| 1. |
- Gevorgian, Spartak, 1948, et al.
(author)
-
DC field induced antiferroelectric phase transition in bulk, single crystal strontium titanate
- 2001
-
In: Integrated Ferroelectrics. - : Informa UK Limited. - 1058-4587 .- 1607-8489. ; 33:1-4, s. 323-329
-
Journal article (peer-reviewed)abstract
- Dielectric hysteresis in bulk, single crystal SrTiO3 (STO) with YBa2Cu3O7. x(YBCO) electrodes is studied experimentally at 77K. In contrast with previously reported experiments [1], [2] the antiferroelectric phase transition is observed at higher temperature (i.e. 77K). The phase transition is observed where the crystal is cooled either with short circuited or with open circuited electrodes. The phase transition does not result in detectable changes in the microwave losses.
|
|
| 2. |
|
|
| 3. |
- Carlsson, Erik F., 1968, et al.
(author)
-
Arrangement and method relating to filtering of signals
- 2000
-
Patent (other academic/artistic)abstract
- A superconducting notch or band reject filter arrangement includes a superconducting dielectric resonator and a waveguide arrangement including a microstrip line to which the resonator is connected. The resonator is a parallel-plate resonator with a chip of a non-linear dielectric material device on which superconductors are arranged and the waveguide arrangement includes a contact device or a coupling device, the resonator being connected to the contact device of the waveguide arrangement in such a way that electric contact is provided, and the filter arrangement is frequency tuneable. Through the arrangement, the insertion losses are low
|
|
| 4. |
- Carlsson, Erik F., 1968, et al.
(author)
-
Effects of package width on K-band high-temperature superconducting filters
- 1995
-
In: Microwave and Optical Technology Letters. - : Wiley. - 1098-2760 .- 0895-2477. ; 10:6, s. 315-317
-
Journal article (peer-reviewed)abstract
- The effect of substrate/package width on filter performance is demonstrated and discussed for 18-GHz packaged filters using high-temperature superconducting (HTS), coupled microstrip lines. The filters are made of 0.3-μm YBa2Cu3O7 – ∂8 (YBCO) on MgO substrates with copper ground planes. The HTS filter shows a minimum insertion loss (IL) of 0.9 dB, steep skirts, and very good out-of-band rejection (> 45 dB up to 21 GHz) at 77 K with a bandwidth of 2.8% and a 0.3-dB ripple
|
|
| 5. |
- Eriksson, Anders, 1971, et al.
(author)
-
Mode chart of electrically thin parallel-plate circular resonators
- 2001
-
In: IEE Proceedings: Microwaves, Antennas and Propagation. - : Institution of Engineering and Technology (IET). - 1350-2417 .- 1359-706X. ; 148:1, s. 51 - 55
-
Journal article (peer-reviewed)abstract
- Modes in electrically thin circular parallel-plate resonators are discussed in detail. It is shown that the widely used mode indices (found from the field solutions) do not indicate the radial numbers of the field maximums in a straightforward manner. The diameter of the disc, not the radius, accommodates integer numbers of the field maximums (antinodes). These diametrical numbers are expressed in terms of radial mode indices. Emphasis is placed on the first axially symmetric mode TM020, which was incorrectly regarded as TM010 in the past. Some applications of the mode chart, including interpretation of experimental observations, are also discussed. Comparison is made with microstrip and annular resonators.
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
- Ferndahl, Mattias, 1973, et al.
(author)
-
A General Statistical Equivalent-Circuit-Based De-Embedding Procedure for High-Frequency Measurements
- 2008
-
In: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480 .- 1557-9670. ; 56:12, s. 2692-2700
-
Journal article (peer-reviewed)abstract
- A general equivalent-circuit-based method for the de-embedding of scattering parameters is presented. An equivalent circuit representation is used to model the embedding package. The parameters in the models are estimated with a statistical method using measured data from all de-embedding standards jointly together. Hence, it is possible to assess parameter estimates and their variance and covariance due to measurement uncertainties. A general de-embedding equation, which is valid for any five-port with a defined nodal admittance matrix, is derived and used in the subsequent de-embedding of measured device data. Different equivalent circuit models for the embedding network are then studied, and tradeoffs between model complexity and uncertainty are evaluated. Furthermore, the influence of varying number and combinations of de-embedding standards on the parameter estimates is investigated. The method is verified, using both measured and synthetic data, and compared against previously published work. It is found to be more general while keeping or improving accuracy.
|
|
| 9. |
- Fhager, Andreas, 1976, et al.
