232 results found
Sun J, Lucyszyn S, 2018, Extracting Complex Dielectric Properties From Reflection-Transmission Mode Spectroscopy, IEEE ACCESS, Vol: 6, Pages: 8302-8321, ISSN: 2169-3536
Otter W, Ridler NM, Lucyszyn S, 2017, 3D printed waveguides: A revolution in low volume manufacturing for the 21st century, ARMMS RF & Microwave Society Conference, Publisher: ARMMS RF & Microwave Society, Pages: 1-6
3D printing is a disruptive technology, offering the inherent capabilities for creating truly arbitrary 3D structures, with low manufacturing costs associated with low volume production runs. This paper provides an overview of the current progress in 3D printing of metal-pipe rectangular waveguide (MPRWG) components, from 10 GHz to 1 THz, at Imperial College London. First, measurements performed at the UK National Physical Laboratory demonstrate that 3D printed MPRWG performance is comparable to standard commercial waveguides at X-band and W-band. Then, a fully 3D printed X-band dielectric flap tuneable phase shifter and W-band 6th-order inductive iris bandpass filter are demonstrated experimentally. Finally, an optically-controlled 500 GHz IQ vector modulator will also be presented; packaged laser diodes and high resistivity silicon implants are integrated within a hybrid 3D printed split-block module, representing a paradigm shift in additive manufacturing for realizing tuneable THz applications.
Otter WJ, Lucyszyn S, 2017, Printing: the future of THz, Electronics Letters, Vol: 53, Pages: 443-443, ISSN: 0013-5194
3D printing allows for record-breaking, low-cost waveguides operating at 1.1 THz
Hanham SM, Ahmad MM, Lucyszyn S, et al., 2017, LED-Switchable High-Q Packaged THz Microbeam Resonators, IEEE TRANSACTIONS ON TERAHERTZ SCIENCE AND TECHNOLOGY, Vol: 7, Pages: 199-208, ISSN: 2156-342X
Muller AA, Sanabria-Codesal E, Moldoveanu A, et al., 2017, Extended Capabilities of the 3-D Smith Chart With Group Delay and Resonator Quality Factor, IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, Vol: 65, Pages: 10-19, ISSN: 0018-9480
Otter W, Lucyszyn S, 2016, Hybrid 3-D-printing technology for tunable THz applications, Proceedings of the IEEE, Vol: 105, Pages: 756-767, ISSN: 0018-9219
In recent years, additive manufacturing has experienced rapid growth, due to its inherent capabilities for creating arbitrary 3-D structures, accessibility and associated low manufacturing costs. This paper first reviews the state of the art in 3-D printing for terahertz (THz) applications and identifies the critical features required for such applications. The future potential for this technology is demonstrated experimentally with the first 3-D printed, optically-controlled THz I-Q vector modulator. Here, miniature high-resistivity silicon implants are integrated into metal-pipe rectangular waveguides. The 3-D printed split-block assembly also includes two packaged infrared laser diodes and a heat sink. The measured performance of a proof-of-principle 4-QAM vector modulator that can operate up to 500 GHz is reported. This new hybrid 3-D printing THz technology, which combines semiconductor devices with potentially low cost, high performance passive guided-wave structures represents a paradigm shift and may prove to be an ideal solution for implementing affordable transceivers in future ubiquitous THz applications.
Muller A, Sanabria-Codesal E, Lucyszyn S, 2016, Computational cost reduction for N+2 order coupling matrix synthesis based on Desnanot-Jacobi identity, IEEE Access, Vol: 4, Pages: 10042-10050
Matrix inversion is routinely performed in computational engineering, with coupling matrix filter synthesis considered here as just one of many example applications. When calculating the elements of the inverse of a matrix, the determinants of the submatrices are evaluated. The recent mathematical proof of the Desnanot-Jacobi (also known as the “Lewis Carol”) identity shows how the determinant of an N+2 order square matrix can be directly computed from the determinants of the N+1 order principal submatrices and N order core submatrix. For the first time, this identity is applied directly to an electrical engineering problem, simplifying N+2 order coupled matrix filter synthesis (general case, which includes lossy and asymmetrical filters). With the general two-port network theory, we prove the simplification using the Desnanot-Jacobi identity and show that the N+2 coupling matrix can be directly extracted from the zeros of the admittance parameters (given by N+1 order determinants) and poles of the impedance parameters (given by the N order core matrix determinant). The results show that it is possible to decrease the computational complexity (by eliminating redundancy), reduce the associated cost function (by using less iterations), and under certain circumstances obtain different equivalent solutions. Nevertheless, the method also proves its practical usefulness under constrained optimizations when the user desires specific coupling matrix topologies and constrained coefficient values (e.g, purely real/imaginary/positive/negative). This can lead to a direct coupling matrix constrained configuration where other similar methods fail (using the same optimization algorithms).
