| 1. |
- Töpfer, Fritzi, 1985-
(author)
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Micromachined Microwave Sensors for Non-Invasive Skin Cancer Diagnostics
- 2019
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Doctoral thesis (other academic/artistic)abstract
- Malignant melanoma is one of the cancers with the highest incident rates. It is also the most dangerous skin cancer type and an early diagnosis is crucial for the successful treatment of malignant melanoma patients. If it is diagnosed and treated at an early stage, the survival rate for patients is 99%, however, this is reduced to only 25% if diagnosed at a later stage. The work in this thesis combines microsystem technology, microwave engineering and biomedical engineering to develop a sensing tool for early-stage malignant melanoma diagnostics. Such a tool could not only increase the clinical accuracy of malignant melanoma diagnosis, but also reduce the time needed for examination, and lower the number of unnecessary biopsies. Furthermore, a reliable and easy-to-use tool can enable non-specialist healthcare personnel, including primary care physicians or nurses, to perform a prescreening for malignant melanoma with a high sensitivity. Consequently, a large number of patients could receive a timely examination despite the shortage of dermatologists, which exists in many healthcare systems. The dielectric properties of tumor tissue differ from healthy tissue, which is mainly accounted to a difference in the water content. This difference can be measured by a microwave-based sensing technique called microwave reflectometry. Previously reported microwave-based skin measurements largely relied on standard open-ended waveguide probes that are not suitable for early-stage skin tumor diagnosis. Thus, alternative near-field probe designs based on micromachined dielectric-rod waveguides are presented here. The thesis focuses on a broadband microwave probe that operates in the W-band (75 to 110 GHz), with a sensing depth and resolution tailored to small and shallow skin tumors, allowing a high sensitivity to early-stage malignant melanoma. Prototypes of the probe were fabricated by micromachining and characterized. For the characterization, a novel type of silicon-based heterogeneous sample with tailor-made permittivity was introduced. Furthermore, the performance of the probe was evaluated in vivo. First, through measurements on human volunteers, it was shown that the probe is sensitive to artificially induced changes of the skin hydration. Then, measurements on murine skin melanoma models were performed and small early-stage skin tumors were successfully distinguished from healthy skin. Additionally, a resonant probe for microwave skin sensing was designed and micromachined protoypes were tested on phantom materials. However, the resonant probe was found less suitable than the broadband probe for the measurements on skin. The broadband probe presented in this thesis is the first microwave nearfield probe specifically designed for early-stage malignant melanoma diagnostics and successfully evaluated in vivo.
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| 2. |
- Beuerle, Bernhard, 1983-
(author)
-
Silicon micromachined waveguide components for terahertz systems
- 2020
-
Doctoral thesis (other academic/artistic)abstract
- This thesis presents silicon micromachined waveguide components for sub-terahertz and terahertz (THz) systems fabricated by deep reactive ion etching (DRIE). Historically the main driving force for the development of THz systems has been space-based scientific instruments for astrophysics, planetary and Earth science missions. Recent advances in active and passive components for the THz frequency range increased its usage in areas such as imaging, security, communications and biological instrumentation. Traditionally the primary technology for components and interconnections approaching THz frequencies has been hollow metal waveguides fabricated by computer numerical controlled (CNC) milling. Systems using this technology are bulky and hand-assembled, getting more expensive and complicated with an increasing complexity of the system. In recent years silicon micromachining has emerged as a viable alternative for THz components and integrated systems promising more compact integrated systems.The thesis reports on a new low-loss silicon micromachined waveguide technology using silion-on-insulator (SOI) wafers. Several low-loss waveguide components in the frequency range of 220–330 GHz have been fabricated and characterized, such as hybrid couplers, splitters and matched loads. Furthermore, an investigation of fabrication accuracy and repeatability for high-Q filters in the sub-THz frequency range using the same waveguide technology is presented.For on-wafer waveguide characterization a novel CPW probe to micromachined waveguide transition concept is introduced. The transition is co-fabricated together with the devices under test in the same waveguide technology using SOI technology. It consists of a CPW probing interface and a pin protruding into the waveguide cavity acting as an E-field probe to excite the dominant mode of the rectangular waveguide. Designed and characterized for the frequency range of 220–330 GHz, the transition was successfully used for on-wafer characterization of the waveguide components previously presented. The scalability of the concept to higher frequencies is shown by presenting a modified transition capable of device characterization up to 500 GHz.The integration of monolithic micromachined integrated circuits (MMICs) with silicon micromachined waveguides is investigated, with a focus on scalability to higher frequencies and their compatibility with industrial assembly tools. A new integration concept for THz systems is presented and a back-to-back transition structure for the integration of SiGe MMICs with silicon micromachined waveguides at D-band frequencies (110–170 GHz) has been characterized. Furthermore, a co-designed transition from InP MMIC to silicon micromachined rectangular waveguide is presented, consisting of a compact microstrip to waveguide transition and a vertical waveguide to in-plane waveguide bend in the silicon micromachined waveguide technology. The concept has been fabricated and characterized in a back-to-back configuration for the frequency range of 220–330 GHz.
