Adam Abramowicz - Academia.edu (original) (raw)

Papers by Adam Abramowicz

arXiv (Cornell University), 2020

In the present work we study the growth by pulsed laser deposition of YBa$_2$Cu$_3$O$_{7-\delta}$... more In the present work we study the growth by pulsed laser deposition of YBa$_2$Cu$_3$O$_{7-\delta}$ (YBCO) films on the r-cut sapphire substrates. To improve the matching of the lattice parameters between the substrate and the film we use CeO$_{2}$ buffer layer, recrystallized prior to the deposition of YBCO. The optimal thickness and temperature of recrystallization of the buffer layer is first determined using atomic force microscopy (AFM) and X-ray diffraction. Next, we use the AFM to examine the dependence of YBCO film roughness on the film thickness, and we study the homogeneity of magnetic flux penetration into the films by magneto-optical imaging. We find that the superconducting critical temperature and critical current density of these films are very similar to those of YBCO films grown on well-matched substrates. It appears that the microstructure of YBCO films is affected by structural defects in the buffer layer as well as variations in oxygen deficiency, which results in high values of critical current density suitable for application.

12th International Conference on Microwaves and Radar. MIKON-98. Conference Proceedings (IEEE Cat. No.98EX195), Nov 27, 2002

2022 24th International Microwave and Radar Conference (MIKON), Sep 12, 2022

This paper presents an analog RF front-end for FMCW radars, designed as a single PCB module, oper... more This paper presents an analog RF front-end for FMCW radars, designed as a single PCB module, operating in C-band (5-6 GHz) frequencies. The presented RF front-end part is characterized by its relatively small size, small weight and low power consumption. It is possible to use it in different radar applications. In this paper the design process with both laboratory and outdoor measurement results of the manufactured module are presented. For the outdoor measurement the designed RF front-end part was tested as a compact RF module for SAR radars. The results of these tests are also shown in this paper.

2022 24th International Microwave and Radar Conference (MIKON), Sep 12, 2022

2018 22nd International Microwave and Radar Conference (MIKON), 2018

The presented high directivity narrowband couplers consist of two transmission lines coupled at t... more The presented high directivity narrowband couplers consist of two transmission lines coupled at two points with capacitances realized as metal patches placed at different layers of the PCB board. The main lines are basically uncoupled. The couplers can be realized in different multilayer stack-ups thus can be easily integrated into PCB circuits. The coupling value can be set from 3 dB to 30 dB. The directivity of the couplers is better than 30 dB in the narrow relative bandwidth of 2%. The match is better than 25 dB. The size of the couplers is much lower than the typical quarter wave length.

2015 IEEE International Conference on Microwaves, Communications, Antennas and Electronic Systems (COMCAS), 2015

The paper presents methodology for designing wideband and ultra-wideband filters with electric (c... more The paper presents methodology for designing wideband and ultra-wideband filters with electric (capacitive) or magnetic (inductive) direct couplings based on closed-form formulas. For given filter specifications (required frequency characteristic, filter center frequency, bandwidth) the method gives filter parameters as a set of resonant frequencies, coupling factors, external quality factors and characteristic impedances of the filter resonators. The method is based on analysis of circuit models of filters with only-electric and only-magnetic direct couplings. Numerical experiments of the circuit models allowed to study properties of such filters and to build effective design method. In this paper method for designing 5th order filters is described in details. High accuracy of the presented method is also addressed.

2015 Signal Processing Symposium (SPSympo), 2015

A voltage tunable bandpass filter is presented. The filter is realized in microstrip technology u... more A voltage tunable bandpass filter is presented. The filter is realized in microstrip technology using two stepped-impedance resonators. The voltage tuning is provided by means of varactor diodes. The filter has fixed absolute bandwidth of 30 MHz in the frequency range from 375 MHz to 915 MHz. The insertion loss is lower than 5 dB and return loss better than 17 dB in the full tuning range. The out of band attenuation is better than 40 dB at frequencies below the passband and better than 50 dB at frequencies above the passband. The first spurious modes are observed at 6 GHz. Moreover the time delay in the full tuning range changes by 30% only. The filter is thermally stable. It has 1 dB compression point of 10 dBm and third-order intercept point of 21 dBm.

