| 1. |
- Ankel, Martin, 1996, et al.
(författare)
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Bistatic noise radar: Demonstration of correlation noise suppression
- 2023
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Ingår i: IET Radar, Sonar and Navigation. - : Institution of Engineering and Technology (IET). - 1751-8792 .- 1751-8784. ; 17:3, s. 351-361
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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)
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Experimental Evaluation of Moving Target Compensation in High Time-Bandwidth Noise Radar
- 2023
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Ingår i: 20th European Radar Conference, EuRAD 2023. ; , s. 213-216
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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)
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Experimental Evaluation of Moving Target Compensation in High Time-Bandwidth Noise Radar
- 2023
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Ingår i: Proceedings 20th European Radar Conference (EuRAD). - : Institute of Electrical and Electronics Engineers (IEEE). ; , s. 213-216
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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)
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Implementation of a coherent real‐time noise radar system
- 2023
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Ingår i: IET radar, sonar & navigation. - : Institution of Engineering and Technology (IET). - 1751-8784 .- 1751-8792.
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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)
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Sub-millimetre wave range-Doppler radar as a diagnostic tool for gas-solids systems - solids concentration measurements
- 2023
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Ingår i: Advanced Powder Technology. - : Elsevier BV. - 0921-8831 .- 1568-5527. ; 34:1
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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)
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Terahertz radar observes powder dynamics for pharmaceutical manufacturing
- 2024
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Ingår i: IEEE Sensors Journal. - 1558-1748 .- 1530-437X. ; 24:13, s. 20512-20522
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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)
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InAs quantum dots grown on InAlGaAs lattice matched to InP
- 2003
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Ingår i: Journal of Crystal Growth. - 0022-0248. ; 252:4, s. 481-485
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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)
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Site control of InAs quantum dots on a patterned InP surface: As/P exchange reactions
- 2003
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Ingår i: Journal of Crystal Growth. - 0022-0248. ; 248, s. 310-316
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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)
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Site-control of InAs quantum dots on a patterned InP surface: As/P exchange reactions
- 2002
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Ingår i: 7th International Conference on Nanometer-Scale Science and Technology and 21st European Conference on Surface Science.
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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)
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11% efficiency 100 GHz InP-based heterostructure barrier varactor quintupler
- 2005
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Ingår i: Electronics Letters. - : Institution of Engineering and Technology (IET). - 0013-5194 .- 1350-911X. ; 41:3, s. 131-132
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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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