Search

This paper presents a novel wideband single-pole-single-thru (SPST) switch fabricated by silicon micromachining and operates based on short-circuiting the dominant mode of the rectangular waveguide. The switch has a compact footprint, with a total size of 2×3.5×1.2 mm. The switching mechanism is implemented by a microelectromechanical (MEMS) actuator with an actuation voltage of ~40 V. It has two operating states of propagating and blocking mode. The measured return loss and insertion loss of the switch are 17 dB and 0.7-1.1 dB at 220-290 GHz in the propagating state. The presented switch also has tuning capability to operate with 20 dB return loss at 220-266 GHz. The measured isolation is also 28.5-32.5 dB in the blocking state at the same frequency span. QC 20230619

In this paper, an H-band radar system is built, and measurement of in-cabin object detection and passenger monitoring is demonstrated to better understand the in-cabin propagation environment at sub-THz frequencies. QC 20230531

This paper describes a silicon micromachined radar frontend. The designed frontend system includes active and passive elements within a single silicon chip due to the high integration capability of silicon micromachining techniques. The active part includes a switching circuit, and the passive part consists of a beam steering and beam shaping network and a 2×8 array antenna. The frontend has two WR-3.4 standard waveguide ports, and each port can create two frequency steerable radiation patterns controlled by the switching circuit. The return loss of both ports is better than 10 dB at 220-267 GHz for both beam shapes. The size of the whole system is 14.3×20×1.2 mm, and it can be used in imaging, tracking, and surveillance applications. QC 20230612

This paper presents a silicon micromachined reconfigurable beam-steering frontend chip in which multiple components are integrated within a single silicon chip. The size o the whole frontend chip is 14.3×20×1.2 mm3. The signal path includes a novel switching circuit, a beam-steering network, two power-dividing networks, and a 2×8 array antenna. The presented frontend chip is able to create two frequency steerable beam-shapes. The switching circuit determines which beam shape to be radiated. The first beam-shape is a steerable broad fan-beam with reduced sidelobe level (SLL) in the H-plane, and the second is a steerable notched fan-beam. The measured SLL of the broad beam is better than 18.5 dB in the H-plane, and the measured notch depth is better than 24 dB in the E-plane pattern. Both radiation patterns can be steered by frequency and move from -20 degrees at 238 GHz to +20 degrees at 248 GHz.The measured return loss of the fabricated device is better than 15 dB at 220-265 GHz, which is equal to almost 18.6 % fractional bandwidth. QC 20230630

This paper presents a novel single-pole-single-throw wideband microelectromechanical switch circuit operating in the 220 to 290 GHz frequency band. The switching operation is based on short-circuiting the dominant TE10 mode of the rectangular waveguide by micro-electromechanically reconfigurable surfaces. The improved performance of this switch circuit comes from utilizing two such reconfigurable surfaces and taking advantage of the interference between them to achieve improved RF performance, in particular in terms of return loss and isolation. The switch has a compact design with dimensions of 2×3.5×1.2 mm3. Due to its axial port arrangement, it can be mounted directly between two standard waveguide flanges. The insertion loss, measured between the two standard waveguide flange interfaces and including all internal circuit routing and E-plane bends, is between 0.7-1.2 dB. The measured return loss is better than 17 dB in the entire frequency band of 220 to 290 GHz. Reference waveguide measurements of the same prototype fabrication run showed that 0.2-0.5 dB of the measured insertion loss comes from the waveguide itself. The measured isolation of the switch is very uniform in the whole 220-290 GHz waveguide band and between 28.5-32.5 dB. The measured fractional bandwidth of 27.5% has been achieved, which is almost equal to a full waveguide band performance. QC 20230612

QC 20230615

This paper investigates a novel radar concept that is based on a minimalistic, small-aperture antenna array but features intelligent beam-shape switching and artificial-intelligence signal processing. In contrast to conventional phased-arrays, size, cost, and hardware complexity are drastically reduced by the proposed dual-antenna array which can create a broad and a frequency-scanning notched beam shape. The angular-resolution and target discrimination performance of the proposed radar concept have been validated by radar simulations for single and multiple target scenarios. For the signal processing, two convolutional neural networks (CNN) and a multilayer perceptron model are benchmarked against each other. A further CNN is implemented for estimating the number of targets, which can be used to pre-select the type of network determining range and cross-range of multiple targets. This paper shows that a small antenna aperture frontend in combination with beam-shape switching and artificial-intelligence signal processing methods is a suitable hardware-efficient radar concept for accurate multi-target location.