2017 Signal Processing Symposium (SPSympo)

This paper describes the investigation on relative bandwidth, frequency range and thermal propert... more This paper describes the investigation on relative bandwidth, frequency range and thermal properties of the high directivity planar couplers realized in microstrip line technology. The basic idea is that coupling structure is attached to two transmission lines at two points only. The coupling structure is realized using SMD capacitances and inductances soldered to the microstrip lines. Frequency limit for successful realization of proposed coupled depends mainly on SMD elements values. The relative bandwidth can be extended by modified coupling structure. Several couplers with different couplings have been designed for 1.3 GHz band and 3 GHz band. The proposed couplers are wideband for weak couplings. Couplers are planar, compact and easy to realize.

2017 International Conference on Electromagnetics in Advanced Applications (ICEAA), 2017

In the paper the direct solution of Maxwell equations in the rectangular waveguide filled with di... more In the paper the direct solution of Maxwell equations in the rectangular waveguide filled with dielectric layers is presented. Each dielectric layer has different permittivity and losses. Metal losses in the bottom and top waveguide walls are taken into account. The two types of modes are found, which have five field components each. These modes are TEy and TMy, because they have only Hy component along Y axis and only Ey component along Y axis respectively. The modes propagate along z axis. The solution of the problem has been based on the know results presented for the multilayered radial waveguide. The developed computer program computes the propagation constants and field distributions for any mode subscripts and up to 25 lossy dielectric layers.

2018 International Conference on Signals and Electronic Systems (ICSES), 2018

This paper describes the design method for high directivity couplers. The couplers consist of two... more This paper describes the design method for high directivity couplers. The couplers consist of two electromagnetically uncoupled transmission lines and lumped capacitors connecting the lines at two points only. The derivation of design formulas is given. The analyzed couplers are related to the known lumped element couplers with capacitive coupling. The comparison of the lumped element coupler with the high directivity coupler leads to a set of exact design formulas.

2018 22nd International Microwave and Radar Conference (MIKON), 2018

This paper presents three realization of extremely narrowband dielectric resonator filters. High ... more This paper presents three realization of extremely narrowband dielectric resonator filters. High quality filters are realized as two-pole filters with relative bandwidths as low as 0.028% and 0.0054%. The filters are realized in aluminum housings using dielectric resonators of permittivity 37 and temperature coefficient +3 ppm/°C. The filters demonstrate good thermal stability better than 3 ppm/°C. High power version of the filter is capable to handle 100 Watts of input power.

The Fourteenth Marcel Grossmann Meeting, 2017

The presented high directivity narrowband multi-layer couplers consist of two transmission lines ... more The presented high directivity narrowband multi-layer couplers consist of two transmission lines located on different layers of PCB board and coupled through spatially small coupling structures. The main lines are coupled only at two points. The coupling value can be set from 3 dB to 30 dB. The couplers can be realized in different multilayer stack-ups thus can be easily integrated into variety of PCB circuits. The directivity of the couplers is better than 30 dB in the narrow relative bandwidth of 2 %. The matching is better than 25 dB.

Development of the LLRF system at ESS is coordinated by the Lund University, but part of it, LLRF... more Development of the LLRF system at ESS is coordinated by the Lund University, but part of it, LLRF systems for M-Beta and H-Beta sections, will be delivered within in-kind contribution from Poland. This document will describe the scope of work, work plan, and technical details of the selected components of the MBeta and H-Beta LLRF systems sections. Described contribution will be made by the Polish Electronic Group (PEG), a consortium of three scientific units. LLRF system for ESS will be made of both, commercially available components and components designed specially for this project, and those last ones will be presented and described here. Except the technical details, the organizational aspects, such as schedule, project management or quality control, will be presented as well. POLISH ELECTRONIC GROUP For the purpose of participation in ESS LLRF system development within polish in-kind contribution (IKC), a consortium of three polish research units has been established and calle...