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| 3. |
- Campion, James, 1989-
(author)
-
Exploiting the Terahertz Spectrum with Silicon Micromachining : Waveguide Components, Systems and Metrology
- 2021
-
Doctoral thesis (other academic/artistic)abstract
- The terahertz spectrum (300 GHz - 3 THz) represents the final frontier for modern electronic and optical systems, wherein few low-cost, volume-manufacturable solutions exist. THz frequencies are of great scientific and commercial interest, with applications as diverse as radio astronomy, sensing and imaging and wireless communications. Current THz technology is restricted by its expense, form-factor and performance limitations. Future exploitation of this spectrum requires the development of new technologies which support its use in high-volume applications. Any such technology must offer excellent mechanical and electrical performance and be compatible with industrial grade tools and processes. In response to this, this thesis presents the development of silicon micromachined waveguide components and systems for THz and sub-THz frequencies. Silicon micromachining offers a unique combination of small feature sizes and low surface roughness and manufacturing tolerances in a scalable process.At the core of this work lies a new silicon-on-insulator (SOI) waveguide technology which minimises surface roughness to provide low insertion loss. Waveguide filters and diplexers between 100–500 GHz are implemented using this technology, each with state-of-the-art performance. A new platform for waveguide systems is developed to enable fully micromachined systems to be realised. In contrast to previous solutions, this platform integrates of all DC, intermediate and radio frequency signals in a single medium. Two unique non-galvanic transitions provide interfaces to active components and metallic waveguides. Semi-automated industrial tools perform system assembly with high accuracy and are used to implement complete transceivers for wireless communication at 110–170 GHz. Commercial-grade silicon germanium integrated circuits are used for all active components. This represents the first step in the adoption of this new technology in an industrial scenario.Large-scale use of the THz spectrum necessitates a shift from discrete components to complete integrated systems, in a similar matter to that seen in digital electronics and will require accurate, high-throughput characterisation and verification infrastructures. To support this, two transitions from co-planar waveguide probes to rectangular waveguide are proposed to allow for device characterisation in an on-wafer environment from 220–500 GHz. The accuracy and precision of the SOI micromachining process, coupled with the mechanical properties of silicon, make it highly suited to the creation of precision metrology standards. By harnessing these properties, a new class of micromachined waveguide calibration standards is developed, the peformance of which exceeds current solutions. Traceability of the standards is documented through detailed mechanical, electrical and statistcal analysis of fabricated samples.This work presented in thesis enables the development of THz components and systems, and methods to test them, in an established, high-volume technology, enabling their use in a wide range of applications.
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| 4. |
- Frid, Henrik
(author)
-
On millimeter and submillimeter wave focal plane arrays implemented with MEMS waveguide switches
- 2017
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Licentiate thesis (other academic/artistic)abstract
- This thesis presents research towards enabling micromachined millimeter and submillimeter wave focal plane arrays (FPAs). The FPAs operate under the following principle: a switch network consisting of microelectromechanical (MEMS) switches, integrated with micromachined waveguides, is used to feed an array of antenna elements, located in the focal plane of a high-gain quasi-optical system. Hence, it is possible to switch between a set of narrow beams in different directions. Such beam steering systems are needed for future millimeter and submillimeter wave imaging and communication systems. The contributions to future MEMS-switchable FPAs presented here are organized in three papers, as described below.Paper I presents a criterion on the spacing between adjacent FPA elements which results in -3 dB overlap between the switched beams, for the special case when an extended hemispherical dielectric lens is used as the optical system. A key step towards this criterion is a closed-form relation between the scan angle and the FPA element's position, which results in an expression for the effective focal length of extended hemispherical lenses. A comparison with full-wave simulations demonstrates an excellent agreement with the presented theoretical results. Finally, it is shown that the maximum feasible FPA spacing when using an extended hemispherical lens is about 0.7 wavelengths.Paper II presents a numerical study of silicon-micromachined planar extended hemispherical lenses, with up to three matching regions used to reduce internal reflections. The effective permittivity of the matching regions is tailor-made by etching periodic holes in the silicon wafer. The optimal thickness and permittivity of the matching regions were determined using TRF optimization, in order to yield the maximum wide-band aperture efficiency and small side-lobes. We introduce a new matching region geometry, referred to as shifted-type matching regions, and it is demonstrated that using three shifted-type matching regions results in twice as large aperture efficiency as compared to using three conventional concentric-type matching regions.Paper III presents a submillimeter-wave single-pole single-throw (SPST) 500-750 GHz MEMS waveguide switch, based on a MEMS-reconfigurable surface inserted between two waveguide flanges. A detailed design parameter study is carried out to select the best combination of the number of horizontal bars and vertical columns of the MEMS-reconfigurable surface, for achieving a low insertion loss in the transmissive state and a high isolation in the blocking state. A method is presented to model the non-ideal electrical contacts between the vertical cantilevers of the MEMS surface, with an excellent agreement between the simulated and measured isolation. It is shown that the isolation can be improved by replacing an ohmic contact by a new, capacitive contact. The measured isolation of the switch prototype is better than 19 dB and the measured insertion loss is between 2.5 and 3 dB.