(author)
-
Clinical Diagnostics and Treatment with Electromagnetic Fields
- 2010
-
In: 4th European Conference on Antennas and Propagation, EuCAP 2010; Barcelona; Spain; 12 April 2010 through 16 April 2010. - 9788476534724 ; , s. C15P2-1
-
Conference paper (peer-reviewed)abstract
- There is a need for novel diagnostic and treatment systems to overcome the limitations with todays modalities. Microwave and THz based system has the potential to become both sensitive and specific in several applications. In this paper we discuss several applications that are currently being developed at the Chalmers University of Technology.
|
|
| 10. |
- Fhager, Andreas, 1976, et al.
(author)
-
Progress in clinical diagnostics and treatment with electromagnetic fields
- 2011
-
In: Proceedings of the 5th European Conference on Antennas and Propagation, EUCAP 2011. Rome, 11-15 April 2011. - 9788882020743 ; , s. 1936-1937
-
Conference paper (peer-reviewed)abstract
- There is a need for novel diagnostic and treatment systems to overcome the limitations with todays modalities. Microwave and THz based system has the potential to become both sensitive and specific in several applications. In this paper we discuss several applications that are currently being developed at the Chalmers University of Technology.
|
|
| 11. |
- Gevorgian, Spartak, 1948, et al.
(author)
-
Analytic approximation for open-end capacitance in symmetric coplanar-strip waveguides
- 2001
-
In: Electronics Letters. - : Institution of Engineering and Technology (IET). - 1350-911X .- 0013-5194. ; 37:20, s. 1226 - 1228
-
Journal article (peer-reviewed)abstract
- Conformal mapping and partial capacitance technique are used to derive simple and accurate closed form approximations for open-end capacitance in a symmetric coplanar-strip waveguide.
|
|
| 12. |
|
|
| 13. |
- Gevorgian, Spartak, 1948, et al.
(author)
-
CAD Model of a Gap in a Coplanar Waveguide
- 1996
-
In: International Journal of Microwave and Millimeter-Wave Computer-Aided Engineering. - 1050-1827. ; 6:5, s. 369-377
-
Journal article (peer-reviewed)abstract
- The partial capacitance approach and conformal mapping techniques are used to evaluate simple closed-form models for parallel and series capacitances of equivalent π-network of a symmetric gap in a CPW. Models are compared with experimental data and full wave analysis. They are useful for a wide range of CPW parameters and frequencies.
|
|
| 14. |
- Gevorgian, Spartak, 1948, et al.
(author)
-
CAD models for multilayered substrate interdigital capacitors
- 1996
-
In: IEEE Transactions on Microwave Theory and Techniques. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9480 .- 1557-9670. ; 44:6, s. 896 - 904
-
Journal article (peer-reviewed)abstract
- Conformal mapping-based models are given for interdigital capacitors on substrates with a thin superstrate and/or covering dielectric film. The models are useful for a wide range of dielectric constants and layer thicknesses. Capacitors with finger numbers n⩾2 are discussed. The finger widths and spacing between them may be different. The results are compared with the available data and some examples are given to demonstrate the potential of the models
|
|
| 15. |
- Gevorgian, Spartak, 1948, et al.
(author)
-
CAD Models for Shielded Multilayered CPW
- 1995
-
In: IEEE Transactions on Microwave Theory and Techniques. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9480 .- 1557-9670. ; 43:4, s. 772-779
-
Journal article (peer-reviewed)abstract
- Conformal mapping technique is used to obtain CAD oriented closed form analytical expressions for characteristic impedance per unit length capacitance and relative effective dielectric permittivity of top and bottom shielded multilayered coplanar waveguides (CPW). Analytical expressions are deduced for a wide verity of CPW structures
|
|
| 16. |
- Gevorgian, Spartak, 1948, et al.
