B. Cimbili, C. Friesicke, F. Van Raay, S. Wagner, M. Bao and R. Quay, “High-Efficiency Watt-Level E-band GaN Power Amplifier with a Compact Low-loss Combiner”
Abstract: This paper presents a 3-stage E-band (71–83 GHz) power amplifier (PA) that employs a compact low-loss distributed matching network (DMN), which performs both the output matching and power combining. As a result of this, the measured PA achieves an output power of 30.4 dBm ± 0.9 dB (1.12 W ± 0.23 W) across the band. The PA achieves a peak output power of 1.35 W with a power-added efficiency (PAE) of 20.8% and a power gain of 16.3 dB at 78 GHz. The associated power density is 1.87 W/mm. When biased with 10V supply voltage, a peak PAE of 25% is reached. To the best of the authors’ knowledge, the peak PAE with the power gain and associated power density are the highest values reported in GaN technologies at E-band.
2023 IEEE Topical Conference on RF/Microwave Power Amplifiers for Radio and Wireless Applications, Las Vegas, NV, USA, 2023, pp. 42-44, doi: 10.1109/PAWR56957.2023.10046243.
Y. Zhang, A. R. Vilenskiy and M. V. Ivashina, “Mutual Coupling Analysis of Open-Ended Ridge and Ridge Gap Waveguide Radiating Elements in an Infinite Array Environment”
Abstract: In this paper, we discuss mutual coupling effects in 2-D beam-steerable antenna arrays based on open-ended ridge and ridge gap waveguide radiating elements. Considering potential applications for beyond-5G systems in W-/D-band, the radiating elements are designed full-metal realizing a high radiation efficiency. Various decoupling structures based on electromagnetic soft surfaces are applied to suppress the surface waves over the array apertures. The infinite array approach is used to analyze antenna unit cells in an isosceles triangular lattice, which results in the active reflection coefficient over a scan and frequency range. The latter is used to extract the values of the mutual coupling coefficients between the elements. The analysis demonstrates the effect of decoupling structures realizing a steep drop of the mutual coupling magnitude (≤ − 20 dB) for closely-spaced array elements. This results in a wideband (≥ 20%) and wide-scan (> 50°) element beam-steering performance.
2022 52nd European Microwave Conference (EuMC), Milan, Italy, 2022, pp. 696-699, doi: 10.23919/EuMC54642.2022.9924388.
J. Banar and T. Eriksson, “Effect of Phase-Noise on the Distributed Massive MIMO Networks”
Abstract: We study the effect of phase noise on the achievable spectral efficiency (SE) of a distributed massive multi-input multiple-output (DM-MIMO) network. We obtain a closed-form expression for this network considering the phase noise, independent Rayleigh fading channel, and minimum mean square error (MMSE) channel estimation. In this network, Access points (APs) under the time-division duplex (TDD) operation estimate the channels via the uplink training phase and transmit the downlink data. The equations and simulation results present the effect of phase noise introduced by oscillators in APs. Results show the impact of phase noise at APs on the achievable SE. Consequently, we observe that in the DM-MIMO network, with increasing the number of UEs, PN causes some degradation in the SE. On the other hand, with increasing the variance of the PN, the SE decreases. Through simulations, we verify our analytical results and closed-form equations.
2022 52nd European Microwave Conference (EuMC), Milan, Italy, 2022, pp. 700-703, doi: 10.23919/EuMC54642.2022.9924329.
N. Farid, A. Hubrechsen, J. Fridén, U. Johannsen, A. B. Smolders and L. A. Bronckers, “A mm-Wave Hybrid Stirring Technique for Over-the-Air Testing in Reverberation Chambers”
Abstract: Over-the-Air methodologies are the potential solutions for the characterization of next-generation wireless devices that rely on the emulation of a realistic channel model in a controlled laboratory environment. A highly attractive concept is the hybrid chamber, combining properties of anechoic chambers and reverberation chambers. By altering the mechanical stirrers of a mm-Wave reverberation chamber, a novel loading condition to achieve a directive channel for 5G NR FR2 applications is proposed: a hybrid stirrer. This is done by partly covering the stirrers with radio-frequency absorbers, as a first step towards a hybrid chamber. In future generations, this may be used to intentionally break uniformity in a controlled manner. Moreover, a more conventional loading configuration is investigated as a counterpart. A spatial uniformity study based on the chamber’s power transfer function measurements is carried out for two case scenarios. It has been shown that the proposed configurations are capable of altering spatial uniformity, giving 0.52 dB and 1.46 dB for the conventional and hybrid stirrer method, respectively. Both result in a frequency-flat channel with the required coherence bandwidth for the successful demodulation of the signals.