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| 5. |
- Shah, Umer
(author)
-
Novel RF MEMS Devices Enabled by Three-Dimensional Micromachining
- 2014
-
Doctoral thesis (other academic/artistic)abstract
- This thesis presents novel radio frequency microelectromechanical (RF MEMS) circuits based on the three-dimensional (3-D) micromachined coplanar transmission lines whose geometry is re-configured by integrated microelectromechanical actuators. Two types of novel RF MEMS devices are proposed. The first is a concept of MEMS capacitors tuneable in multiple discrete and well-defined steps, implemented by in-plane moving of the ground side-walls of a 3-D micromachined coplanar waveguide transmission line. The MEMS actuators are completely embedded in the ground layer of the transmission line, and fabricated using a single-mask silicon-on-insulator (SOI) RF MEMS fabrication process. The resulting device achieves low insertion loss, a very high quality factor, high reliability, high linearity and high self actuation robustness. The second type introduces two novel concepts of area efficient, ultra-wideband, MEMS-reconfigurable coupled line directional couplers, whose coupling is tuned by mechanically changing the geometry of 3-D micromachined coupled transmission lines, utilizing integrated MEMS electrostatic actuators. The coupling is achieved by tuning both the ground and the signal line coupling, obtaining a large tuneable coupling ratio while maintaining an excellent impedance match, along with high isolation and a very high directivity over a very large bandwidth. This thesis also presents for the first time on RF nonlinearity analysis of complex multi-device RF MEMS circuits. Closed-form analytical formulas for the IIP3 of MEMS multi-device circuit concepts are derived. A nonlinearity analysis, based on these formulas and on measured device parameters, is performed for different circuit concepts and compared to the simulation results of multi-device conlinear electromechanical circuit models. The degradation of the overall circuit nonlinearity with increasing number of device stages is investigated. Design rules are presented so that the mechanical parameters and thus the IIP3 of the individual device stages can be optimized to achieve a highest overall IIP3 for the whole circuit.The thesis further investigates un-patterned ferromagnetic NiFe/AlN multilayer composites used as advanced magnetic core materials for on-chip inductances. The approach used is to increase the thickness of the ferromagnetic material without increasing its conductivity, by using multilayer NiFe and AlN sandwich structure. This suppresses the induced currents very effectively and at the same time increases the ferromagnetic resonance, which is by a factor of 7.1 higher than for homogeneous NiFe layers of same thickness. The so far highest permeability values above 1 GHz for on-chip integrated un-patterned NiFe layers were achieved.
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| 6. |
- Smirnov, Serguei
(author)
-
Tunable Nanomaterials and their Applications for Terahertz Devices : Carbon Nanotubes and Silver Nanowires
- 2021
-
Doctoral thesis (other academic/artistic)abstract
- The interest in terahertz (THz) technologies is growing in academia and industry. The design of electronic components at THz frequencies is relevant to application areas such as telecommunication, radar, material spectroscopy, and medical imaging and diagnosis. Even though high-performance THz instrumentation becomes more available, the systems are not commonly found outside of the laboratory environment. Researchers have recently demonstrated a platform based on dielectric rod waveguides (DRWs) that is suitable for integrating THz electronics. The electromagnetic waves propagate inside a low-loss dielectric structure, a concept similar to optical fibres. DRWs have seen many advances for THz electronics in recent years. However, the platform still lacks essential active and passive components for building complete systems. This thesis investigates ways to integrate tunable nanomaterials to dielectric waveguides in order to design novel terahertz devices. First, silicon rectangular DRWs are investigated at 75 GHz to 500 GHz frequencies. In particular, the interface with the measurement instrumentation and the tapered transitions to hollow metallic waveguides are considered by electromagnetic simulations. Additionally, ways to implement phase shifters and attenuators are explored using thin layers of nanomaterials that are modelled by an impedance surface in the simulations. Second, several nanomaterials are studied by optical spectrophotometry, Raman spectroscopy, and terahertz time-domain and frequency- domain spectroscopy. Thin layers of silver nanowires are fabricated with increasing densities, ranging from individual nanowires to nanowire networks at the percolation threshold, to thick semi-continuous layers. This technique allows the manufacturing of optically transparent samples with a tunable THz conductivity. Additionally, thin layers of single-walled carbon nanotubes are investigated. Their dielectric properties are shown to be tunable by light illumination, supported by measurements at low frequencies and in the terahertz range. Finally, tunable THz devices based on dielectric waveguides are designed, manufactured, and characterized. Thin layers of carbon nanotubes are integrated with DRWs and used as a surface impedance to modify the wave propagation in the waveguide. The presented phase shifters are tunable by light with wideband operation at sub-THz and potentially higher frequencies, and further device improvements are proposed.