The paper describes the design method and simulations results of high directivity planar directio... more The paper describes the design method and simulations results of high directivity planar directional couplers with impedance transformation between the main and the coupled ports. Presented couplers are realized in microstrip line technology. The basic idea is to allow for coupling between two different impedance transmission lines. The coupling is realized by lumped capacitors soldered at two ends of coupled lines section. The proposed directional couplers are narrowband and high directivity. Wide range of coupling factors is easy to achieve. The example structures presented in the paper have a few levels of coupling factors and have been designed for operating frequencies 1.3 GHz and 3.0 GHz. The directivity of the couplers is better than 30 dB in the narrow bandwidth and the impedance matching is better than 25 dB at any port.

2020 23rd International Microwave and Radar Conference (MIKON), 2020

The European Spallation Source (ESS) is a next-generation neutron source, under construction in L... more The European Spallation Source (ESS) is a next-generation neutron source, under construction in Lund, Sweden. An important requirement for ESS is to assure a precise phase synchronization of LLRF and Beam Diagnostics systems. They are operating at frequencies of 352.21 MHz and 704.42 MHz. The phase stability along the machine is provided by the phase synchronization system. The main part of the system is a Phase Reference Line (PRL). It is an entirely passive system based on a single coaxial rigid line located in the tunnel, which distributes both reference frequencies. A source of the reference signals is a Master Oscillator (MO) located in the Klystron Gallery. High power amplifiers used at each frequency provide a power level of about +50 dBm. The output signals are combined in a custom made diplexer. The two-tone signal is distributed to the tunnel by a single 7/8" coaxial cable. Ambient temperature variations and humidity changes in the tunnel, STUB, and Klystron Gallery c...

2020 23rd International Microwave and Radar Conference (MIKON), 2020

In this paper an example of the high power diplexer for the phase reference line in proton accele... more In this paper an example of the high power diplexer for the phase reference line in proton accelerator is presented. The diplexer operates at frequency 352 MHz and 704 MHz. The output power level is 200 W. Additionally the requirements for the slope of the diplexer phase characteristic have been set at low level. The diplexer consists of two filters realized in the microstrip line technology. To improve the diplexer characteristics a special method has been used in the design. The inverters in the lower frequency passband filter have different electric lengths. The measurements show the low loss, high isolation of transmission bands and phase stable in the passbands thus confirm applied method.

2016 21st International Conference on Microwave, Radar and Wireless Communications (MIKON), 2016

We present results of equivalent-circuit modeling of center-conductor gap in coaxial connectors. ... more We present results of equivalent-circuit modeling of center-conductor gap in coaxial connectors. We perform broad-band full-wave electromagnetic simulations of the connector interface and then model their results with a simple equivalent circuit. We further show that the model parameters have simple physical interpretation. Our results can be used to improve the accuracy of millimeter-wave scattering-parameter measurements with small coaxial transmission lines.

IEEE Transactions on Microwave Theory and Techniques, 2018

We present an approach for first-order modeling of errors in vector-network-analyzer (VNA) measur... more We present an approach for first-order modeling of errors in vector-network-analyzer (VNA) measurements caused by the coaxial-connector interface. These errors result primarily from the presence of a gap in the inner conductor. Our approach relies on an approximate model of the connector interface that comprises an analytical equivalent-circuit for the inner conductor gap section and a behavioral scattering-parameter model for the socket-contact section. We verify this model using full-wave electromagnetic simulations for the 1.85, 2.4, 3.5 mm, and Type-N coaxial-connector interface for different inner conductor-gap widths. We further apply this model to asses first-order errors in VNA calibration introduced by the tolerance on the inner conductor-gap width. We show that the inner conductor-gap effect can be accounted for with a series inductance inserted at the inner conductor mating-plane while the effect of the socket contact can be lumped into the VNA calibration coefficients. We verify this error model experimentally by measuring a Type-N offset load with an adjustable inner conductor gap. We also demonstrate that including our error model in coaxial offsetshort definitions leads to improved consistency of a one-port VNA calibration with 3.5-mm coaxial offset-short standards. Our results can be used in the uncertainty analysis and accuracy enhancement of VNA scattering-parameter measurements.