2022 52nd European Microwave Conference (EuMC), Milan, Italy, 2022, pp. 704-707, doi: 10.23919/EuMC54642.2022.9924396.
Husileng Bao, Zhongxia Simon He, Filippo Ponzini, Christian Fager, “Demonstration of Flexible mmWave Digital Beamforming Transmitter using Sigma-Delta Radio-Over-Fiber Link”
Abstract: This work demonstrates a millimeter-wave digital beamforming transmitter based on a sigma-delta radio-over-fiber link. The digital beamforming is controlled from a central unit and distributed to a remote radio unit using a standardized quad small form-factor pluggable 28 (QSFP28) fiber connection. The experimental results demonstrate 26.2 GHz transmission with high-quality beamforming functionality up to 130 MHz effective radio bandwidth at 2.2 m wireless distance. The solution offers a flexible transmitter solution suitable for millimeter-wave distributed active antenna systems.
2022 52nd European Microwave Conference (EuMC), Milan, Italy, 2022, pp. 692-695, doi: 10.23919/EuMC54642.2022.9924386.
Kateryna Smirnova, Mehmet Kaynak, Ahmet Çağri Ulusoy, “A W-band Low-Power Gilbert Cell Mixer with Image Rejection in 130-nm SiGe BiCMOS Technology”
Abstract: This paper presents a 100-GHz Gilbert cell down-conversion mixer with an integrated image rejection functionality, implemented in a 0.13-µm SiGe BiCMOS technology. The maximum measured conversion gain is 3.7 dB with an LO power of only −10 dBm, while the image rejection ratio (IRR) is 38 dBc at an RF frequency of 100 GHz. The circuit consumes 8 mW of power without buffers, and its core part occupies only 0.048 mm 2 of IC area.
2022 52nd European Microwave Conference (EuMC), Milan, Italy, 2022, pp. 688-691, doi: 10.23919/EuMC54642.2022.9924349.
Dmitrii Kruglov, Oleg Iupikov, Marianna Ivashina, Rob Maaskant, “Enhancing Mmwave on-Chip-Antennas Using in-Package Electromagnetic Bandgap Structures”
Abstract: We propose a silicon on-Chip-in-Package antenna design featuring a simulated radiation efficiency of > 70% and an S11 matching better than −10 dB in the 112–125 GHz frequency range. High radiation performance is achieved by: (i) thinning the silicon substrate down to 100 μm through wafer-level grinding; (ii) embedding the IC in-between two PCBs, one of which forms an electromagnetic bandgap structure that attenuates the EM leakage inside the silicon substrate. Furthermore, since the die-embedding concept employs the gap-waveguide packaging technology, a universal contactless waveguide interconnect is realized between the IC and the radiating gap waveguide in the package. This will also enable modular antenna designs.
2021 51st European Microwave Conference (EuMC), London, United Kingdom, 2022, pp. 885-888, doi: 10.23919/EuMC50147.2022.9784298.
Elmine Meyer, Cornelis Vertegaal, Leanne Johnson, Petrie Meyer, Ulf Johannsen, “Substrate Integrated Waveguide Pedestal Filtenna for Sub-6 GHz 5G Radio Frequency Front-Ends”
Abstract: This paper presents the design, manufacturing, and measurement of a novel substrate integrated waveguide (SIW) pedestal filtering antenna solution for use in 5G New Radio sub-6 GHz communications. Miniaturization is achieved through the use of SIW pedestal resonators and integration of the radiating element into the filter design, resulting in higher order suppression. The design generates a third order filtering response utilizing SIW pedestal resonators and a patch antenna element. The manufactured SIW pedestal filtenna achieves a 10 dB return loss bandwidth of 4.29 % about a centre frequency of 3.63 GHz, and a boresight gain of 3.66 dBi. Additionally a 1×4 linear array is measured, demonstrating the applicability to 5G radio frequency front-ends.
2022 16th European Conference on Antennas and Propagation (EuCAP), 2022, pp. 1-5, doi: 10.23919/EuCAP53622.2022.9769565.
