadening in luminescence experiments can be analysed in a resonant tunneling experiment
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| 23. |
- Bryllert, Tomas, 1974
(författare)
-
Sub-millimeter wave diode transceivers
- 2014
-
Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. - 9781479938773 ; , s. Art. no. 6956019-
-
Konferensbidrag (refereegranskat)abstract
- We present sub-millimeter wave transceiver modules intended for imaging radar applications. In particular a novel circuit architecture that operates in homodyne FMCW radar mode will be highlighted [1], and the trade-offs between performance and circuit complexity will be discussed. The transceiver units are based on monolithically integrated Schottky diodes fabricated on 3 μm thick membranes. Radar images with 60 dB of signal-to-noise at 220 GHz will be presented as well as design results for a 340 GHz unit.
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| 24. |
- Bryllert, Tomas, et al.
(författare)
-
Transport through an isolated artificial molecule formed from stacked self-assembled quantum dots
- 2003
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 82:16, s. 2655-2657
-
Tidskriftsartikel (refereegranskat)abstract
- We investigate resonant tunneling through two coupled self-assembled quantum dots. The strong confinement and the high crystalline quality provided by the self-assembled dots, in combination with the tunneling coupling between the dots, create a system that may be thought of as an artificial molecule. We are able to isolate one single artificial molecule and detailed investigations of the electrical properties are performed. Peak-to-valley ratios above 1000 and full width half maximum of a few millivolts are measured at 4 K. By changing the temperature we also observe Coulomb blockade effects in a different way. (C) 2003 American Institute of Physics.
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| 25. |
- Bryllert, Tomas, et al.
(författare)
-
Vertical high-mobility wrap-gated InAs nanowire transistor
- 2006
-
Ingår i: IEEE Electron Device Letters. - 0741-3106 .- 1558-0563. ; 27:5, s. 323-325
-
Tidskriftsartikel (refereegranskat)abstract
- In this letter, the authors demonstrate a vertical wrap-gated field-effect transistor based on InAs nanowires [Proc. DRC, 2005, p. 157]. The nanowires have a diameter of 80 nm and are grown using selective epitaxy; a matrix of typically 10 x 10 vertically standing wires is used as channel in the transistor. The authors measure current saturation at V-ds = 0.15 V (V-g = 0 V), and a high mobility, compared to the previous nanowire transistors, is deduced.
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| 26. |
- Bryllert, Tomas, et al.
(författare)
-
Vertical high mobility wrap-gated InAs nanowire transistor
- 2005
-
Ingår i: 63rd Device Research Conference Digest, 2005. DRC '05. - 0780390407 ; 1
-
Konferensbidrag (refereegranskat)abstract
- We demonstrate a wrap-gated field effect transistor based on a matrix of vertically standing InAs nanowires (Jensen, et. al., 2004). A lower limit of the mobility, derived from the transconductance, is on the order of 3000 cm2/Vs. The narrow ~100 nm channels show excellent current saturation and a threshold of Vg = -0.15 V. The sub-threshold characteristics show a close to ideal slope of 62mV/decade over two orders of magnitude
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| 27. |
- Bryllert, Tomas
(författare)
-
Vertical III-V Semiconductor Devices
- 2005
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis is based on three projects that deal with vertical III-V semiconductor devices. The work spans over basic research as well as more applied aspects of III-V semiconductor technology. All projects have in common that they rely on advanced epitaxial growth to form the starting material for device fabrication.In chapter two, zero-dimensional Quantum Dots (QDs) are incorporated into electronic devices to form resonant tunneling diodes. Single QDs, that can be viewed as artificial atoms, as well as coupled quantum dots, that can be viewed as artificial molecules, are investigated. Resonant tunneling diodes with a peak-to-valley-ratio of over 1000 at T=4K were fabricated and attempts were made to use the devices as spectrometers for terahertz radiation.In chapter three, InAs nanowires are used for fabrication of wrap-gated Field Effect Transistors (FETs). The combination of bottom-up fabricated, position controlled, InAs nanowires, and a processing scheme where the transistors are fabricated using a matrix of vertical wires, introduce a new type of device. High electron mobility and good current saturation is measured.Finally, in the fourth chapter, Heterostructure Barrier Varactor (HBV) diodes are fabricated and mounted in a frequency multiplier circuit. HBV diodes consist of a series of semiconductor layers where a high-bandgap material is sandwiched between layers of lower bandgap material. This results in a device with a non-linear differential capacitance that can create harmonics of an input signal. In this work a frequency quintupler (x5) from 20 GHz to 100 GHz is demonstrated, and a record conversion efficiency of 11.4% is achieved.