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| 7. |
- Somjit, Nutapong
(author)
-
Novel RF MEMS Devices for W-Band Beam-Steering Front-Ends
- 2012
-
Doctoral thesis (other academic/artistic)abstract
- This thesis presents novel millimeter-wave microelectromechanical-systems (MEMS) components for W-band reconfigurable beam-steering front-ends. The proposed MEMS components are novel monocrystalline-silicon dielectric-block phase shifters, and substrate-integrated three-dimensional (3D) micromachined helical antennas designed for the nominal frequency of 75 GHz. The novel monocrystalline-silicon dielectric-block phase shifters are comprised of multi-stages of a tailor-made monocrystalline-silicon block suspended on top of a 3D micromachined coplanar-waveguide transmission line. The relative phase-shift is obtained by vertically pulling the suspended monocrystalline-silicon block down with an electrostatic actuator, resulting in a phase difference between the up and downstate of the silicon block. The phase-shifter prototypes were successfully implemented on a high-resistivity silicon substrate using standard cleanroom fabrication processes. The RF and non-linearity measurements indicate that this novel phase-shifter design has an excellent figure of merit that offers the best RF performance reported to date in terms of loss/bit at the nominal frequency, and maximum return and insertion loss over the whole W-band, as compared to other state-of-the-art MEMS phase shifters. Moreover, this novel design offers high power handling capability and superior mechanical stability compared to the conventional MEMS phase-shifter designs, since no thin moving metallic membranes are employed in the MEMS structures. This feature allows MEMS phase-shifter technology to be utilized in high-power applications. Furthermore, the return loss of the dielectric-block phase shifter can be minimized by appropriately varying the individual distance between each phase-shifting stage. This thesis also investigates 3D micromachined substrate-integrated W-band helical antennas. In contrast to conventional on-chip antenna designs that only utilize the surface of the wafer, the novel helical radiator is fully embedded into the substrate, thereby utilizing the whole volume of the wafer and resulting in a compact high-gain antenna design. The performance of the antenna is substantially enhanced by properly etching the substrate, tailor making the antenna core, and by modifying size and geometry of the substrate-integrated ground plane. A linear line antenna array is composed of eight radiating elements and is demonstrated by simulations. Each antenna is connected to the input port through a multi-stage 3-dB power divider. The input and output of the single-stage 3-dB power divider is well matched to the 50-Ω impedance by four-section Chebyshev transformers. The simulation results indicate that the novel helical antenna arrays offer a narrow radiation beam with an excellent radiation gain that result in high-resolution scan angles on the azimuth plane. The proposed helical antenna structures can be fabricated by employing standard cleanroom micromachining processes.
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| 8. |
- Sterner, Mikael, 1981-
(author)
-
Monocrystalline-Silicon Based RF MEMS Devices
- 2012
-
Doctoral thesis (other academic/artistic)abstract
- This thesis presents novel radio-frequency microelectromechanical (RF MEMS) devices, for microwave and millimeter wave applications, designed for process robustness and operational reliability using monocrystalline silicon as structural material. Two families of RF MEMS devices are proposed. The first comprises reconfigurable microwave components integrated with coplanar-waveguide transmission lines in the device layer of silicon-on-insulator wafers. The second consists of analog tuneable millimeter wave high-impedance surface arrays.The first group of reconfigurable microwave components presented in this thesis is based on a novel concept of integrating MEMS functionality into the sidewalls of three-dimensional micromachined transmission lines. A laterally actuated metal-contact switch was implemented, with the switching mechanism completely embedded inside the signal line of a coplanar-waveguide transmission line. The switch features zero power-consumption in both the on and the off state since it is mechanically bistable, enabled by interlocking hooks. Both two-port and three-port configurations are presented. Furthermore, tuneable capacitors based on laterally moving the ground planes in a micromachined coplanar-waveguide transmission line are demonstrated.The second group of reconfigurable microwave components comprises millimeter-wave high-impedance surfaces. Devices are shown for reflective beam steering, reflective stub-line phase shifters and proximity based dielectric rod waveguide phase shifters, as well as a steerable leaky-wave antenna device based on the same geometry. Full wafer transfer bonding of symmetrically metallized monocrystalline silicon membranes, for near-ideal stress compensation, is used to create large arrays of distributed MEMS tuning elements. Furthermore, this thesis investigates the integration of reflective MEMS millimeter wave devices in rectangular waveguides using a conductive adhesive tape, and the integration of substrates with mismatched coefficients of thermal expansion.
