| 1. |
- Carlsson, Erik F., 1968, et al.
(författare)
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Arrangement and method relating to filtering of signals
- 2000
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Patent (övrigt vetenskapligt/konstnärligt)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
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| 2. |
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| 3. |
- Gevorgian, Spartak, 1948, et al.
(författare)
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Lower order modes of YBCO/STO/YBCO circular disk resonators
- 1996
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Ingår i: IEEE Transactions on Microwave Theory and Techniques. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9480 .- 1557-9670. ; 44:10, s. 1738 - 1741
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Tidskriftsartikel (refereegranskat)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
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| 4. |
- Andersson, Ola, et al.
(författare)
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The impact of stay-at-home policies on individual welfare
- 2022
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Ingår i: Scandinavian Journal of Economics. - : Wiley. - 0347-0520 .- 1467-9442. ; 124:2, s. 340-362
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we perform a choice experiment assessing the impact of stay-at-home policies on individual welfare. We estimate the willingness to accept compensation (WTA) for restricting non-working hours in Sweden during the COVID-19 pandemic. The WTA for a one-month stay-at-home policy is about US$480 per person, or 9.1 percent of Sweden's monthly per capita GDP. Stricter lockdowns require disproportionately higher compensation than more lenient ones, indicating that strict policies are cost-effective only if they are much more successful in slowing the spread of the disease. Moreover, older people have a higher WTA of staying home than the rest of the population.
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| 5. |
- Carlsson, Erik F., 1968, et al.
(författare)
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Conformal mapping of the field and charge distributions in multilayered substrate CPWs
- 1999
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Ingår i: IEEE Transactions on Microwave Theory and Techniques. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9480 .- 1557-9670. ; 47:8, s. 1544 - 1552
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Tidskriftsartikel (refereegranskat)abstract
- Conformal mapping (CM) and partial capacitance techniques are used for analytical evaluation of charge/current and electric- and magnetic-field distributions in a multilayered substrate coplanar waveguide (CPW) in the quasi-TEM approximation. The results, compared with finite-element method simulations, show that the magnetic wall assumed at the dielectric-dielectric interfaces in CM is a good approximation for many practical cases. The method is applied to a CPW with a thin ferroelectric film used in tunable microwave devices
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| 6. |
- Carlsson, Erik F., 1968, et al.
(författare)
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Effect of enhanced current crowding in a CPW with a thin ferroelectric film
- 1997
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Ingår i: Electronics Letters. - : Institution of Engineering and Technology (IET). - 1350-911X .- 0013-5194. ; 33:2, s. 145-146
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Tidskriftsartikel (refereegranskat)abstract
- Enhanced current crowding is predicted at the edges of the conducting strips in thin ferroelectric film coplanar waveguides (CPWs). A minimum current crowding depth is expected, which depends on the CPW geometry and dielectric constant of the ferroelectric film. In practical CPW devices the enhanced current crowding can increase the conductor losses by up to four times. The current crowding depth may be smaller than the skin depth or London penetration depth (for high temperature superconducting CPW)
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| 7. |
- Carlsson, Erik F., 1968, et al.
(författare)
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Effects of package width on K-band high-temperature superconducting filters
- 1995
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Ingår i: Microwave and Optical Technology Letters. - : Wiley. - 1098-2760 .- 0895-2477. ; 10:6, s. 315-317
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Tidskriftsartikel (refereegranskat)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
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| 8. |
- Carlsson, Erik F., 1968, et al.