arXiv (Cornell University), 2020

In the present work we study the growth by pulsed laser deposition of YBa$_2$Cu$_3$O$_{7-\delta}$... more In the present work we study the growth by pulsed laser deposition of YBa$_2$Cu$_3$O$_{7-\delta}$ (YBCO) films on the r-cut sapphire substrates. To improve the matching of the lattice parameters between the substrate and the film we use CeO$_{2}$ buffer layer, recrystallized prior to the deposition of YBCO. The optimal thickness and temperature of recrystallization of the buffer layer is first determined using atomic force microscopy (AFM) and X-ray diffraction. Next, we use the AFM to examine the dependence of YBCO film roughness on the film thickness, and we study the homogeneity of magnetic flux penetration into the films by magneto-optical imaging. We find that the superconducting critical temperature and critical current density of these films are very similar to those of YBCO films grown on well-matched substrates. It appears that the microstructure of YBCO films is affected by structural defects in the buffer layer as well as variations in oxygen deficiency, which results in high values of critical current density suitable for application.

12th International Conference on Microwaves and Radar. MIKON-98. Conference Proceedings (IEEE Cat. No.98EX195), Nov 27, 2002

2022 24th International Microwave and Radar Conference (MIKON), Sep 12, 2022

This paper presents an analog RF front-end for FMCW radars, designed as a single PCB module, oper... more This paper presents an analog RF front-end for FMCW radars, designed as a single PCB module, operating in C-band (5-6 GHz) frequencies. The presented RF front-end part is characterized by its relatively small size, small weight and low power consumption. It is possible to use it in different radar applications. In this paper the design process with both laboratory and outdoor measurement results of the manufactured module are presented. For the outdoor measurement the designed RF front-end part was tested as a compact RF module for SAR radars. The results of these tests are also shown in this paper.

2022 24th International Microwave and Radar Conference (MIKON), Sep 12, 2022

2018 22nd International Microwave and Radar Conference (MIKON), 2018

The presented high directivity narrowband couplers consist of two transmission lines coupled at t... more The presented high directivity narrowband couplers consist of two transmission lines coupled at two points with capacitances realized as metal patches placed at different layers of the PCB board. The main lines are basically uncoupled. The couplers can be realized in different multilayer stack-ups thus can be easily integrated into PCB circuits. The coupling value can be set from 3 dB to 30 dB. The directivity of the couplers is better than 30 dB in the narrow relative bandwidth of 2%. The match is better than 25 dB. The size of the couplers is much lower than the typical quarter wave length.

2015 IEEE International Conference on Microwaves, Communications, Antennas and Electronic Systems (COMCAS), 2015

The paper presents methodology for designing wideband and ultra-wideband filters with electric (c... more The paper presents methodology for designing wideband and ultra-wideband filters with electric (capacitive) or magnetic (inductive) direct couplings based on closed-form formulas. For given filter specifications (required frequency characteristic, filter center frequency, bandwidth) the method gives filter parameters as a set of resonant frequencies, coupling factors, external quality factors and characteristic impedances of the filter resonators. The method is based on analysis of circuit models of filters with only-electric and only-magnetic direct couplings. Numerical experiments of the circuit models allowed to study properties of such filters and to build effective design method. In this paper method for designing 5th order filters is described in details. High accuracy of the presented method is also addressed.

2015 Signal Processing Symposium (SPSympo), 2015

A voltage tunable bandpass filter is presented. The filter is realized in microstrip technology u... more A voltage tunable bandpass filter is presented. The filter is realized in microstrip technology using two stepped-impedance resonators. The voltage tuning is provided by means of varactor diodes. The filter has fixed absolute bandwidth of 30 MHz in the frequency range from 375 MHz to 915 MHz. The insertion loss is lower than 5 dB and return loss better than 17 dB in the full tuning range. The out of band attenuation is better than 40 dB at frequencies below the passband and better than 50 dB at frequencies above the passband. The first spurious modes are observed at 6 GHz. Moreover the time delay in the full tuning range changes by 30% only. The filter is thermally stable. It has 1 dB compression point of 10 dBm and third-order intercept point of 21 dBm.