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| 9. |
- Xinghai, Zhao, 1984-
(author)
-
Advanced MEMS Technology for Terahertz Frequencies
- 2021
-
Doctoral thesis (other academic/artistic)abstract
- With the development of terahertz (THz) technology, a variety of application demands are growing rapidly, such as high-rate communications, THz radars, environmental monitoring, medical imaging, and space exploration. However, the fabrication, integration, and packaging techniques for THz components and systems pose great challenges for a large-scale, cost-effective production. The current THz technology relies on the conventional and expensive serial fabrication and packaging techniques, such as computer numerical control (CNC) high-precision machining, which are suitable only for high-end research instrumentation or one-off prototypes. Nowadays, THz microelectromechanical system (MEMS) is a leading candidate to realize high-precision, low-cost, large-volume fabrication, and integration for miniaturized THz components and systems. In this thesis, several key components and technologies of THz MEMS are developed towards the progression of future THz microsystem front-ends.In the following research, D-band filters and diplexers have been implemented by an advanced Si micromachining technology based on a releasable-filling-structure (RFS) approach which can achieve high-precision geometries for THz waveguide devices. Fabrication imperfection is a big issue which affects the performance of the devices, namely, insertion loss, bandwidth, and operation frequency. The RFS-based silicon-on-insulator (SOI) micromachining technology improves the deep reactive ion etching (DRIE) processing performance, especially sidewall verticality, by utilizing extra structures to fill the large areas, which in turn, can obtain uniform etching aspect ratios.The state-of-the-art MEMS phase shifter based on a waveguide-integrated SOI micromachining technology has been successfully demonstrated at 220-330 GHz, with a full-band and low insertion-loss characterization. MEMS comb-drive actuators are integrated in the device layer of the SOI substrate, which move Si slabs in a rectangular waveguide of the handle layer for changing the propagation constant. Integrating tunability or reconfigurability into THz microsystems is a very crucial aspect for implementing signal modulation, frequency band selection, beam scanning, and calibration applications in THz MEMS front-ends. The demonstrated work paves the way towards a three-dimensional (3D)-micromachined, SOI integrated rectangular waveguide microsystem.A series of high-Q multilayer filters have been achieved by a vertically stacked Si-chip micromachining technology. The frequencies cover 270 GHz, 300 GHz, 450 GHz, 687 GHz and 700 GHz. The fabrication accuracy and repeatability of this kind of THz waveguide filters based on this vertically stacked multilayer platform have been investigated by experiments. A versatile axial-port-integrated multilayer device concept has been proposed for enabling the direct on-flange characterization and integration for advanced THz waveguide components. H-plane waveguide filters with versatile axial-interfaces based on the vertically stacked multilayer platform has been successfully demonstrated. This vertically stacked multilayer Si micromachining technology shows a promising potential in implementing highly integrated, compact 3D THz microsystems.
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| 10. |
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| 11. |
- Anoshkin, Ilya V., et al.
(author)
-
Freeze-Dried Carbon Nanotube Aerogels for High-Frequency Absorber Applications
- 2018
-
In: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 10:23, s. 19806-19811
-
Journal article (peer-reviewed)abstract
- A novel technique for millimeter wave absorber material embedded in a metal waveguide is proposed. The absorber material is a highly porous carbon nanotube (CNT) aerogel prepared by a freeze-drying technique. CNT aerogel structures are shown to be good absorbers with a low reflection coefficient, less than -12 dB at 95 GHz. The reflection coefficient of the novel absorber is 3-4 times lower than that of commercial absorbers with identical geometry. Samples prepared by freeze-drying at -25 degrees C demonstrate resonance behavior, while those prepared at liquid nitrogen temperature (-196 degrees C) exhibit a significant decrease in reflection coefficient, with no resonant behavior. CNT absorbers of identical volume based on wet-phase drying preparation show significantly worse performance than the CNT aerogel absorbers prepared by freeze-drying. Treatment of the freeze-dried CNT aerogel with n- and p-dopants (monoethanolamine and iodine vapors, respectively) shows remarkable improvement in the performance of the waveguide embedded absorbers, reducing the reflection coefficient by 2 dB across the band.
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| 12. |
- Arsanjani, Arash, et al.
(author)
-
A Silicon Micromachined Cascaded Singlet Filtering Antenna at 270 GHz
-
Other publication (other academic/artistic)abstract
- This paper discusses the steps and challenges of implementing a cascaded singlet filtenna using silicon deep reactive ion etching (DRIE) technology. Two fourth-order filtennas with a center frequency of 270~GHz, 14~GHz bandwidth, and a 20~dB inband return loss are fabricated and measured to verify the proposed concept. The measured single-slot and dual-slot filtenna have a peak radiation gain of X~dBi, and Y~dBi at 270~GHz, respectively. Moreover, the challenges and details of silicon micromachining in fabricating these antennas are discussed.Comprehensive details regarding the synthesis procedure, confirmation via simulation, and measurement outcomes are thoroughly explained.
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| 13. |
- Baghchehsaraei, Zargham, et al.