(author)
-
Lower order modes of YBCO/STO/YBCO circular disk resonators
- 1996
-
In: IEEE Transactions on Microwave Theory and Techniques. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9480 .- 1557-9670. ; 44:10, s. 1738 - 1741
-
Journal article (peer-reviewed)abstract
- Lower order modes in a single crystal strontium titanate (STO) circular disk resonator are studied experimentally. Superconducting epitaxial YBCO films form the parallel-plates of the resonator. Due to the extremely high dielectric constant of STO, the electric fields are concentrated between the plates, while there is a substantial magnetic fringing field which affects both the resonant frequencies, Q-factors, and tunability of all modes, especially the TM110 and TM210
|
|
| 17. |
|
|
| 18. |
- Kuylenstierna, Dan, 1976, et al.
(author)
-
BROADBAND SMALL SIZE BALUN BUILT WITH LUMPED COMPONENTS
- 2003
-
In: Gigahertz 2003 Proceedings. - 0780383311
-
Conference paper (other academic/artistic)abstract
- This paper reports on a small size broadband lumped element balun suitable for integration in MMICs. The design is an extension of the well known lattice balun, which independent of frequency has 180 degrees phase difference between the output ports, but suffers from a narrow amplitude bandwidth. It is shown how the amplitude bandwidth of the lattice balun may be improved by replacing inductors with low-pass T-sections, and the capacitors with high-pass T-sections. Scalable closed-form design equations for various bandwidths are derived. To validate the concept a prototype operating at 1 GHz has been fabricated with SMT chip components soldered on a PTFE laminate. It exhibits amplitude balance better than +or-0.25 dB and phase balance better than +or-8 degrees , over more than one octave bandwidth. The effective chip-area is 7*9 mm/sup 2/
|
|
| 19. |
|
|
| 20. |
- Kuylenstierna, Dan, 1976, et al.
(author)
-
Design of broad-band lumped-element baluns with inherent impedance transformation
- 2004
-
In: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480 .- 1557-9670. ; 52:12, s. 2739-45
-
Journal article (peer-reviewed)abstract
- This paper reports on a novel lumped balun topology, the second-order lattice balun, with broad-band performance. The design is based on synthetic transmission lines operating as impedance transformers. The characteristic impedance of the synthetic transmission lines may be chosen to obtain inherent impedance transformation. An analytical investigation results in closed formulas for optimum performance over a given bandwidth. It is shown that it is possible to design for equal ripple in amplitude balance and input reflection coefficient. The phase balance is theoretically perfect over the entire bandwidth. The concept is experimentally validated by a 1-GHz prototype fabricated with surface mounted chip components. It exhibits an amplitude balance better than 0.5 dB and a phase balance better than +or-8 degrees over an octave bandwidth. The effective area of the prototype is 7 * 9 mm/sup 2/
|
|
| 21. |
- Kuylenstierna, Dan, 1976, et al.
(author)
-
Design of broadband lumped element baluns
- 2004
-
In: 2004 IEEE MTT-S International Microwave Symposium Digest, 6-11 June 2004. - 0780383311 ; Vol.2, s. 899-902
-
Conference paper (peer-reviewed)abstract
- This paper reports on a small size broadband lumped element balun suitable for integration in MMICs. The design is an extension of the well known lattice balun, which independent of frequency has 180 degrees phase difference between the output ports, but suffers from a narrow amplitude bandwidth. It is shown how the amplitude bandwidth of the lattice balun may be improved by replacing inductors with low-pass T-sections, and the capacitors with high-pass T-sections. Scalable closed-form design equations for various bandwidths are derived. To validate the concept a prototype operating at 1 GHz has been fabricated with SMT chip components soldered on a PTFE laminate. It exhibits amplitude balance better than +or-0.25 dB and phase balance better than +or-8 degrees , over more than one octave bandwidth. The effective chip-area is 7*9 mm/sup 2/
|
|
| 22. |
- Kuylenstierna, Dan, 1976, et al.