2017 Signal Processing Symposium (SPSympo)

This paper describes the investigation on relative bandwidth, frequency range and thermal propert... more This paper describes the investigation on relative bandwidth, frequency range and thermal properties of the high directivity planar couplers realized in microstrip line technology. The basic idea is that coupling structure is attached to two transmission lines at two points only. The coupling structure is realized using SMD capacitances and inductances soldered to the microstrip lines. Frequency limit for successful realization of proposed coupled depends mainly on SMD elements values. The relative bandwidth can be extended by modified coupling structure. Several couplers with different couplings have been designed for 1.3 GHz band and 3 GHz band. The proposed couplers are wideband for weak couplings. Couplers are planar, compact and easy to realize.

2017 International Conference on Electromagnetics in Advanced Applications (ICEAA), 2017

In the paper the direct solution of Maxwell equations in the rectangular waveguide filled with di... more In the paper the direct solution of Maxwell equations in the rectangular waveguide filled with dielectric layers is presented. Each dielectric layer has different permittivity and losses. Metal losses in the bottom and top waveguide walls are taken into account. The two types of modes are found, which have five field components each. These modes are TEy and TMy, because they have only Hy component along Y axis and only Ey component along Y axis respectively. The modes propagate along z axis. The solution of the problem has been based on the know results presented for the multilayered radial waveguide. The developed computer program computes the propagation constants and field distributions for any mode subscripts and up to 25 lossy dielectric layers.

2018 International Conference on Signals and Electronic Systems (ICSES), 2018

This paper describes the design method for high directivity couplers. The couplers consist of two... more This paper describes the design method for high directivity couplers. The couplers consist of two electromagnetically uncoupled transmission lines and lumped capacitors connecting the lines at two points only. The derivation of design formulas is given. The analyzed couplers are related to the known lumped element couplers with capacitive coupling. The comparison of the lumped element coupler with the high directivity coupler leads to a set of exact design formulas.

2018 22nd International Microwave and Radar Conference (MIKON), 2018

This paper presents three realization of extremely narrowband dielectric resonator filters. High ... more This paper presents three realization of extremely narrowband dielectric resonator filters. High quality filters are realized as two-pole filters with relative bandwidths as low as 0.028% and 0.0054%. The filters are realized in aluminum housings using dielectric resonators of permittivity 37 and temperature coefficient +3 ppm/°C. The filters demonstrate good thermal stability better than 3 ppm/°C. High power version of the filter is capable to handle 100 Watts of input power.

The Fourteenth Marcel Grossmann Meeting, 2017

The presented high directivity narrowband multi-layer couplers consist of two transmission lines ... more The presented high directivity narrowband multi-layer couplers consist of two transmission lines located on different layers of PCB board and coupled through spatially small coupling structures. The main lines are coupled only at two points. The coupling value can be set from 3 dB to 30 dB. The couplers can be realized in different multilayer stack-ups thus can be easily integrated into variety of PCB circuits. The directivity of the couplers is better than 30 dB in the narrow relative bandwidth of 2 %. The matching is better than 25 dB.

Development of the LLRF system at ESS is coordinated by the Lund University, but part of it, LLRF... more Development of the LLRF system at ESS is coordinated by the Lund University, but part of it, LLRF systems for M-Beta and H-Beta sections, will be delivered within in-kind contribution from Poland. This document will describe the scope of work, work plan, and technical details of the selected components of the MBeta and H-Beta LLRF systems sections. Described contribution will be made by the Polish Electronic Group (PEG), a consortium of three scientific units. LLRF system for ESS will be made of both, commercially available components and components designed specially for this project, and those last ones will be presented and described here. Except the technical details, the organizational aspects, such as schedule, project management or quality control, will be presented as well. POLISH ELECTRONIC GROUP For the purpose of participation in ESS LLRF system development within polish in-kind contribution (IKC), a consortium of three polish research units has been established and calle...