(author)
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MEMS 30μm-thick W-band waveguide switch
- 2012
-
In: European Microwave Week 2012. - : Institute of Electrical and Electronics Engineers (IEEE). ; , s. 1055-1058, s. 675-678, s. 1055-1058
-
Conference paper (peer-reviewed)abstract
- This paper presents for the first time a novel concept of a MEMS waveguide switch based on a reconfigurable surface, whose working principle is to short-circuit or to allow for free propagation of the electrical field lines of the TE10 mode of a WR-12 rectangular waveguide. This transmissive surface is only 30μm thick and consists of up to 1260 reconfiguring cantilevers in the waveguide cross-section, which are moved simultaneously by integrated MEMS comb-drive actuators. For the first fabrication run, the yield of these reconfigurable elements on the chips was 80-86%, which still was good enough for resulting in a measured insertion loss in the open state of better than 1dB and an isolation of better than 20dB for the best designs, very wideband from 62 to 75GHz. For 100% fabrication yield, HFSS simulations predict that an insertion loss in the open state of better than 0.1dB and an isolation of better than 30dB in the closed state are possible for designs with 800 and more contact points for this novel waveguide switch concept.
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| 14. |
- Bartlett, Chad, et al.
(author)
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Compact Triangular-Cavity Singlet-Based Filters in Stackable Multi-Layer Technologies
- 2022
-
In: IEEE Transactions on Terahertz Science and Technology. - : Institute of Electrical and Electronics Engineers (IEEE). - 2156-342X .- 2156-3446. ; 12:5, s. 540-543
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Journal article (peer-reviewed)abstract
- In this letter, triangular-cavity bandpass filters are investigated in stackable multilayer technologies in order to achieve highly compact designs with reduced fabrication complexity. The triangular-shaped cavities are first introduced in the form of singlets and then expanded on as a novel method for achieving a quasi-triplet filter response, where the filter's input and output irises are utilized as resonating means for two additional passband poles. Exploitation of this advanced singlet scheme exemplifies innovative use of resonant irises for achieving highly compact filters that can be manufactured with simple multilayer fabrication steps for use in future terahertz applications.
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| 15. |
- Beuerle, Bernhard, 1983-, et al.
(author)
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A CPW Probe to Rectangular Waveguide Transition for On-wafer Micromachined Waveguide Characterization
-
Other publication (other academic/artistic)abstract
- A new transition from coplanar waveguide probe to micromachined rectangular waveguide for on-wafer device characterization is presented in this article. The transition is fabricated in the same double H-plane split silicon micromachined waveguide technology as the devices under test, requiring no additional post-processing or assembly steps. We outline the design and fabrication process of the transition for the frequency band of 220 – 330 GHz. A coplanar waveguide structure acts as the probing interface, with an E-field probe protruding in the waveguide cavity exciting the fundamental waveguide mode. Guard structures around the E-field probe increase the aspect ratio during deep reactive ion etching and secure its geometry. A full equivalent circuit model is provided by analyzing its working principle. RF characterization of fabricated devices is performed for both single-ended and back-to-back configurations. Measured S-parameters of the single-ended transition are obtained by applying a two-tiered calibration and are analyzed using the equivalent circuit model. The insertion loss of the single-ended transition lies between 0.3 dB and 1.5 dB over the whole band, with the return loss in excess of 8 dB. In addition to previously reported characterization of a range of devices under test the viability of the transition for on-wafer device calibration is demonstrated by characterizing a straight waveguide line, achieving an insertion loss per unit length of 0.02 – 0.08 dB/mm in the frequency band of 220 – 330 GHz.
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| 16. |
- Beuerle, Bernhard, 1983-, et al.
(author)
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A CPW Probe to Rectangular Waveguide Transition for On-Wafer Micromachined Waveguide Characterization
- 2024
-
In: IEEE Transactions on Terahertz Science and Technology. - : Institute of Electrical and Electronics Engineers (IEEE). - 2156-342X .- 2156-3446. ; 14:1, s. 98-108
-
Journal article (peer-reviewed)abstract
- A new transition from coplanar waveguide probe to micromachined rectangular waveguide for on-wafer device characterization is presented in this article. The transition is fabricated in the same double H-plane split silicon micromachined waveguide technology as the devices under test, requiring no additional post-processing or assembly steps. We outline the design and fabrication process of the transition for the frequency band of 220–330 GHz. A coplanar waveguide structure acts as the probing interface, with an E-field probe protruding in the waveguide cavity exciting the fundamental waveguide mode. Guard structures around the E-field probe increase the aspect ratio during deep reactive ion etching and secure its geometry. A full equivalent circuit model is provided by analyzing its working principle. RF characterization of fabricated devices is performed for both single-ended and back-to-back configurations. Measured S-parameters of the single-ended transition are obtained by applying a two-tiered calibration and are analyzed using the equivalent circuit model. The insertion loss of the single-ended transition lies between 0.3 dB and 1.5 dB over the whole band, with the return loss in excess of 8 dB. In addition to previously reported characterization of a range of devices under test the viability of the transition for on-wafer device calibration is demonstrated by characterizing a straight waveguide line, achieving an insertion loss per unit length of 0.02–0.08 dB/mm in the frequency band of 220–330 GHz.