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| 28. |
- Bryllert, Tomas
(författare)
-
Vertical wrap-gated nanowire FETs
- 2005
-
Ingår i: Proc 1st Intl Symp on Semicond Nanowires, Lund, Sweden (2005).
-
Konferensbidrag (refereegranskat)
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| 29. |
- Bryllert, Tomas, et al.
(författare)
-
Vertical wrap-gated nanowire transistors
- 2006
-
Ingår i: Nanotechnology. - 0957-4484. ; 17:11, s. 227-230
-
Tidskriftsartikel (refereegranskat)abstract
- We present a process for fabricating a field-effect transistor based on vertically standing InAs nanowires and demonstrate initial device characteristics. The wires are grown by chemical beam epitaxy at lithographically defined locations. Wrap gates are formed around the base of the wires through a number of deposition and etch steps. The fabrication is based on standard III - V processing and includes no random elements or single nanowire manipulation.
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| 30. |
- Dahlbäck, Robin, 1985, et al.
(författare)
-
A 340 GHz CW non-linear imaging system
- 2010
-
Ingår i: Infrared Millimeter and Terahertz Waves (IRMMW-THz), 2010. - 9781424466559
-
Konferensbidrag (refereegranskat)abstract
- A CW sub-millimetre wave imaging system is presented. The system operates around 340GHz with a 6.5% relative bandwidth and uses a non-linear imaging algorithm.
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| 31. |
- Dahlbäck, Robin, 1985, et al.
(författare)
-
Compact 340 GHz homodyne transceiver modules for FMWC imaging radar arrays.
- 2016
-
Ingår i: IEEE MTT-S International Microwave Symposium Digest. - 0149-645X. ; 2016-August
-
Konferensbidrag (refereegranskat)abstract
- We present a solution where one single LO chain is used to feed a homodyne FMCW radar transceiver. An InGaAs pHEMT active frequency multiplier MMIC (x8) and a Schottky diode frequency doubler make up the LO chain. The novel Schottky diode based transceiver operates both as a frequency multiplier (x2) and as a sub-harmonic mixer. The modules operate at a center frequency of 340 GHz with a 30 GHz modulation bandwidth. An output power of 0 dBm, an IF noise level of -168 dBm/Hz and a receiver conversion loss of 18 dB is achieved in the band. The form factor of the modules is adapted to build one- or two- dimensional FMCW radar arrays. State of the art system performance is achieved while system complexity, size and cost is significantly reduced.
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| 32. |
- Drakinskiy, Vladimir, 1977, et al.
(författare)
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Development of planar schottky diodes
- 2011
-
Ingår i: 22nd International Symposium on Space Terahertz Technology 2011, ISSTT 2011; Tucson, AZ; United States; 25 April 2011 through 28 April 2011. ; , s. 64-
-
Konferensbidrag (refereegranskat)abstract
- We present the development of an air-bridged planar Schottky diode process at Chalmers University of Technology for use in submillimeter wave mixer and multiplier circuits. As a first step evaluation has been targeted for heterodyne receivers (atmosphere sounders) operation at 340 GHz. The aim is to develop a reliable and repeatable discrete Schottky diode process, with good electrical and mechanical characteristics, which also can be scaled to smaller anodes and extended to integrated diode circuits for THz frequencies. Air-bridged Schottky structures were demonstrated in the late 1980's as a reliable, high quality alternative to whisker contacted diodes. This approach gives a mechanically stable structure and still low parasitic capacitances. The Chalmers diode process is based on electron beam lithography, with a beam spot less than 5 nm, which allows for precise anode and airdridge formation. Hence, this process module can also be utilized for submicron size anodes and. terahertz monolithic integrated circuits (TMICs). Several batches with different shapes of anodes have been fabricated and evaluated with respect to DC/RF-performance. Repeatability of the diode's characteristics indicates good control of the diode fabrication process. We will present the main fabrication route, optimization and repeatability of the diodes as well as RF results from mixer and multiplier measurements up to 340 GHz.
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| 33. |
- Drakinskiy, Vladimir, 1977, et al.
(författare)
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Development of planar THz Schottky diodes
- 2011
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Ingår i: 6th ESA Workshop on Millimetre-Wave Technology and Applications.