Kirill Alekseev, Marcus Hasselblad, Klas Eriksson, Martin Johansson, Bart Smolders, Ulf Johannsen, “Low-Noise Amplifier-Antenna Co-Design Overview”
Abstract: Antenna and low-noise amplifier (LNA) co-design is a promising method for increasing the sensitivity of millimeter-wave (mmWave) receiver systems. Co-design involves several individual steps which usually do not intersect with each other in one design flow, but this method combines all of them together and allows to obtain mutual benefits for all components. This paper gives an overview of several different mmWave engineering tasks like antennas and monolithic microwave integrated circuit (MMIC) design together with RF interconnection solutions like wirebonding, flip-chip and packaging technology. The suggestion of the mmWave receiver co-design for achieving minimum noise figure at low costs is also provided.
2022 16th European Conference on Antennas and Propagation (EuCAP), 2022, pp. 1-5, doi: 10.23919/EuCAP53622.2022.9769473.
Artem R. Vilenskiy, Yingqi Zhang, Marianna V. Ivashina, “Methods for Attenuating and Terminating Waves in Ridge Gap Waveguide at W-Band: Carbon-Loaded Foam, Carbonyl Iron Paint, and Nickel Plating”
Abstract: Several methods for electromagnetic waves matched termination and attenuation in a ridge gap waveguide (RGW) are experimentally investigated at W-band. At these frequencies, the implementation of matched loads and attenuators is especially complicated due to small sizes of RGW design features that limits application of traditional waveguide absorbing structures (e.g., absorbing sheets and finlines, ferrite insets, carbonyl iron walls, etc.). The following three techniques are considered: (i) filling an RGW gap with a carbon-loaded foam; (ii) covering a ridge (and pins) with a carbonyl iron paint; (iii) selective nickel plating of an RGW line segment. It was found that the first method exhibits a great broadband absorbing performance and can be easily implemented in a lab environment, whereas the second method can realize a more accurate and predictable attenuating performance. Finally, nickel plating allows for designing resonant RGW terminations and is more interesting from the industrial perspective.
2021 51st European Microwave Conference (EuMC), 2022, pp. 217-220, doi: 10.23919/EuMC50147.2022.9784367.
Artem R. Vilenskiy, Yingqi Zhang, Esme Galesloot, Adrianus Bart Smolders, Marianna V. Ivashina, “Millimeter-Wave Quasi-Optical Feeds for Linear Array Antennas in Gap Waveguide Technology”
Abstract: A realization of the quasi-optical (QO) feed concept for linear millimeter-wave (sub-)array antennas is demonstrated in gap waveguide technology. The proposed feed architecture employs an input transition from a ridge gap waveguide (RGW) to a groove gap waveguide (GGW), a radial (H-plane sectoral) GGW section, and a transition to an output RGW array. A design decomposition approach is presented to reduce simulation complexity. Several 20-element QO feed implementations are investigated at W-band demonstrating a 20% relative bandwidth (85-105 GHz), 0.5 dB insertion loss, and a capability of an amplitude taper control within the 10-20 dB range.
2022 16th European Conference on Antennas and Propagation (EuCAP), 2022, pp. 1-5, doi: 10.23919/EuCAP53622.2022.9769175.
Moïse Safari Mugisho, Saikat Kumar Maity, Christian Friesicke, Rüdiger Quay, “Harmonic-Injection Doherty Power Amplifiers with a High Small-Signal Gain”
Abstract: This paper presents a novel Doherty power amplifier (DPA) in which a second harmonic (2f 0 ) current is injected into the drain of the auxiliary device. Hence, the name harmonic-injection Doherty power amplifier (HI-DPA). The performance parameters of the HI-DPA are analytically derived and show that the injection of a 2f 0 current into the drain of the auxiliary device reduces the maximum current required from the auxiliary PA. Consequently, the portion of input power allocated to the auxiliary PA reduces, resulting in a significant improvement in small-signal gain (SSG) and power-added efficiency (PAE) compared to the conventional DPA. The analytical results are validated through the design and simulation of two GaN HEMTs single-stage HI-DPAs exhibiting a SSG of 9.5 and 13.6 dB at 3.6 GHz while maintaining a high PAE at peak and 6 dB back-off power.