(author)
-
Ferroelectrically tuneable delay lines
- 2004
-
In: Conference Proceedings. 34th European Microwave Conference, 12-14 Oct. 2004. ; vol.1, s. 157-60
-
Conference paper (peer-reviewed)abstract
- Ferroelectric (Ba/sub 0.25/Sr/sub 0.75/TiO/sub 3/) varactors are integrated on a Si substrate to form compact wideband true-time tuneable delay lines. The delay-line design is of the lumped element approach, implemented as a synthetic coplanar strip (CPS) line. The physical size of the delay lines is 2.0*0.33 mm/sup 2/. Up to 20 GHz, the measured delay time per unit length is approximately constant equal to 40 ps/mm (corresponding to a slow wave factor of 12) and the losses are about 0.049 dB/ps. The tuneability under 30 V DC-bias is 10%
|
|
| 23. |
|
|
| 24. |
- Kuylenstierna, Dan, 1976, et al.
(author)
-
Ultrawide-band tunable true-time delay lines using ferroelectric varactors
- 2005
-
In: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480 .- 1557-9670. ; 53:6, pt.2, s. 2164-70
-
Journal article (peer-reviewed)abstract
- This paper reports on compact tunable true-time delay lines based on ferroelectric (Ba/sub 0.25/Sr/sub 0.75/TiO/sub 3/) varactors integrated on high-resistivity silicon. The delay lines are based on lumped elements, physically implemented as synthetic coplanar-strip lines. An approximate analytical design procedure, exactly valid for omega to 0, is proposed. The physical size of the fabricated delay lines is 2.0*0.33 mm/sup 2/, including bias pads. Measurements are performed from room temperature (RT) down to 80 K. The measurements reveal ultrawide-band characteristics for both group delay and insertion loss. At RT, the absolute group delay is tau /sub delta /(RT, 0 V) approximately=70 ps with tunability of 20% under 20-V dc bias, the insertion less than 3.5 dB, and the reflection loss better than 12 dB below 20 GHz. At 145 K, the absolute group delay is increased to tau /sub delta /(145 K, 0 V) approximately=100 ps with a tunability of 50% under 20-V applied bias. At 7 GHz, the insertion loss is 3 dB, resulting in figures-of-merit of 0.03 dB/ps and 50 ps/mm. The leakage current at RT is less than 0.1 mu A
|
|
| 25. |
- Nilsson, Emil, et al.
(author)
-
A new CMOS radio for low power RFID applications
- 2010
-
In: Proceedings of 2010 IEEE International Conference on RFID-Technology and Applications : June 17-19, 2010 : Dong Fang Hotel, Guangzhou, China.. - Piscataway, N.J. : IEEE Press. - 9781424467006 ; , s. 106-111
-
Conference paper (peer-reviewed)abstract
- A novel radio receiver circuit, functioning as a tuned active, detecting antenna, is described. The receiver is suggested to be part of a new radio system with the potential of competing with the range capability of active RFID-tags and, through its low power and long lifetime, with passive RFID-tags. The circuit is outlined and the functionality is verified by simulations and measurements.A 24 MHz discrete prototype showed better than -70 dBm sensitivity and 5 kHz bandwidth, with a power consumption of 102 μW. Simulations of a monolithic implementation were performed at 2.5 GHz. The detector is modeled by using 180 nm CMOS transistors. In simulations the power consumption for the detector is below 125 μW at a sensitivity of -83 dBm and a bandwidth of 9 MHz.Our conclusion is that this novel simple circuit architecture is well suited for monolithic implementation of a low power transceiver.
|
|
| 26. |
- Rafique, Raihan, 1978, et al.