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Konferensbidrag (refereegranskat)abstract
- We present the technological development of the air bridge planar Schottky diode process at Chalmers University of Technology for the use as submillimeter wave mixer and multiplier. Our first evaluation is targeted for the heterodyne receivers (i.e. atmosphere sounders) operation at 340 GHz. The aim is to develop a reliable and repeatable Schottky diode process, with good electrical and mechanical characteristics. In addition, the scalability of the diode geometry for diode integration in THz circuits is also taken into account in this development.
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| 34. |
- Drakinskiy, Vladimir, 1977, et al.
(författare)
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Status and Progress of Schottky Technology Development for SWI and ISMAR
- 2015
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Ingår i: 26th International Symposium on Space Terahertz Technology, ISSTT 2015; Cambridge; United States; 16 March 2015 through 18 March 2015. ; , s. P-6
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Konferensbidrag (refereegranskat)abstract
- We present the progress of the technological development of a full e-beam based monolithically integrated Schottky diode process applicable for sub-millimetre wave multipliers and mixers. The process has been employed in a number of demonstrators showing state-of-the-art performance.
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| 35. |
- Drakinskiy, Vladimir, 1977, et al.
(författare)
-
Terahertz GaAs Schottky diode mixer and multiplier MIC’s based on e-beam technology
- 2013
-
Ingår i: Conference Proceedings - International Conference on Indium Phosphide and Related Materials. - 1092-8669. - 9781467361316
-
Konferensbidrag (refereegranskat)abstract
- We present the progress of the technological development of a full e-beam based monolithically integrated Schottky diode process applicable for sub-millimetre wave multipliers and mixers. Evaluation of the process has been done in a number of demonstrators showing state-of-the-art performance, including various multiplier circuits up to 200 GHz with a measured flange efficiency of above 35%, as well as heterodyne receiver front-end modules operating at 340 GHz and 557 GHz with a measured receiver DSB noise temperature of below 700 K and 1300 K respectively.
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| 36. |
- Emadi, Arezoo, 1977, et al.
(författare)
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Design, Fabrication and characterisation of High Power HBV Diodes
- 2005
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Ingår i: 16th International Symposium on Space Terahertz Technology; Chalmers Conference Centre, May 2-4, 2005, Gothenburg, Sweden, (Eds. Jan Stake, Harald Merkel.). ; , s. Session: P05-04
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Konferensbidrag (refereegranskat)abstract
- We present design and analysis of material structures and device geometries for heterostructure barrier varactor diodes (HBVs) for high-power frequency multipliers. The methods aim at finding optimum epitaxial layer structures with respect to diode power handling capability and efficiency. A distributed device geometry for further increasing the output power levels whilst maintaining acceptable device temperatures is also presented. Finally, an electro-thermal HBV model with the ability of incorporating temperature-dependent device parameters is used to simulate the introduced devices, followed by a design example of a 3×4-barrier high-power HBV diode.
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| 37. |
- Emadi, Arezoo, 1977, et al.
(författare)
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High power HBV multipliers for F- and G- band applications
- 2004
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Ingår i: IRMMW 2004/THz 2004 / M. Thumm, W. Wiesbeck. - 0780384903 ; , s. 319-320
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Konferensbidrag (refereegranskat)abstract
- Progress and realisation of applications in the 100-240 GHz region is inhibited by the lack of high-power sources. Therefore, in an effort to reach watts of output power, we have tailored devices, circuits, materials, and design and fabrication methods for improved thermal management and high overall conversion efficiencies.
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| 38. |
- Emadi, Arezoo, 1977, et al.
(författare)
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Optimum Barrier Thickness Study for the Heterostructure Barrier Varactror Diode
- 2006
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Ingår i: WOCSDICE 2006. - 1652-0769. ; , s. 55-57
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Konferensbidrag (refereegranskat)abstract
- This experimental study aims at finding the optimum barrier thickness in heterostructure barrier varactor (HBV) diodes, to improve the diode efficiency especially for high-power frequency multiplier applications. The influence of barrier thickness on the conduction current is investigated for different biases and device temperatures. We found that for an InP-based HBV, there is an optimum barrier thickness range between 10 to 14 nm which causes the lowest possible leakage current.
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| 39. |
- Emadi, Arezoo, 1977, et al.
(författare)
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Optimum barrier thickness study for the InGaAs/InAlAs/AlAs heterostructure barrier varactor diodes
- 2007
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 90:1, s. 012108-3
-
Tidskriftsartikel (refereegranskat)abstract
- This experimental study aims at finding the optimum barrier thickness in heterostructure barrier varactor (HBV) diodes to improve the diode efficiency especially for high-power frequency multiplier applications. The influence of barrier thickness on the destructive current leaking over and through the barrier is investigated for different biases and operating temperatures. The authors found that for an InP-based HBV, there is an optimum barrier thickness range between 10 to 14 nm which causes the lowest possible leakage current.