2022 International Workshop on Integrated Nonlinear Microwave and Millimetre-Wave Circuits (INMMiC), 2022, pp. 1-3, doi: 10.1109/INMMiC54248.2022.9762221.
Christian Fager, Simon Rimbom, Emma Rådahl, Husileng Bao, and Thomas Eriksson, “Comparison of Co-located and Distributed MIMO for Indoor Wireless Communication”
Abstract: This paper compares the communication performance for co-located and emerging distributed MIMO in a typical indoor scenario. The simulations, which are verified against experimental measurement data, show that distributed MIMO offers a significantly more uniform capacity for the users. The results also show that the same user capacity can be achieved with half the number of antennas in the distributed MIMO case.
2022 IEEE Radio and Wireless Symposium (RWS), 2022, pp. 83-85, doi:10.1109/RWS53089.2022.9719879.
Mehrangiz Ensan, Hamdi Joudeh, Alex Alvarado, Ulf Gustavsson, Frans M. J. Willems, “On Cloud Radio Access Networks With Cascade Oblivious Relaying”
Abstract: We consider a discrete memoryless cloud radio access network in which K users communicate with a remote destination through 2 relays in a cascade. The relays are oblivious in the sense that they operate without knowledge of the users’ codebooks. We focus on a scenario where the first and second relays are connected through a finite-capacity error-free link, while the second relay is connected to the remote destination via an infinite-capacity link. We establish the capacity region in this case, and show that it is achieved via a compress-and-forward scheme with successive decoding. Finally, the extension to Gaussian networks is discussed.
2021 IEEE Information Theory Workshop (ITW), 2021, pp. 1-6, doi:10.1109/ITW48936.2021.9611433.
Dmitrii Kruglov, Oleg Lupikov, Marianna Ivashina, Rob Maaskant, “Enhancing mmwave on-Chip-Antennas Using in-Package Electromagnetic Bandgap Structures”
Abstract: We propose a silicon on-Chip-in-Package antenna design featuring a simulated radiation efficiency of > 70% and an S11 matching better than −10 dB in the 112–125 GHz frequency range. High radiation performance is achieved by: (i) thinning the silicon substrate down to 100 μm through wafer-level grinding; (ii) embedding the IC in-between two PCBs, one of which forms an electromagnetic bandgap structure that attenuates the EM leakage inside the silicon substrate. Furthermore, since the die-embedding concept employs the gap-waveguide packaging technology, a universal contactless waveguide interconnect is realized between the IC and the radiating gap waveguide in the package. This will also enable modular antenna designs.
2021 51st European Microwave Conference (EuMC), 2022, pp. 885-888, doi: 10.23919/EuMC50147.2022.9784298.
H. Bao, I. C. Sezgin, Z. S. He, T. Eriksson and C. Fager, “Automatic Distributed MIMO Testbed for Beyond 5G Communication Experiments”
Abstract: This paper demonstrates an automated testbed suitable for beyond-5G distributed MIMO experiments, where bandwidth, number of transmitters and precoding methods are flexible and configured through a central unit. This is based on an all-digital radio-over-fiber approach to communication through 12 fully coherent, low-complexity remote radio transmitters. An automated robot receiver is implemented to facilitate efficient communication data collection in realistic environments. Using the proposed system, co-located and distributed MIMO communication antenna configurations are compared in a real in-door environment. The results show that distributed MIMO provides more significantly more uniform power distribution and better overall MIMO capacity compared to co-located MIMO.
2021 IEEE MTT-S International Microwave Symposium (IMS), 2021, pp. 697-700, doi: 10.1109/IMS19712.2021.9574865.
R. Argaez-Ramirez, J. -R. Perez-Cisneros and C. Fager, “Investigation of power amplifier performance under load mismatch conditions”
Abstract: The time-varying loading conditions that power amplifiers (PAs) experience in active antenna systems degrade their overall performance. Consequently, the design of linear and highly-efficient PAs under mismatch is more important than ever. In this paper, different common and promising PA architectures, i.e. class-B, balanced, Doherty (DPA) and load-modulated-power-amplifier (LMBA), are analyzed under mismatch. Their sensitivity in terms of linearity, efficiency and output power is compared under a LTE signal excitation. Average drain efficiency (DE), average output power, normalized-mean-square-error (NMSE) as well as maximum output power variations are presented for each architecture as function of the voltage-standing-wave ratio (VSWR). Thereby, the most suitable PA architecture to be integrated in active antenna systems may be identified.