(author)
-
Miniaturization of superconducting passive filters for on-chip applications
- 2007
-
In: 11th International Superconducting Electronics Conference, Washington DC, USA, June 10-14, 2007.. ; 11, s. P-V09
-
Conference paper (other academic/artistic)abstract
- We present techniques to miniaturize superconducting ultra narrowband filters for on-chip applications. The filters are designed for 2 GHz, 5 GHz and 10 GHz operating frequencies. The expected bandwidths of the designed filters are 2-20 MHz. The designs are of 7 stages Chebyshev filters having maximum passband ripples of 0.5 dB. On-chip filters are particularly interesting as they are applicable for monolithic design with the RSFQ circuit aiming qubit applications. One of the designs is a quasi-lumped filter where the effective wave propagation constant has been increased by the addition of lumped components to the superconducting microstrip line (SMSL). Additionally, this design provides the optimum width of an SMSL without violating design rules. The other design consists of distributed and lumped components. The area of the filter is in the range of 1-2 square mm. We present the filter topologies and corresponding experimental results for the frequency response of these on-chip filters designed for Hypres 4.5 kA/cm2 fabrication process.
|
|
| 27. |
- Rafique, Raihan, 1978, et al.
(author)
-
Miniaturized superconducting microwave filters
- 2008
-
In: Superconducting Science and technology, press.
-
Journal article (peer-reviewed)abstract
- In this paper we present methods for miniaturization of superconducting filters. We consider two designs of 7th order bandpass Chebyshev filters based on lumped elements and a novel quasi-lumped element resonators. In both designs the area of the filters, with a central frequency of 2-5 GHz, is less than 1.2 mm2. Such small filters can be readily integrated on one board for multi-channel microwave control of superconducting qubits. The filters have been experimentally tested and the results are compared with simulations. The miniaturization resulted in parasitic coupling between resonators and within eachresonator that affected primarily stopband and bandwidth increase. The severity of the error depends on the design in particular, and was less prawn when groundplane was used under the inductances of the resonators. The best performance was reached for the quasi-lumped filter with central frequency of 4.5 GHz, quality factor of 100 and 28 dB stopband.
|
|
| 28. |
- Rafique, Raihan, 1978, et al.
(author)
-
Niobium Tunable Microwave Filter
- 2009
-
In: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480 .- 1557-9670. ; 57:5, s. 1173-1179
-
Journal article (peer-reviewed)abstract
- A superconductor bandpass filter with tunable centralfrequency in the range of 2.1–3.5 GHz has been implementedusing Superconducting Quantum Interference Devices (SQUID).The filter is designed as two pi–network resonators connected by a transmission line. Both resonators have a SQUID inductor with a tuning range of 65–200 pH, controlled by DC current magnetically coupled to the SQUIDs. Over a frequency tunability of 40% from 3.5 to 2.1 GHz, the filter has a corresponding fractional bandwidth of 35% to 27% and a mid-band insertion loss of 0.5–3.0 dB. Due to the presence of active elements, the tunability of the filter depends on the power of the microwave signal. A maximum power of -52dBm corresponds to a frequency tuning range of 15%. Spectral measurements by controlling the central frequency of the filter with variable pulse-width shows that the filter can be tuned at a rate of 120 GHz per us.
|
|
| 29. |
|
|
| 30. |
- Rafique, Raihan, 1978, et al.
(author)
-
Tunable Impedance Matching Network
- 2008
-
In: GigaHertz Symposium, March, 2008. ; , s. 15-
-
Conference paper (peer-reviewed)abstract
- We present superconducting SQUID based tunableimpedance matching networks designed for highly miniaturized filters. The performance of miniaturized filters is very sensitive to parasitic and fabrication related spread. The presented experimental results show that using tunable impedance matching networks, the degraded performances of these types of filters isimproved.
|
|
| 31. |
- Zeng, Xuezhi, 1980, et al.
(author)
-
Accuracy evaluation of time domain measurement systems for microwave tomography
- 2009
-
In: IEEE MTT-S International Microwave Symposium Digest. - 0149-645X. - 9781424428045 ; , s. 1441-1444
-
Conference paper (peer-reviewed)abstract
- The measurement accuracy of time domain systemsfor microwave tomography are evaluated through system levelsimulations and compared with that of a network analyzerbased frequency domain system. In the analysis, both a timedomain ultra-wideband (UWB) impulse and multiband systemarchitectures are considered. It is shown that the measurementerror of the time domain systems mainly comes from analogto digital (A/D) conversion. For a simple comparison case, therelative measurement error involved in an estimated objectresponse signal from the time domain UWB impulse system andUWB multiband system measurements are around three timesand ten times higher than that from frequency domain system.
|
|
| 32. |
- Zeng, Xuezhi, 1980, et al.
