Слави Баев, Боян Хаджистамов, Пламен Данков.� Лещи на Лунебърг като комуникационни антени Статият... more Слави Баев, Боян Хаджистамов, Пламен Данков.� Лещи на Лунебърг като комуникационни антени Статията се отнася за принципите за моделиране и симулация с ���симулатори на ���симулатори на ��симулатори на �симулатори на симулатори на добре познатите лещи на Люнебърг, използвани като комуникационни антенни устрой� ства. разгледани са модели на сферични, полусферични и цилиндрични многослойни лещи. резутатите показват ефективността на предложената симулационна процедура за изследване на фокусиращия ефект и антенните параметри на тези обемни излъчващи структури.
The measurement of the dielectric constant and loss tangent anisotropy of the planar RF substrate... more The measurement of the dielectric constant and loss tangent anisotropy of the planar RF substrates by the two-resonator method is considered in this paper. The principles of the separate determination of these parameters parallel and perpendicular to the substrate surface is discussed by three pairs of cavity measurement resonators, based on cylinder, reentrant, split cylinder and split post dielectric resonators. Examples of the measured anisotropy of known materials are presented.
The image guide (IG) has been traditionally considered as a perspective for millimeter wavelength... more The image guide (IG) has been traditionally considered as a perspective for millimeter wavelengths. The transition between the standard metal rectangular waveguide (SMRW) and the IG usually exists in every experimental setup involving the IG. Here we have examined experimentally using electric probes the distribution of the electric field components at a double SMRW -IG transition, comprising a dielectric core symmetrically tapered in the H-plane. After that, we have simulated this transition as well as some other transitions using the finite element method (FEM).
The paper considers several spread internal EMC problems, which take place in some microwave pass... more The paper considers several spread internal EMC problems, which take place in some microwave passive nonantenna devices -parasitic radiation, "high-altitude" fields, crosstalk, grounding inefficiency, etc. Near-field scanning combined with electromagnetic simulations have been used for their prediction and detection. Several design rules have been discussed to avoid these problems in the multi-layer antenna arrays up to Ka band.
High-performance measuring multi-port 3-level fixture for active device characterization in the K... more High-performance measuring multi-port 3-level fixture for active device characterization in the Ku-band is described in this paper. It is a low-cost alternative of the expensive microwave "on-wafer" measurements with CPW probes. The method of modeling of the separate components of the each embedding RF-path of the fixture is used for de-embedding purposes. Testing of several phantom-type structures on the chipcarrier level confirms the ability of the considered fixture to give repeatable results for the extracted own MMIC's parameters: mainly for the insertion phase and the gain.
A two-resonator method, based on TE011-mode and TM010-mode resonance cavities with a disk sample ... more A two-resonator method, based on TE011-mode and TM010-mode resonance cavities with a disk sample has been developed for measurement of the longitudinal and transversal dielectric constants and dielectric loss tangent of dielectric substrates (dielectric anisotropy), used in modern electronics. The the- oretical background of the method is presented: the analytical expressions of the dispersion equations for the considered modes in both cavities and expressions of the energy balance for computation of the permittivity and the dielectric loss tangent of the unknown sample in two directions. The sensitivity and the mea- surement errors are discussed. Practical examples are given for illustration of the dielectric anisotropy characterization of modern reinforced substrates with built-in woven glass cloth and filling plastics or powders.