Sun J, Hu F, Lucyszyn S, 2016, Predicting Atmospheric Attenuation under Pristine Conditions between 0.1 and 100 THz, IEEE Access, Vol: 4, Pages: 9377-9399, ISSN: 2169-3536
This multidisciplinary article reports on a research application-led study for predicting atmospheric attenuation, and tries to bridge the knowledge gap between applied engineering and atmospheric sciences. As a useful comparative baseline, the paper focuses specifically on atmospheric attenuation under pristine conditions, over the extended terahertz spectrum. Three well-known simulation software packages are compared and contrasted ('HITRAN on the Web', MODTRAN(RM)4 and LBLRTM). Techniques used for modeling atmospheric attenuation have been applied to investigate the resilience of (ultra-)wide fractional bandwidth applications ('THz Torch') to the effects of molecular absorption. Two extreme modeling scenarios are investigated: horizontal path links at sea level and Earth-space path links. It is shown by example that a basic software package ('HITRAN on the Web') can give good predictions with the former; whereas sophisticated simulation software (LBLRTM) is required for the latter. Finally, with molecular emission included, carrier-to-noise ratio fade margins can be calculated for the effects of line broadening due to changes in macroscopic atmospheric conditions with sub-1 THz ultra-narrow fractional bandwidth applications. Outdoors can be far from pristine, with additional atmospheric contributions only briefly introduced here; further discussion is beyond the scope of this study, but relevant references have been cited.
Hu F, Lucyszyn S, 2016, Advances in Front-end Enabling Technologies for Thermal Infrared 'THz Torch' Wireless Communications, JOURNAL OF INFRARED MILLIMETER AND TERAHERTZ WAVES, Vol: 37, Pages: 881-893, ISSN: 1866-6892
Mitcheson PD, Lucyszyn S, Pinuela M, et al., 2016, RF energy harvester, US9837865B2
Disclosed herein is an antenna apparatus for use in harvesting ambient radio frequency, RF, energy. The apparatus comprises one or more RF antenna components arranged to receive RF energy for producing electricity. The one or more RF antenna components comprise a plurality of frequency filtering components, each frequency filtering component being arranged to filter a respective frequency band of the received RF energy. Also disclosed herein is an apparatus comprising a rectifying circuit arranged to convert a variable electrical signal received at an input from an associated antenna into a direct current electrical signal for supplying to an electrical energy storage unit, the antenna for use in harvesting ambient radio frequency, RF, energy. The apparatus also comprises a power management module having an input arranged to receive the direct current and control supply of the direct current to the electrical energy storage unit. The rectifying circuit comprises a plurality of transmission lines, wherein the input of the rectifying circuit and the input of the power management module are connected via the plurality of transmission lines. The power management module is arranged at least partially within a boundary defined by the plurality of transmission lines.