(author)
-
Accuracy Evaluation of Ultrawideband Time Domain Systems for Microwave Imaging
- 2011
-
In: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 59:11, s. 4279-4285
-
Journal article (peer-reviewed)abstract
- We perform a theoretical analysis of the measurement accuracy of ultrawideband time domain systems. The theory is tested on a specific ultrawideband system and the analytical estimates of measurement uncertainty are in good agreements with those obtained by means of simulations. The influence of the antennas and propagation effects on the measurement accuracy of time domain near field microwave imaging systems is discussed. As an interesting application, the required measurement accuracy for a breast cancer detection system is estimated by studying the effect of noise on the image reconstructions. The results suggest that the effects of measurement errors on the reconstructed images are small when the amplitude uncertainty and phase uncertainty of measured data are less than 1.5 dB and 15 degrees, respectively.
|
|
| 33. |
- Zeng, Xuezhi, 1980, et al.
(author)
-
Accuracy investigation of an ultra-wideband time domain microwave imaging system
- 2011
-
In: Proceedings of the 5th European Conference on Antennas and Propagation, EUCAP 2011. Rome, 11-15 April 2011. - 9788882020743 ; , s. 1928-1932
-
Conference paper (peer-reviewed)abstract
- We investigate the measurement accuracy of an ultra-wideband time domain microwave tomography system. A phantom is imaged by means of the system and the reconstructed images are compared to those obtained with an ultra-wideband frequency domain system. The results suggest that the permittivity reconstructions obtained by means of the time domain and the frequency domain systems are very similar to each other, but the conductivity profile reconstructed from time domain measurements presents worse quality than that obtained from frequency domain measurements.
|
|
| 34. |
- Zeng, Xuezhi, 1980, et al.
(author)
-
An ultrawideband microwave medical diagnostic system: Design considerations and system performance
- 2012
-
In: Proceedings of 6th European Conference on Antennas and Propagation, EuCAP 2012. Prague, 26-30 March 2012. - 9781457709180 ; , s. 3664-3668
-
Conference paper (peer-reviewed)abstract
- We discuss several issues in the design of an ultra-wideband microwave system dedicated to medical diagnostics. Based on the discussion, a FPGA-based time domain microwave diagnostic system is proposed. The noise sources of the system are identified and the system noise performance is analyzed. As an example, a 2-D antenna system is considered and the measurement signal to noise ratios are evaluated.
|
|
| 35. |
|
|
| 36. |
- Zeng, Xuezhi, 1980, et al.
(author)
-
Design and Performance Evaluation of a Time Domain Microwave Imaging System
- 2013
-
In: International Journal of Microwave Science and Technology. - : Hindawi Limited. - 1687-5826 .- 1687-5834. ; 2013, s. Art. no. 735692-
-
Journal article (peer-reviewed)abstract
- We design a time domain microwave system dedicated to medical imaging. The measurement accuracy of the system, that is, signal-to-noise ratio, due to voltage noise and timing noise, is evaluated. Particularly, the effect of coupling media on the measurement accuracy is investigated both numerically and experimentally. The results suggest that the use of suitable coupling media betters the measurement accuracy in the frequency range of interest. A signal-to-noise ratio higher than 30 dB is achievable in the range of 500 MHz to 3 GHz when the effective sampling rate is 50 Gsa/s. It is also indicated that the effect of the timing jitter on the strongest received signal is comparable to that of the voltage noise.
|
|
| 37. |
- Zeng, Xuezhi, 1980, et al.