The proposed mission "SofiaUniversitySAT" is focused on development of the "communication functio... more The proposed mission "SofiaUniversitySAT" is focused on development of the "communication function" of small university satellites for support and enhancement of science research and human activities in Antarctica. This function can provide a range of critically important services for Antarctic stations and expeditions, such as: high-speed two-way backhaul data transfer for scientific, safety and other applications using "store-and-forward" technology, offline two-way operational communication services for professional, personal or rescue purposes, continental surface measurements of biological and natural phenomena; weather monitoring and forecasting, etc. Extensive preliminary investigation has been done: selection of suitable frequency bands for university satellites, optimization of on-board planar antenna arrays with adequate gain and directivity, link budget, etc. A concept of time-extended communication sessions between satellite and Antarctic ground station is developed, based on a switchable 5-face on-board antenna panels and steerable ground-station planar antenna panels. Three line-of-sight directions can be switched during a single session in "base" orbit (with trace over the ground station or max ±200 km away): forward, bottom and backward, and two additional lateral directions in two "side" orbits (±1500 km aside the ground station). Link budget in the X band shows that 30-60 Mbps bit rate for 3 min. or ~20 Mbps average bit rate for 9-10 min. in base orbit can be achieved in downlink direction using switchable on-board panels (~10 GB throughput). The proposed communication mode will be designed on a 50-kg small satellite similar to the Russian spacecrafts "Yubileiny-1/2" at a 1500-km altitude near-topolar orbit providing 11 Mbps in the X-band downlink channel during 15-minute long sessions. the need of in-depth exploration of this process. At present, there are virtually no active satellite missions dedicated especially to the needs of Antarctic expeditions mostly because of absence of a single big customer and business niche justifying the cost for development, deployment and operation of a large mainstream satellite system . With recent advancement of small satellite technologies and related subsystems, it becomes possible (according to our investigations) to develop a low-cost, high-performance satellite mission for dealing with the above mentioned communication challenges. This is the goal of our "SofiaUniversitySAT" mission proposal.
An integrated long-term interactive approach is proposed for combining academic science education... more An integrated long-term interactive approach is proposed for combining academic science education with additional methodology for enhancement of personal skills. It aims at making students more efficient both in their studies and further career development. The scope of communication skills includes both teamwork interaction and effective presentation of ideas. Internal motivation covers knowledge and mastery of constructive reasoning and emotional intelligence. Creativity is considered as a life-long progressing mindset and corresponding practical methods are provided. Along these lines, a new format for teaching of modern physics for students of engineering and other fields of science is described. It is based on constant interaction which provides them with an overview of developing trends and their meaning rather than with a system of established facts and their formal mathematical description. Formation of adequate basic concepts of reality in tune with modern fundamental scien...
Outline • Present variants for communications with the Polar Regions -possibilities for voice cal... more Outline • Present variants for communications with the Polar Regions -possibilities for voice calls and data transfer and achievable throughput; • Future projects for non-GEO communication systems; • Idea: Utilization of small university satellites for backhaul communications with the Polar Regions; • Possible frequency bands, antenna systems, extended communication sessions, etc. (connected with the session presentation) • Conclusions
The importance of the dielectric anisotropy of the modern RF substrates is the main focus of the ... more The importance of the dielectric anisotropy of the modern RF substrates is the main focus of the investigations in this chapter. There are two main reasons to want to have information for the actual anisotropy of a given substrate to control the technology (necessary for the manufacturers) and to conduct more realistic simulations of the structures, containing anisotropic materials (necessary for the users). The presented investigations show that the two-resonator method is fully acceptable for determination of the substrate dielectric anisotropy by the help of 3D simulators. The achieved measurement error is less than 3 % for the dielectric constant anisotropy and less than 10 % for the dielectric loss tangent anisotropy in wide frequency range by different pairs of measurement resonators (cylinders, split, coaxial and reentrant cylinders and split-post dielectric resonators) separately for the parallel and for the perpendicular parameters. These parameters can be used in the 3D ...
The paper is dealing with the principles for modeling and simulating by 3D simulators of the well... more The paper is dealing with the principles for modeling and simulating by 3D simulators of the well-known Lüneburg lenses used as communication antenna devices. The models of spherical, semi-spherical and cylindrical multi- layer dielectric lenses are discussed. The results show the effectiveness of the proposed simulation procedures for investigation of the focusing effects and antenna parameters of these large-scale beam-forming devices.