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| 40. |
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| 41. |
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| 42. |
- Fröberg, Linus, et al.
(författare)
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Vertical InAs nanowire wrap-gate FETs
- 2006
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Ingår i: Book of abstracts: Semicond Nanowires Symp, Eindhoven, The Netherlands (2006).
-
Konferensbidrag (refereegranskat)
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| 43. |
- Gandini, E., et al.
(författare)
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On the development of a quasi-optical system for short and long range standoff imagers
- 2015
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Ingår i: 40th International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz 2015, Hong Kong, China, 23-28 August. - 2162-2027. - 9781479982721
-
Konferensbidrag (refereegranskat)abstract
- The European Defense Agency project TIPPSI aims to produce a phenomenology study to evaluate the performance of standoff imagers for security applications at submillimeter frequencies. In this context, a modular optical architecture is being developed. It is composed by a compact Dragonian system to image at short ranges coupled to a confocal system that operates at a larger focusing distance. The performance of the two solutions is described in this contribution.
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| 44. |
- Gandini, E., et al.
(författare)
-
Optomechanical System Design for Dual-Mode Stand-Off Submillimeter Wavelength Imagers
- 2017
-
Ingår i: IEEE Transactions on Terahertz Science and Technology. - : Institute of Electrical and Electronics Engineers (IEEE). - 2156-342X .- 2156-3446. ; 7:4, s. 393-403
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, the practical tradeoffs for designing submillimeter wavelength imagers based on optomechanical systems combined with focal plane arrays (FPAs) are presented. The architecture of these systems differs for operation at short and long ranges. General formulas to derive the effective field of view of diffraction limited quasi-optical systems in these two scenarios are shown. These formulas can be used to evaluate the performance of a specific optical system implementation. As an application example, we present the design of an optomechanical system that can operate at both ranges in a modular approach. The presented implementation achieves an effective field of view, which is 70% of the canonical one. The proposed solution consists of a linear FPA of eight active transceivers combined with a raster scan technique. The system for short-range scenario is a side-fed dual-reflector Dragonian architecture because of its good scanning performance when illuminated by an FPA. Thanks to the system's small aperture, the scanner is arranged after the primary mirror, without causing additional scan loss. The Dragonian system is then used to illuminate a confocal dual-reflector architecture to magnify its aperture, and can be used in the long-range scenario. The scanner in this case is before the main aperture and it has to be considered in the performance optimization of the optical system since it adds phase aberration loss.
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| 45. |
- Guio Perez, Diana Carolina, 1985, et al.
(författare)
-
Radar-based measurements of the solids flow in a circulating fluidized bed
- 2023
-
Ingår i: Fuel. - 0016-2361. ; 345
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this work is to demonstrate the value of radar technology for studying experimentally the solids flows in gas-solids fluidized beds. The work presents original results regarding the solids concentration and velocity acquired in a non-intrusive manner from a cold flow model. The tailored radar setup operates at submillimeter wave frequencies (0.34 THz) and can measure the location of solids with a spatial resolution of 1/8 mm−1 in the direction of the radar beam, and of 40–60 mm across the radar beam. The solids velocity in the direction of the beam propagation is determined through measurement of the Doppler shift caused by the reflection of the transmitted radar signal by solids moving in relation to the antenna. The measurements were performed in both the horizontal and vertical directions in the riser of a circulating fluidized bed (cross-sectional area of 0.45 m2 and height of 3.1 m) operated with glass beads (mean particle size of 106 µm, and particle density of 2,486 kg/m3) and using air at ambient temperature as the fluidization agent, with superficial velocities in the range of 0.3–1.3 m/s. The measurements are used to assess the validity of the technique and are not intended to characterize the unit fluid dynamically. The solids concentrations derived from the radar measurements follow the qualitative trends derived from pressure-drop measurements, resembling the expected changes that occur in the concentration profiles as the fluidization velocity increases. Concentrations in the range from 10-6 m3/m3 to 10-1 m3/m3 are measurable. In quantitative terms, for low concentrations of solids (<5·10-3 m3/m3, approximately) the radar measurements exhibited the ability to provide more consistent measurements of the solids concentration than those obtained from pressure transducers, for which the small pressure differences lead to unstable and even negative values for solids concentrations. The two measurement methods were in quantitative agreement for solids volume fractions higher than the threshold. Concentrations ≥ 1·10-1 m3/m3, though measurable, strongly attenuate the radar signal, thereby reducing the beam penetration to a depth of centimeters. For each position along the radar beam, the distribution of solids velocity measured from the Doppler effect was found to be within the expected ranges and allowed observations of solids back-mixing. The radar technique applied in this work is a promising technique for detailed characterization of the solids flow in fluidized beds, offering high spatial and temporal resolutions, allowing the determination of both solids velocity and concentration, and having a reasonably high penetration depth.