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| 17. |
- Beuerle, Bernhard, 1983-, et al.
(author)
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A Very Low Loss 220–325 GHz Silicon Micromachined Waveguide Technology
- 2018
-
In: IEEE Transactions on Terahertz Science and Technology. - : IEEE. - 2156-342X .- 2156-3446. ; 8:2, s. 248-250
-
Journal article (peer-reviewed)abstract
- This letter reports for the first time on a very low loss silicon micromachined waveguide technology, implemented for the frequency band of 220–325 GHz. The waveguide is realized by utilizing a double H-plane split in a three-wafer stack. This ensures very low surface roughness, in particular on the top and bottom surfaces of the waveguide, without the use of any surface roughness reduction processing steps. This is superior to previous micromachined waveguide concepts, including E-plane and single H-plane split waveguides. The measured average surface roughness is 2.14 nm for the top/bottom of the waveguide, and 163.13 nm for the waveguide sidewalls. The measured insertion loss per unit length is 0.02–0.07 dB/mm for 220–325 GHz, with a gold layer thickness of 1 μm on the top/bottom and 0.3 μm on the sidewalls. This represents, in this frequency band, the lowest loss for any silicon micromachined waveguide published to date and is of the same order as the best metal waveguides.
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| 18. |
- Beuerle, Bernhard, 1983-, et al.
(author)
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Integrating InP MMICs and Silicon Micromachined Waveguides for sub-THz Systems
-
Other publication (other academic/artistic)abstract
- A novel co-designed transition from InP monolithic microwave integrated circuits to silicon micromachined waveguides is presented. The transition couples a microstrip line to a substrate waveguide sitting on top of a vertical waveguide. The silicon part of the transition consists of a top and a bottom chip, fabricated in a very low-loss silicon micromachined waveguide technology using silicon on insulator wafers. The transition has been designed, fabricated and characterized for 220–330 GHz in a back-to-back configuration. Measured insertion loss is 3–6 dB at 250–300 GHz, and return loss is in excess of 5 dB.
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| 19. |
- Beuerle, Bernhard, et al.
(author)
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Integrating InP MMICs and Silicon Micromachined Waveguides for Sub-THz Systems
- 2023
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In: IEEE Electron Device Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 0741-3106 .- 1558-0563. ; 44:10, s. 1800-1803
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Journal article (peer-reviewed)abstract
- A novel co-designed transition from InP monolithic microwave integrated circuits to silicon micromachined waveguides is presented. The transition couples a microstrip line to a substrate waveguide sitting on top of a vertical waveguide. The silicon part of the transition consists of a top and a bottom chip, fabricated in a very low-loss silicon micromachined waveguide technology using silicon on insulator wafers. The transition has been designed, fabricated and characterized for 220 GHz to 330 GHz in a back-to-back configuration. Measured insertion loss is 3 dB to 6 dB at 250 GHz to 300 GHz , and return loss is in excess of 5 dB.
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| 20. |
- Beuerle, Bernhard, 1983-, et al.
(author)
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Low-Loss Silicon Micromachined Waveguides Above 100 GHz Utilising Multiple H-plane Splits
- 2018
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In: Proceedings of the 48th European Microwave Conference, Madrid, October 1-3, 2018. - : Institute of Electrical and Electronics Engineers (IEEE). - 9782874870514 ; , s. 1041-1044
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Conference paper (peer-reviewed)abstract
- For sub-millimeter and millimeter wave applications rectangular waveguides are an ideal transmission medium. Compared to conventional, metal-milled rectangular waveguides, silicon micromachined waveguides offer a number of advantages. In this paper we present a low-loss silicon micromachined waveguide technology based on a double H-plane split for the frequency bands of 110 – 170 GHz and 220 – 330 GHz. For the upper band a reduced height waveguide is presented, which achieves a loss per unit length of 0.02 – 0.10 dB/mm. This technology has been further adapted to implement a full height waveguide for the lower frequency band of 110 – 170 GHz. The full height waveguide takes advantage of the benefits of the double H-plane split technique to overcome the challenges of fabricating micromachined waveguides at lower frequencies. With measured insertion loss of 0.007 – 0.013 dB/mm, averaging 0.009 dB/mm over the whole band, this technology offers the lowest insertion loss of any D-band waveguide to date. The unloaded Q factor of the D-band waveguide technology is estimated to be in excess of 1600, while a value of 750 has been measured for the reduced height upper band waveguide.
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| 21. |
- Beuerle, Bernhard, 1983-, et al.
(author)
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Micromachined Waveguides with Integrated Silicon Absorbers and Attenuators at 220–325 GHz
- 2018
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In: IEEE MTT-S International Microwave Symposium, IEEE conference proceedings, 2018. - : IEEE.