The paper describes the design method and simulations results of high directivity planar directio... more The paper describes the design method and simulations results of high directivity planar directional couplers with impedance transformation between the main and the coupled ports. Presented couplers are realized in microstrip line technology. The basic idea is to allow for coupling between two different impedance transmission lines. The coupling is realized by lumped capacitors soldered at two ends of coupled lines section. The proposed directional couplers are narrowband and high directivity. Wide range of coupling factors is easy to achieve. The example structures presented in the paper have a few levels of coupling factors and have been designed for operating frequencies 1.3 GHz and 3.0 GHz. The directivity of the couplers is better than 30 dB in the narrow bandwidth and the impedance matching is better than 25 dB at any port.

2020 23rd International Microwave and Radar Conference (MIKON), 2020

The European Spallation Source (ESS) is a next-generation neutron source, under construction in L... more The European Spallation Source (ESS) is a next-generation neutron source, under construction in Lund, Sweden. An important requirement for ESS is to assure a precise phase synchronization of LLRF and Beam Diagnostics systems. They are operating at frequencies of 352.21 MHz and 704.42 MHz. The phase stability along the machine is provided by the phase synchronization system. The main part of the system is a Phase Reference Line (PRL). It is an entirely passive system based on a single coaxial rigid line located in the tunnel, which distributes both reference frequencies. A source of the reference signals is a Master Oscillator (MO) located in the Klystron Gallery. High power amplifiers used at each frequency provide a power level of about +50 dBm. The output signals are combined in a custom made diplexer. The two-tone signal is distributed to the tunnel by a single 7/8" coaxial cable. Ambient temperature variations and humidity changes in the tunnel, STUB, and Klystron Gallery c...

2020 23rd International Microwave and Radar Conference (MIKON), 2020

In this paper an example of the high power diplexer for the phase reference line in proton accele... more In this paper an example of the high power diplexer for the phase reference line in proton accelerator is presented. The diplexer operates at frequency 352 MHz and 704 MHz. The output power level is 200 W. Additionally the requirements for the slope of the diplexer phase characteristic have been set at low level. The diplexer consists of two filters realized in the microstrip line technology. To improve the diplexer characteristics a special method has been used in the design. The inverters in the lower frequency passband filter have different electric lengths. The measurements show the low loss, high isolation of transmission bands and phase stable in the passbands thus confirm applied method.

2016 21st International Conference on Microwave, Radar and Wireless Communications (MIKON), 2016

We present results of equivalent-circuit modeling of center-conductor gap in coaxial connectors. ... more We present results of equivalent-circuit modeling of center-conductor gap in coaxial connectors. We perform broad-band full-wave electromagnetic simulations of the connector interface and then model their results with a simple equivalent circuit. We further show that the model parameters have simple physical interpretation. Our results can be used to improve the accuracy of millimeter-wave scattering-parameter measurements with small coaxial transmission lines.

IEEE Transactions on Microwave Theory and Techniques, 2018

We present an approach for first-order modeling of errors in vector-network-analyzer (VNA) measur... more We present an approach for first-order modeling of errors in vector-network-analyzer (VNA) measurements caused by the coaxial-connector interface. These errors result primarily from the presence of a gap in the inner conductor. Our approach relies on an approximate model of the connector interface that comprises an analytical equivalent-circuit for the inner conductor gap section and a behavioral scattering-parameter model for the socket-contact section. We verify this model using full-wave electromagnetic simulations for the 1.85, 2.4, 3.5 mm, and Type-N coaxial-connector interface for different inner conductor-gap widths. We further apply this model to asses first-order errors in VNA calibration introduced by the tolerance on the inner conductor-gap width. We show that the inner conductor-gap effect can be accounted for with a series inductance inserted at the inner conductor mating-plane while the effect of the socket contact can be lumped into the VNA calibration coefficients. We verify this error model experimentally by measuring a Type-N offset load with an adjustable inner conductor gap. We also demonstrate that including our error model in coaxial offsetshort definitions leads to improved consistency of a one-port VNA calibration with 3.5-mm coaxial offset-short standards. Our results can be used in the uncertainty analysis and accuracy enhancement of VNA scattering-parameter measurements.