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- Brihuega, Alberto, et al.
(author)
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On the Power and Beam Dependency of Load Modulation in mmWave Active Antenna Arrays
- 2020
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In: 2020 50TH EUROPEAN MICROWAVE CONFERENCE (EUMC). - 2325-0305.
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Conference paper (peer-reviewed)abstract
- Linearization of active antenna arrays is gaining increasing interest due to their wide applicability in 5G New Radio (NR) networks. As direct access to the output ports of the power amplifiers (PAs) in highly integrated millimeter-wave (mmW) active arrays is difficult, different over-the-air (OTA) digital predistortion (DPD) solutions have been recently proposed. Large majority of such solutions build on the assumption that the nonlinear behaviors of the parallel PA units are independent of the beam direction. However, in this paper, we show through comprehensive OTA measurements on a commercial 64-element active array operating at 28 GHz, that the nonlinear distortion characteristics and the involved load modulation phenomenon largely depend on the beam direction as well as on the considered transmit power, and also that the beam-dependence increases with increasing transmit power. The findings of the measurements are also connected to the state-of-the-art PA models, paving the way towards the development of more efficient DPD solutions and the associated parameter learning methods for mmW active antenna array transmitters.
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| 4. |
- Chani Cahuana, Jessica, 1988, et al.
(author)
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Structured Digital Predistorter Model Derivation Based on Iterative Learning Control
- 2016
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In: 2016 46th European Microwave Conference. - 2325-0305. - 9782874870439 ; , s. 178-181
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Conference paper (peer-reviewed)abstract
- A novel approach to derive model structures for digital predistorters based on iterative learning control (ILC) is presented. ILC is a technique used to identify the optimal PA input signal/predistorted signal that drives a PA to a desired output response. The ILC concept is used to derive an analytical expression of the predistorted signal and to identify basis functions for predistorter models. The proposed approach is used to derive a predistorter model structure from the memory polynomial model. Experimental results show that the predistorter model derived with the proposed approach can obtain better linearity performance than conventional models used in digital predistortion.
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| 5. |
- Fager, Christian, 1974, et al.
(author)
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IC Design Aspects for 5G mm-Wave Systems
- 2020
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In: 2020 50TH EUROPEAN MICROWAVE CONFERENCE (EUMC). - 2325-0305. - 9782874870590 ; , s. 870-871
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Conference paper (other academic/artistic)
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| 6. |
- Jayasankar, Divya, et al.
(author)
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Investigation of Hydrogel Skin Phantoms Using Terahertz Time-domain Spectroscopy
- 2022
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In: 2022 52nd European Microwave Conference, EuMC 2022. - : Institute of Electrical and Electronics Engineers Inc.. - 9782874870699 ; , s. 401-403
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Conference paper (peer-reviewed)abstract
- Human skin phantoms are essential to enable fast, label-free, and reliable testing of pharmaceutical and cosmetic products. We report the characterisation of polyvinyl alcohol-based hydrogel phantoms along with in-vivo skin measurements of three volunteers from 0.2 to 1 THz. The results indicate that frequency-dependent properties of hydrogel phantoms are similar to human skin and show promising prospects of being utilised as a skin equivalent.
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| 7. |
- Robertson, D. A., et al.
(author)
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A 220 GHz 3D imaging radar with sub-cm voxel resolution for security applications
- 2016
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In: 2016 46th European Microwave Conference (EuMC); London, England; 4-6 oct, 2016. - 2325-0305. ; , s. 1545-1548, s. 398-401
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Conference paper (peer-reviewed)abstract
- Radars operating at high millimetre and sub millimetre wave frequencies are promising candidates for security applications such as people screening since they offer the possibility to form 3D images through clothing with sufficient resolution to detect concealed objects. High spatial resolution of order 1 cm can be achieved using practically sized antennas and high range resolution can be achieved using wideband FMCW chirps, e.g. 30 GHz, to yield 0.5 cm range bins. We present a 220 GHz test-bed 'Pathfinder' radar which achieves sub-cm(3) voxel resolution with very high signal fidelity. The radar is used to de risk technology under development for next generation people screening systems.
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