(författare)
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Electric field dependent microwave losses in KTaO3 single crystal with YBa2CU3O7-x electrodes
- 1999
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Ingår i: Ferroelectrics, Letters Section. - : Informa UK Limited. - 0731-5171 .- 1563-5228. ; 25:5-6, s. 141-152
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Tidskriftsartikel (refereegranskat)abstract
- We have measured the voltage dependence of the resonant frequency and the microwave losses for parallel-plate resonators based on single crystals KTaO3, with YBa2Cu3O7-x electrodes. The losses increase and the dielectric constant decrease monotonically with applied voltage. Both the dielectric constant and the losses show a hysteretic effect in the voltage dependence. The hysteretic effects may be explained by electric field assisted charge trapping both in the KTaO3, crystal and at the KTaO3/YBa2Cu3O7-x interfaces
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| 9. |
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| 10. |
- Carlsson, Erik F., 1968
(författare)
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High Temperature Superconducting and Tunable Ferroelectric Microwave Devices
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis addresses some applications of High Temperature Superconductors (HTS) and ferroelectric materials in tunable microwave devices and circuits. The work is divided into three main areas: i) modeling of multilayered structures including ferroelectric layers, ii) realization and characterization of tunable coplanar waveguides (CPW), capacitors and resonators based on ferroelectrics, and iii) an investigation of microstrip HTS K-band filters. The motivation for the work has been the increased demands on advanced microwave communication systems requiring miniaturized, low loss, and tunable microwave components. Closed form analytical models for multilayered CPW and coplanar strip (CPS) transmission lines, interdigital and straight gap planar capacitors are presented. The models are easy to implement in general purpose CAD-programs and may be used for synthesis and optimization of microwave devices in the quasi-static and quasi-TEM approximations. In this work the models are used for the design of CPWs lumped interdigital, and straight gap planar capacitors that include thin ferroelectric films. In addition the models are used for extraction of ferroelectric thin film parameters from measurements. The models show good agreement when compared with FEM simulations for a CPW. The models also predict an enhanced current crowding, dependent on geometry and dielectric constant of the ferroelectric film, at the conductor edges for a CPW on a substrate with a thin ferroelectric film. Tunable parallel-plate resonators based on bulk single crystal SrTiO3 and KTaO3 have been developed and studied. The resonators show a tuning of the resonant frequency exceeding 50 % from an applied bias electric field. The losses however increased monotonically with the applied electric field, and in the case of KTaO3, exhibited strong hysteresis. Tunability and losses for thin film ferroelectric planar capacitors and phase-shifters based on CPWs have been investigated for different geometries and ferroelectric thin film materials. A phase shift of 130 degrees per dB loss was obtained at 20 K and 20 GHz along a 3 mm long CPW. Narrow-band 18 GHz Chebyshev filters made of end- or side-coupled HTS microstrip line sections have also been developed. The influence of package related effects, such as substrate or package modes, on the filter performance is studied. K-band YBa2Cu3O7-.delta. (YBCO) based filters are shown to have better performance than identical Cu filters below 80 K with an insertion loss of 0.9 dB at 18 GHz and 77 K. This thesis also presents the development and operation of a cryogenic microwave probe station, for characterization of microwave devices operating between 20 K and room temperature and at frequencies up to 40 GHz.
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| 11. |
- Carlsson, Erik F., 1968, et al.
(författare)
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Parallel plate microwave devices having tapered current interrupting slots
- 2002
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Patent (övrigt vetenskapligt/konstnärligt)abstract
- A microwave device includes a number of parallel-plate resonators that include at least one dielectric substrate and first and second plates arranged on either side of the substrate. At least one of the plates of each of a number of the parallel-plate resonators includes a current interrupting device such that the current lines of at least one undesired mode are interrupted at their maxima to suppress the undesired mode. There is also described a method of interrupting undesired modes in a microwave device having a number of parallel-plate resonators
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| 12. |
- Chakalov, R, et al.
(författare)
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Fabrication and investigation of YBa2Cu3O7-delta/Ba0.05Sr0.95TiO3 thin film structures for voltage tunable devices
- 1998
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Ingår i: Physica C: Superconductivity and its Applications. - 0921-4534. ; 308:3-4, s. 279-288
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Tidskriftsartikel (refereegranskat)abstract
- High-temperature superconducting/ferroelectric thin film structures were deposited by laser ablation. Three types of voltage tunable devices were fabricated and investigated-trilayer capacitor, planar interdigital capacitor and coplanar waveguide. As ferroelectric the solid solution BaxSr1-xTiO3 was chosen with barium content x = 0.05 because its Curie temperature is close to the liquid nitrogen boiling point (77 K). Temperature and voltage dependences of the Ba0.05Sr0.95TiO3 dielectric constant epsilon(r,BSTO) were studied. High epsilon(r,BSTO) values were determined-up to 3000 at 75 K, 20 GHz and zero de bias. Efficient voltage tunability was demonstrated (up to 40%) at loss level tan delta=0.01-0.1. Compact YBa2Cu3O7-delta/Ba0.05Sr0.95TiO3 coplanar waveguide with as narrow gap as 18 mu m was tested as electrically tunable phase-shifter and field-induced phase shifts of more than 180 degrees were obtained by 35 V de bias at 20 GHz. This improvement was attained by proper choice of the ferroelectric material, accomplished epitaxial growth of the films and decrease of the specific dimensions. (C) 1998 Published by Elsevier Science B.V. All rights reserved.