Otter WJ, Lucyszyn S, 2016, 3-D Printing of Microwave Components for 21st Century Applications, IEEE MTT-S International Microwave Workshop Series on Advanced Materials and Processes for RF and THz Applications (IMWS-AMP), Publisher: IEEE
Otter WJ, Hanham SM, Klein N, et al., 2016, Millimeter-wave negative group delay network, URSI Asia-Pacific Radio Science Conference (URSI AP-RASC), Publisher: IEEE, Pages: 1205-1207
Klein N, Watts C, Hanham SM, et al., 2016, Microwave-to-terahertz dielectric resonators for liquid sensing in microfluidic systems, Conference on Terahertz Emitters, Receivers, and Applications VII, Publisher: SPIE-INT SOC OPTICAL ENGINEERING, ISSN: 0277-786X
Muller AA, Lucyszyn S, 2015, Properties of purely reactive Foster and non-Foster passive networks, ELECTRONICS LETTERS, Vol: 51, Pages: 1882-1883, ISSN: 0013-5194
D'Auria M, Otter WJ, Hazell J, et al., 2015, 3-D Printed Metal-Pipe Rectangular Waveguides, IEEE TRANSACTIONS ON COMPONENTS PACKAGING AND MANUFACTURING TECHNOLOGY, Vol: 5, Pages: 1339-1349, ISSN: 2156-3950
Mitcheson PD, Lucyszyn S, Pinuela M, et al., 2015, Inductive power transfer system, US9899877B2
An inductive power transfer system comprises a transmitter circuit comprising a transmitter coil and a receiver circuit comprising a receiver coil spaced from the transmitter coil. The transmitter circuit is in the form of a Class E amplifier with a first inductor and a transistor in series between the terminals of a power supply. A first transmitter capacitance is in parallel with the transistor between the first inductor and a power supply terminal, a primary tank circuit in parallel with the first transmitter capacitance, the primary tank circuit comprising the transmitter coil and a second transmitter capacitance arranged in parallel with the transmitter coil, and a third transmitter capacitance in series with the first inductor between the first transmitter capacitance and the primary tank circuit. The second transmitter capacitance is selected such that a resonant frequency of the primary tank circuit is not equal to the first frequency.
Hanham SM, Watts C, Otter WJ, et al., 2015, Dielectric measurements of nanoliter liquids with a photonic crystal resonator at terahertz frequencies, APPLIED PHYSICS LETTERS, Vol: 107, ISSN: 0003-6951
Papantonis S, Lucyszyn S, 2015, Lossy Spherical Cavity Resonators for Stress-testing Arbitrary 3D Eigenmode Solvers, Progress in Electromagnetics Research, Vol: 151, Pages: 151-167, ISSN: 1070-4698
A lossy metal-wall cavity resonator that extends well beyond perturbation theory limitsis studied. An exact analytical solution is employed for the spherical cavity resonator, having wallstransformed from being a perfect electrical conductor (PEC) to free space. This model then acts as anideal benchmark reference standard. A plane-wave approximation is then derived. Independent full-wavenumerical modeling of the spherical cavity resonator is undertaken using eigenmode solvers within twowell-known commercial, industry-standard, simulation software packages (HFSSTMand COMSOL). Ithas been found that the plane-wave approximation model accurately characterizes the results generatedby these solvers when equivalent ¯nite conductivity boundary (FCB) and layered impedance boundary(LIB) conditions are used. However, the impedance boundary (IB) condition is accurately characterizedby the exact model, but the precise value of complex wave impedance at the wall boundary for the specificresonance mode must first be known a priori. Our stress-testing results have profound implications onthe usefulness of these commercial solvers for accurately predicting eigenfrequencies of lossy arbitrary3D structures. For completeness, an exact series RLC equivalent circuit model is given specifcallyfor a spherical cavity resonator having arbitrary wall losses, resulting in the derivation of an extendedperturbation model.
Hu F, Sun J, Brindley HE, et al., 2015, Systems Analysis for Thermal Infrared 'THz Torch' Applications, Journal of Infrared, Millimeter, and Terahertz Waves, Vol: 36, Pages: 474-495, ISSN: 1866-6892
The ‘THz Torch’ concept was recently introduced by the authors for providing secure wireless communications over short distances within the thermal infrared (10-100 THz). Unlike conventional systems, thermal infrared can exploit front-end thermodynamics with engineered blackbody radiation. For the first time, a detailed power link budget analysis is given for this new form of wireless link. The mathematical modeling of a short end-to-end link is provided, which integrates thermodynamics into conventional signal and noise power analysis. As expected from the Friis formula for noise, it is found that the noise contribution from the pyroelectric detector dominates intrinsic noise. From output signal and noise voltage measurements, experimental values for signal-to-noise ratio (SNR) are obtained and compared with calculated predictions. As with conventional communications systems, it is shown for the first time that the measured SNR and measured bit error rate found with this thermodynamics-based system resembles classical empirical models. Our system analysis can serve as an invaluable tool for the development of thermal infrared systems, accurately characterizing each individual channel and, thus, enables the performance of multi-channel ‘THz Torch’ systems to be optimized.