2021 IEEE Topical Conference on RF/Microwave Power Amplifiers for Radio and Wireless Applications (PAWR), 2021, pp. 41-43, doi: 10.1109/PAWR51852.2021.9375507.
D. Kruglov, M. Ivashina, O. Iupikov and R. Maaskant, “Numerical analysis of Huygens-like on-chip antennas for mm-wave applications”
Abstract: As we transition to 5G and beyond, the frequencies increase and the efficiency of the antennas becomes a pressing issue. Silicon technologies are preferred when it comes to en masse user equipment production, but the antennas in silicon suffer from high dielectric losses and strong substrate waves coupling. The use of a Huygens source as the antenna element has a potential of decreasing these negative effects, as was demonstrated in several non-silicon PCB designs. In this paper, we investigate if a similar performance enhancement can be achieved in thin back-gated silicon antenna chips. We present a numerical comparison of an electric dipole, a magnetic dipole and a Huygens source antenna at 120 GHz on a lossy silicon substrate sitting on a ground plane. Antennas are defined in MATLAB as distributed currents and imported as near-field sources into CST Microwave Studio. This way we treat the problem in a very general way without regards for any particular physical antenna implementations. Radiation efficiency and gain are shown as functions of substrate thickness. We found that there is no apparent advantage of using a Huygens source over either electric or a magnetic dipole in the described setup. We argue that this result is based on the fact that the Huygens source is derived assuming infinite current sheets at the interface of two infinite homogeneous regions, and propose another definition for a Huygens source in multi-layer structures.
2021 15th European Conference on Antennas and Propagation (EuCAP), 2021, pp. 1-5, doi: 10.23919/EuCAP51087.2021.9411489.
A. R. Vilenskiy, E. Galesloot, Y. Zhang, A. Bart Smolders and M. V. Ivashina, “Quasi-Optical Beamforming Network for Millimeter-Wave Electronically Scanned Array Antennas with 1-Bit Phase Resolution”
Abstract: State-of-the-art design solutions for electronically scanned array antennas are mostly limited to microwave to low mm-wave frequency bands, while the demand for new designs at higher frequencies (i.e. frequencies beyond 100 GHz) is rapidly growing. We attempt to fill in this knowledge gap by presenting a new linear array antenna architecture as a building block of 2D arrays that can enable efficient beam steering and a simplified array design. This concept is based on the combination of a low-loss quasi-optical (QO) feed, providing predefined antenna port excitation, with 1-bit phase shifters which are co-integrated with the array antenna elements. In this study, we formulate the array design problem as minimization of the sidelobe level (SLL) through an optimum quasi-randomization of phase errors. An analytical expression for the optimum focal ratio of the QO feed has been derived to establish the relationships between the key design parameters. These results are validated through numerical simulations revealing that the optimum focal ratio leads to the minimum SLL.
2021 15th European Conference on Antennas and Propagation (EuCAP), 2021, pp. 1-5, doi: 10.23919/EuCAP51087.2021.9410922.
Y. Zhang, A. R. Vilenskiy and M. V. Ivashina, “W-band Waveguide Antenna Elements for Wideband and Wide-Scan Array Antenna Applications For Beyond 5G”
Abstract: Energy-efficient and highly-compact beam-steering array antennas at W- and D-band frequencies are considered as future enabling technologies for beyond-5G applications. However, most existing solutions at these frequencies are limited to the fixed-beam and frequency-dependent beam-steering scenarios. This paper aims to fill in this knowledge gap by investigating various types of antenna elements as potential candidates for wideband and wide-scan arrays at W-band. We consider open-ended ridge and ridge gap waveguide radiating elements that could overcome the physical complexities associated with the integration of elements in large-scale electronically scanned arrays. An infinite array approach is used, where we have adopted a triangular array grid and introduced E- and H-plane grooves to the element design to enhance the scan and bandwidth performance. Cross-comparison of several simulated array designs leads to the final array elements with 25% impedance bandwidth over the scan range of ±40° in both the E- and H-planes.
2021 15th European Conference on Antennas and Propagation (EuCAP), 2021, pp. 1-5, doi: 10.23919/EuCAP51087.2021.9411184.