Current THz systems are predominantly manufactured by CNC milling. Despite the high level of precision which CNC milling achieved in recent years, this fabrication method lacks volume manufacturability and is inferior in performance to silicon micromachining, which achieves feature sizes and fabrication reproducibility down to micrometers, surface roughness down to nanometers (for extremely low loss), and high-aspect ratio geometries which are impossible to fabricate in any other fabrication technology. Micromachined micromechanical devices, for instance mobile-phone microphones and inertial sensors, are already for many years manufactured to billions of devices per year at very low cost. This webinar gives an overview of state of the art, the capabilities and limitations of silicon micromachining for millimeter and submillimeter-wave frequencies, and gives several examples of recent achievements of very high performance silicon-micromachined waveguide based THz devices and systems, including: a low-loss waveguide technology with 0.02 dB/mm at 330 GHz, with integrated components such as low-loss couplers, power splitters, matched loads; micromachined high-Q filter examples based on cavity resonators with measured Q-factors of 1600 at 150 GHz and 900 at 700 GHz, enabling the first 1% fractional bandwidth filters at submillimeter-wave frequencies; a silicon-micromachined platform for a point-to-point telecommunication link including a 130-148 GHz antenna diplexer with 1.5 dB insertion loss and 60 dB isolation, and waveguide-integrated SiGe MMICs; very complex, multi-level waveguide devices including a orthomode transducer from 220-330 GHz with less than 0.6 dB insertion loss and cross-polarization of 35-70 dB in this waveguide band; a corporate-fed antenna array with 256 elements at 320 to 400 GHz, with only 0.8 dB insertion loss, achieving 34 dBi gain; a 1024 antenna array at 320-400 GHz with 38 dBi gain and 1.5 dB insertion loss; a frequency-steering micromachined radar frontend at 220-300 GHz, achieving a 55 degree field of view with a 3.5 to 10 degree HPBW, using an integrated 2.5D quasi-optical reflector and a leaky-wave antenna array, all of the size and thickness of a thumb nail; MEMS-waveguide switches operating at 140-220 GHz with 0.6 dB insertion loss and 50 dB isolation over the whole band, and even a 500-750 GHz switch with 2.5 dB insertion loss and 18 dB isolation; and a 2.5-dB insertion loss 360 degree phase shifter for the 220-330 GHz band with less than 4 degree phase error for all states over the whole bandwidth. Major applications presented are radar (in particular next-generation car radars), telecommunication and space-borne radiometers.

This work proposes a novel unbalanced corporate-feed network antenna design with amplitude tapering of the radiated power to get a reduced sidelobe level. The phase imbalance of the asymmetric power dividers is compensated by integrated delay lines which maintain the aperture efficiency. The 10 dB beamwidth is reduced by 8.5% in E-plane and 10.2% in H-plane after the phase compensation. A 𝟏𝟔×𝟏𝟔 and a 𝟑𝟐×𝟑𝟐 array antenna have been designed for 230-290 GHz, i.e., a 23% fractional bandwidth. The 𝟏𝟔×𝟏𝟔 and 𝟑𝟐×𝟑𝟐 antenna's realized gain is between 29.4-32.1 dBi and 34.6-37.6 dBi, with sidelobe levels better than 21.2 dB and 20.5 dB, respectively. The design is optimized for being implemented by silicon micromachining. To the best of the author's knowledge, this is the first amplitude tapered corporate feed slot array antenna with delay lines for phase compensation that has been proposed in this frequency range with this wide operational bandwidth. Part of proceedings: ISBN 978-88-31299-04-6QC 20220612 CAR2TERA

Funding Information: Funding: The work was supported by the European Union’s Horizon 2020 FET Open project TERAmeasure (grant agreement No 862788), by the “International Research Agendas” program of the Foundation for Polish Science co-financed by the European Union under the European Regional Development Fund (No. MAB/2018/9), by the statutory sources of the Department of Structural Materials, Military University of Technology (project no. UGB 22–846/2021/WAT) and by the Ministry of Science and Higher Education of the Russian Federation (project no. FSRR-2020-0004), (Igor S. Nefedov). A. Krajewska was supported by the Foundation for Polish Science (FNP). Publisher Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. Thin layers of silver nanowires are commonly studied for transparent electronics. However, reports of their terahertz (THz) properties are scarce. Here, we present the electrical and optical properties of thin silver nanowire layers with increasing densities at THz frequencies. We demonstrate that the absorbance, transmittance and reflectance of the metal nanowire layers in the frequency range of 0.2 THz to 1.3 THz is non-monotonic and depends on the nanowire dimensions and filling factor. We also present and validate a theoretical approach describing well the experimental results and allowing the fitting of the THz response of the nanowire layers by a Drude–Smith model of conductivity. Our results pave the way toward the application of silver nanowires as a prospective material for transparent and conductive coatings, and printable antennas operating in the terahertz range—significant for future wireless communication devices.