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Conference paper (peer-reviewed)abstract
- This paper reports for the first time on micromachined waveguides with integrated micromachined silicon absorbers. In contrast to epoxy-based microwave absorbers, micromachined lossy silicon absorbers are fully compatible with high temperature fabrication and assembly processes for micromachined waveguides. Furthermore, micromachining enables the fabrication of exact, near ideal taper tips for the silicon absorbers, whereas the tip of epoxy-based absorbers cannot be shaped accurately and reproducibly for small waveguides. Silicon of different conductivity is a very well understood and characterized dielectric material, in contrast to conventional absorber materials which are not specified above 60 GHz. Micromachined silicon waveguides with integrated absorbers and attenuators were designed, fabricated and characterized in the frequency band of 220 – 325 GHz. The return and insertion loss for various taper-geometry variations of double-tip tapered absorbers and attenuators was studied. The average return loss for the best investigated device is 19 dB over the whole band. The insertion loss of the two-port attenuators is 16 – 33 dB for different designs and shows an excellent agreement to the simulated results. The best measured devices of the one-port absorbers exhibit an average and worst-case return loss of 22 dB and 14 dB, respectively, over the whole band. The return loss is not characterized by a good simulation-measurement match, which is most likely attributed to placement tolerances of the absorbers in the waveguide cavities affecting the return but not the insertion loss.
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| 22. |
- Beuerle, Bernhard, 1983-, et al.
(author)
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On-wafer Micromachined Waveguide Characterization with CPW Probe to Rectangular Waveguide Transition up to 500 GHz
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Other publication (other academic/artistic)abstract
- We report on coplanar waveguide to micromachined waveguide transitions for on-wafer device characterization. The transitions are designed in a silicon micromachined waveguide technology using silicon on insulator wafers together with the devices under test. A previous design at 220–330 GHz with in-band radiation characteristic is modified to eliminate the radiation and allow it to be scaled to higher frequencies. Simulation results for 220–330 GHz and 330–500 GHz are obtained, and the transition has an insertion loss of better than 0.5 and 1.2 dB, respectively. The transition is fabricated and characterized at 220–330 GHz, with an insertion loss of better than 0.7 dB and a return loss in excess of 10 dB over the whole band.
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| 23. |
- Boonlom, Kamol, et al.
(author)
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Advanced Studies on Optical Wireless Communications for in-Pipe Environments : Bandwidth Exploration and Thermal Management
- 2024
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In: IEEE Access. - : Institute of Electrical and Electronics Engineers (IEEE). - 2169-3536. ; 12, s. 80607-80632
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Journal article (peer-reviewed)abstract
- This study presents insights into high-speed optical wireless communication (OWC) within plastic pipes, introducing a Gbps-capable alternative for challenging environments. Utilizing a 1W LED with five wavelengths, the experiment explores signal power, attenuation, and bandwidth characteristics. Notably, the blue LED achieves an unprecedented 58.64 MHz bandwidth, red and purple LEDs demonstrate novel bandwidths of approximately 25.23 MHz, and green and yellow LEDs exhibit unique bandwidths of 23.75 MHz and 9.62 MHz, respectively. The attenuation parameters for different wavelengths provide numerous insights, showcasing the novelty of this research and its potential applications in robot communication within plastic pipes. Concurrently, the paper introduces an approach to address the temperature impact on five distinct wavelength LEDs in OWC. By focusing on variations in LED bandwidth and optical power, an optimal heat sink design is proposed. This design achieves a remarkable minimum temperature of 27.06 degrees C and reduces the chip LED device's response time from 15 to 9 seconds. The significance lies in the novelty of the proposed heat sink, which incorporates variables such as fin thickness, height, air gap width, number of fins, and airflow rate, marking a substantial advancement in thermal management for OWC systems.
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| 24. |
- Campion, James, 1989-, et al.
(author)
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An Ultra Low-Loss Silicon-Micromachined Waveguide Filter for D-Band Telecommunication Applications
- 2018
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In: 2018 IEEE/MTT-S International Microwave Symposium. - : IEEE. - 9781538650677 ; , s. 583-586
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Conference paper (peer-reviewed)abstract
- A very low-loss micromachined waveguide bandpassfilter for use in D-band (110–170GHz) telecommunication applicationsis presented. The 134–146GHz filter is implemented in a silicon micromachined technology which utilises a double H-plane split, resulting in significantly lower insertion loss than conventional micromachined waveguide devices. Custom split-blocks are designed and implemented to interface with the micromachined component. Compact micromachined E-plane bends connect the split-blocks and DUT. The measured insertion loss per unit length of the waveguide technology (0.008–0.016 dB/mm) is the lowest reported to date for any micromachined waveguide at D-band. The fabricated 6-pole filter, with a bandwidth of 11.8 GHz (8.4%), has a minimum insertion loss of 0.41 dB, averaging 0.5 dB across its 1 dB bandwidth, making it the lowest-loss D-band filter reported to date in any technology. Its return loss is better than 20 dB across 85% of the same bandwidth. The unloaded quality factor of a single cavity resonator implemented in this technology is estimated to be 1600.
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| 25. |
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