Hu F, Lucyszyn S, 2015, Modelling Miniature Incandescent Light Bulbs for Thermal Infrared ‘THz Torch’ Applications, Journal of Infrared, Millimeter, and Terahertz Waves, Vol: 36, Pages: 350-367, ISSN: 1866-6892
The ‘THz Torch’ concept is an emerging technology that was recently introduced by the authors for implementing secure wireless communications over short distances within the thermal infrared (20-100 THz, 15 μm to 3 μm). In order to predict the band-limited output radiated power from ‘THz Torch’ transmitters, for the first time, this paper reports on a detailed investigation into the radiation mechanisms associated with the basic thermal transducer. We demonstrate how both primary and secondary sources of radiation emitted from miniature incandescent light bulbs contribute to the total band-limited output power. The former is generated by the heated tungsten filament within the bulb, while the latter is due to the increased temperature of its glass envelope. Using analytical thermodynamic modelling, the band-limited output radiated power is calculated, showing good agreement with experimental results. Finally, the output radiated power to input DC power conversion efficiency for this transducer is determined, as a function of bias current and operation within different spectral ranges. This modelling approach can serve as an invaluable tool for engineering solutions that can achieve optimal performances with both single and multi-channel ‘THz Torch’ systems.
Hu F, Otter WJ, Lucyszyn S, 2015, Optically Tunable THz Frequency Metamaterial Absorber, 40th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz), Publisher: IEEE, ISSN: 2162-2027
Jose Sanchez-Martinez J, Marquez-Segura E, Lucyszyn S, 2015, Synthesis and Design of High-Selectivity Wideband Quasi-Elliptic Bandpass Filters Using Multiconductor Transmission Lines, IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, Vol: 63, Pages: 198-208, ISSN: 0018-9480
Sun J, Hu F, Wang Z, et al., 2015, Banknote Characterization using a Thermal Infrared 'THz Torch' Spectrometer, Asia-Pacific Microwave Conference (APMC), Publisher: IEEE
Muller AA, Sanabria-Codesal E, Moldoveanu A, et al., 2014, Apollonius unilateral transducer constant power gain circles on 3D Smith charts, ELECTRONICS LETTERS, Vol: 50, Pages: 1531-1532, ISSN: 0013-5194
Papantonis S, Ridler NM, Wilson A, et al., 2014, Reconfigurable Waveguide for Vector Network Analyzer Verification, IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, Vol: 62, Pages: 2415-2422, ISSN: 0018-9480
Otter WJ, Hanham SM, Ridler NM, et al., 2014, 100 GHz ultra-high Q-factor photonic crystal resonators, SENSORS AND ACTUATORS A-PHYSICAL, Vol: 217, Pages: 151-159, ISSN: 0924-4247
Otter WJ, Hu F, Hazell JF, et al., 2014, THz metal mesh filters on electrically thick fused silica substrates, Infrared Milliemter-Wave andTHz Waves Conference, Publisher: IEEE
This paper shows simulated and measured results of ultra-low cost metal mesh filters on electrically thick substrates for millimeter-wave and THz bands. It provides a broad overview of metal mesh filters currently available and suggest why it is worth moving to an electrically thick substrate for ultra-low cost applications. We demonstrate scalable traditional metal mesh filters on 525 μm thick fused silica substrates. In addition, trapped-mode excitation is exploited to improve out-of-band rejection at higher frequencies. The measured results prove that these filters are scalable in the THz range using cost-effective micromachining manufacturing. This work opens up the possibility of using electrically thick metal mesh filters for ultra-low cost applications.
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