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| 13. |
- Gevorgian, Spartak, 1948, et al.
(författare)
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Effects of degraded edges in strips of high‐temperature superconducting films at microwave frequencies
- 1995
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 67, s. 1615-
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Tidskriftsartikel (refereegranskat)abstract
- A simple model is proposed to analyzemicrowave properties of thin superconducting strips with degraded edge regions. A high resistance edge is assumed in the superconducting strip. It is shown that with increased temperature more current will flow inside the superconducting strip away from the damaged edge resulting in a reduction of effective surfaceresistance.
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| 14. |
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| 15. |
- Gevorgian, Spartak, 1948, et al.
(författare)
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HTS/ferroelectric devices for microwave applications
- 1997
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Ingår i: IEEE Transactions on Applied Superconductivity. - : Institute of Electrical and Electronics Engineers (IEEE). - 1558-2515 .- 1051-8223. ; 7:2, s. 2458 - 2461
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Tidskriftsartikel (refereegranskat)abstract
- High Temperature Superconducting (HTS, e.g. YBCO) microwave devices based on bulk or thin film ferroelectrics (e.g. Strontium Titanate-STO) are studied theoretically and experimentally. YBCO/STO/YBCO parallel-plate resonators and based on bulk single crystal STO are for electrically tunable high power filters, phase shifters and other devices in the frequency band 0.5-2.0 GHz of advanced microwave communication systems. Thin film YBCO/STO Inter-digital Capacitors (IDC), Coplanar Waveguides (CPW) phase shifters/delay lines are also designed and studied experimentally for low microwave power applications. Modelling problems of these devices and microwave losses in ferroelectrics are also discussed
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| 16. |
- Gevorgian, Spartak, 1948, et al.
(författare)
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Modelling of thin-film HTS/ferroelectric interdigital capacitors
- 1996
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Ingår i: IEE Proceedings: Microwaves, Antennas and Propagation. - : Institution of Engineering and Technology (IET). - 1350-2417 .- 1359-706X. ; 143:5, s. 397 - 401
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Tidskriftsartikel (refereegranskat)abstract
- The model of the interdigital capacitor (IDC) has been used for monitoring and analysing the dielectric properties of thin ferroelectric films. The dielectric properties of the film are correlated to its crystalline structure using a simple model of STO. The results of the analysis may be used for optimisation of growth and annealing processes of the films and reducing the effects of the electrode ferroelectric interface. The model can be used to optimise the design of IDCs in the sense of minimum losses and maximum controllability by selecting finger width and gapwidth of the IDC. Further improvement of the model suggests a comprehensive study of all possible mechanisms affecting the dielectric constant and the losses of STO films
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| 17. |
- Wikborg, E., et al.
(författare)
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Arrangement and method relating to coupling of signals to/from microwave devices
- 2001
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Patent (övrigt vetenskapligt/konstnärligt)abstract
- An arrangement for coupling electro magnetic waves, particularly microwaves, into and/or out of a device which includes a dielectric resonator having a non-linear dielectric substrate with a high dielectric constant and a coupling loop. The dimensions of the resonator and the coupling loop are related to the resonant frequency of the resonator. The coupling loop is so arranged in relation to the resonator that the magnetic field lines around the coupling loop match the internal film distribution of at least one mode, which has been selected to be excited, so that only that mode is excited. Coupling is provided only for this mode. The length of the coupling loop is comparable to or larger that the dimensions of the resonator.
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