(author)
-
Development of a Time Domain Microwave System for Medical Diagnostics
- 2014
-
In: IEEE Transactions on Instrumentation and Measurement. - 1557-9662 .- 0018-9456. ; 63:12, s. 2931-2939
-
Journal article (peer-reviewed)abstract
- In this paper, a time-domain system dedicated to medical diagnostics has been designed, a prototype has been built and its performance has been evaluated. Measurements show that the system has a 3-dB bandwith of about 3.5 GHz and a signal to noise ratio over 40 dB in the frequency range about 800 MHz to 3.8 GHz. The system has been used to perform a microwave tomographic image reconstruction test. The same target was reconstructed based on data measured with a network analyzer. A comparison between the images shows very small differences, and proves the functionality of the time domain system.
|
|
| 38. |
- Zeng, Xuezhi, 1980, et al.
(author)
-
Experimental Investigation of the Accuracy of an Ultrawideband Time-Domain Microwave-Tomographic System
- 2011
-
In: IEEE Transactions on Instrumentation and Measurement. - 1557-9662 .- 0018-9456. ; 60:12, s. 3939-3949
-
Journal article (peer-reviewed)abstract
- The measurement accuracy of an ultrawideband (UWB) time-domain microwave-tomographic system is investigated. In order to make an assessment of the random variation of the measurements, the measurement repeatability of the system is evaluated by comparison with an UWB frequency-domain system. A phantom is imaged with the time-domain microwave-tomographic system, and the reconstructed images are compared with those obtained by using the frequency-domain system. The results suggest that with the averaging tens of measurements, the time-domain system can achieve the same level of measurement repeatability as that of the frequency-domain system in the interesting frequency range of microwave tomography. The imaging results, however, indicate that the phantom reconstruction does not require such high measurement accuracy. The permittivity profile of the phantom reconstructed from the nonaveraging time-domain measurements is very similar with that obtained by means of the frequency-domain system.
|
|
| 39. |
|
|
| 40. |
- Zhang, Bing, 1982, et al.
(author)
-
Attempt of the Metallic 3D Printing Technology for Millimeter-Wave Antenna Implementations
- 2016
-
In: Asia-Pacific Microwave Conference, APMC 2015. ; 2
-
Conference paper (peer-reviewed)abstract
- 3D metallic printing technology is attempted to implement millimeter-wave (mmWave) antennas. Based on laser beam melting (LBM) technology, the cost and turnaround time of metallic horn antenna fabrication is effectively reduced compared with traditional milling and injection moulding. A conical and a pyramidal horn antenna are printed in 316L stainless steel, both of which demonstrate satisfactory performance compared with simulation, as well as comparable performance with commercial horn antennas. Surface roughness of the printed horn antennas are measured and analyzed, showing improvement upon former designs. The 3D printing technology proves its great potential for further exploration.
|
|
| 41. |
- Zhang, Bing, 1982, et al.
(author)
-
Metallic 3-D Printed Antennas for Millimeter- and Submillimeter Wave Applications
- 2016
-
In: IEEE Transactions on Terahertz Science and Technology. - : Institute of Electrical and Electronics Engineers (IEEE). - 2156-342X .- 2156-3446. ; 6:4, s. 592-600
-
Journal article (peer-reviewed)abstract
- This paper presents a study to use the metallic three dimensional (3-D) printing technology for antenna implementations up to 325 GHz. Two different printing technologies and materials are used, namely binder jetting/sintering on 316L stainless steel and selective laser melting (SLM) on Cu-15Sn. Phases, microstructure, and surface roughness are investigated on different materials. Balancing between the cost and performance, the manually polished Cu-15Sn is selected to develop a series of conical horn antennas at the E-(60-90 GHz), D-(110-170 GHz), and H-band (220-325 GHz). Good agreement is observed between the simulated and measured antenna performance. The antennas' impedance bandwidth (vertical bar S-11 vertical bar < -20 dB) cover the whole operational band, with in-band gain of > 22.5, > 22, and > 21.5 dBi for the E-, D-, and H-band antennas, respectively. Compared with the traditional injection molding and micromachining for metallic horn antenna implementation, the 3-D printed metallic horn antenna features environmental friendliness, low cost, and short turn-around time. Compared with the nonmetallic 3-D printed antennas, they feature process simplicity and mechanical robustness. It proves great potential of the metallic 3-D printing technology for both industrial mass production and prototyping.
|
|