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| 46. |
- Hanning, Johanna, 1981, et al.
(författare)
-
A Broadband THz Waveguide-to-suspended Stripline Loop-probe Transition
- 2017
-
Ingår i: IEEE MTT-S International Microwave Symposium Digest. - 0149-645X. - 9781509063604 ; , s. 1091-1094
-
Konferensbidrag (refereegranskat)abstract
- We present a novel waveguide-to-suspended stripline loop-probe transition operating over the entire WR-1.0 waveguide band. The loop probe is designed for broadband response with simulated RL > 15 dB, and has an integrated DC return path, which can also be extended for biasing. The measured insertion loss for a back-to-back configuration is 1 – 2 dB in almost the entire frequency range of 750 – 1100 GHz.
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| 47. |
- Hanning, Johanna, 1981, et al.
(författare)
-
HBV MMIC frequency tripler and quintupler for high power THz applications
- 2011
-
Ingår i: Millimetre Wave Days Proceedings,The 6th ESA Workshop on Millimetre-Wave Technology and Applications AND The 4th Global Symposium on Millimeter Waves GSMM2011, May 23rd – May 25th, 2011, MilliLab, Espoo, Finland.
-
Konferensbidrag (refereegranskat)abstract
- We present the development status of two different HBV frequency multipliers, with x3 and x5 multiplication for a 282 GHz and 470 GHz output respectively. The multipliers are designed for high power operation and fabricated in an InP monolithic process. Preliminary measurements of the x3 multiplier demonstrate 10 % conversion efficiency at 296 GHz.
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| 48. |
- Hanning, Johanna, 1981, et al.
(författare)
-
Single Flange 2-port Design For THz Integrated Circuit S-parameter Characterization
- 2013
-
Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. ; , s. 1-2
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Konferensbidrag (refereegranskat)abstract
- A single flange 2-port TRL calibration and measurement setup for accurate THz S-parameter characterization of integrated membrane circuit devices is proposed. The proposed setup facilitates shorter access waveguides, which greatly improves the calibration uncertainty.
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| 49. |
- Hanning, Johanna, 1981, et al.
(författare)
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Single-Flange 2-Port TRL Calibration for Accurate THz S-Parameter Measurements of Waveguide Integrated Circuits
- 2014
-
Ingår i: IEEE Transactions on Terahertz Science and Technology. - 2156-342X .- 2156-3446. ; 4:5, s. 582-587
-
Tidskriftsartikel (refereegranskat)abstract
- This paper describes a single flange 2-port measurement setup for S-parameter characterization of waveguide integrated devices. The setup greatly reduces calibration and measurement uncertainty by eliminating vector network analyzer (VNA) extender cable movement and minimizing the effect of waveguide manufacturing tolerances. Change time of standards is also improved, reducing the influence of VNA drift on the uncertainty. A TRL calibration kit has been manufactured and measurements are demonstrated in WR-03 (220–325 GHz).
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| 50. |
- Jonsson, Robert, 1989, et al.
(författare)
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Experimental Analysis of a Clutter Suppression Algorithm for High Time-Bandwidth Noise Radar
- 2023
-
Ingår i: Proceedings of the IEEE Radar Conference. - : Institute of Electrical and Electronics Engineers (IEEE). - 2375-5318 .- 1097-5764.
-
Konferensbidrag (refereegranskat)abstract
- Noise-like, continuous waveforms have several benefits for radar operation, such as low probability of interception/identification. However, the same types of waveforms come with a significant drawback because strong signals, e.g., ground clutter, produce a correlation noise floor (CNF) that masks all weak signals. In this article, we report on the implementation and performance of an efficient clutter suppression algorithm used to suppress strong clutter echoes and allow for the detection of weaker signals. The algorithm's performance is verified using an experimental system with a time-bandwidth product of 70 dB at a centre frequency of 1.3 GHz. Application of the algorithm suppresses the CNF by over 30 dB, allowing for the detection of an unmanned aerial vehicle (UAV).
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