Комуникационна функция на малкия спътник. Комуникационни функции на предния и задния панел – разл... more Комуникационна функция на малкия спътник. Комуникационни функции на предния и задния панел – разлики и приложения Статистически данни за университетските малки спътници и мястото на комуникационните задачи в мисиите досега Нови честотни обхвати, достъпни за малките спътници Енергетичен баланс; ще има ли достатъчно мощност? Възможно ли е предаване не само на статични изображения, но и на телевизионен сигнал по стандарта DVB S2 / DVB T2? Антенна част и функции Удължаване на комуникационната сесия Пример: комуникации с Антарктида Земна станция – функции и реализация Мрежа от университетски земни станции
The necessity for development of the so-called communication function of university small satelli... more The necessity for development of the so-called communication function of university small satellites is considered in this paper. This function can be successfully applied to serve the increasing needs of backhaul and off-line operational communications in the both polar regions. Suitable frequency bands, on-board and ground-station antennas and achievable data throughput are discussed. Communications with the polar regions have been always a big challenge. The up-to-date solutions are more or less limited: the short-wave amateur radio is extremely slow and influenced by weather conditions; the commercial mobile-phone satellite systems are expensive and suitable for voice calls only (data can be sent at unacceptable low bit rate 2.4 kbps); finally, communications through GEO "inclined" satellites (1-1.5 Mbps) (the best solution at the moment) are time and space restricted and unstable (satellites permanently change the position and expensive tracking systems are needed). T...
2011 IEEE EUROCON - International Conference on Computer as a Tool, 2011
An interdisciplinary format of a masters program in microwave communication has been designed and... more An interdisciplinary format of a masters program in microwave communication has been designed and applied as a combination of engineering physics and innovation management training, taking into account latest research on worldwide requirements of business leaders. In addition, students are guided into strategic mentoring relations with academic staff and company managers for development of cutting edge talent.
Слави Баев, Боян Хаджистамов, Пламен Данков.� Лещи на Лунебърг като комуникационни антени Статият... more Слави Баев, Боян Хаджистамов, Пламен Данков.� Лещи на Лунебърг като комуникационни антени Статията се отнася за принципите за моделиране и симулация с ���симулатори на ���симулатори на ��симулатори на �симулатори на симулатори на добре познатите лещи на Люнебърг, използвани като комуникационни антенни устрой� ства. разгледани са модели на сферични, полусферични и цилиндрични многослойни лещи. резутатите показват ефективността на предложената симулационна процедура за изследване на фокусиращия ефект и антенните параметри на тези обемни излъчващи структури.
The measurement of the dielectric constant and loss tangent anisotropy of the planar RF substrate... more The measurement of the dielectric constant and loss tangent anisotropy of the planar RF substrates by the two-resonator method is considered in this paper. The principles of the separate determination of these parameters parallel and perpendicular to the substrate surface is discussed by three pairs of cavity measurement resonators, based on cylinder, reentrant, split cylinder and split post dielectric resonators. Examples of the measured anisotropy of known materials are presented.
The image guide (IG) has been traditionally considered as a perspective for millimeter wavelength... more The image guide (IG) has been traditionally considered as a perspective for millimeter wavelengths. The transition between the standard metal rectangular waveguide (SMRW) and the IG usually exists in every experimental setup involving the IG. Here we have examined experimentally using electric probes the distribution of the electric field components at a double SMRW -IG transition, comprising a dielectric core symmetrically tapered in the H-plane. After that, we have simulated this transition as well as some other transitions using the finite element method (FEM).
The paper considers several spread internal EMC problems, which take place in some microwave pass... more The paper considers several spread internal EMC problems, which take place in some microwave passive nonantenna devices -parasitic radiation, "high-altitude" fields, crosstalk, grounding inefficiency, etc. Near-field scanning combined with electromagnetic simulations have been used for their prediction and detection. Several design rules have been discussed to avoid these problems in the multi-layer antenna arrays up to Ka band.
High-performance measuring multi-port 3-level fixture for active device characterization in the K... more High-performance measuring multi-port 3-level fixture for active device characterization in the Ku-band is described in this paper. It is a low-cost alternative of the expensive microwave "on-wafer" measurements with CPW probes. The method of modeling of the separate components of the each embedding RF-path of the fixture is used for de-embedding purposes. Testing of several phantom-type structures on the chipcarrier level confirms the ability of the considered fixture to give repeatable results for the extracted own MMIC's parameters: mainly for the insertion phase and the gain.
A two-resonator method, based on TE011-mode and TM010-mode resonance cavities with a disk sample ... more A two-resonator method, based on TE011-mode and TM010-mode resonance cavities with a disk sample has been developed for measurement of the longitudinal and transversal dielectric constants and dielectric loss tangent of dielectric substrates (dielectric anisotropy), used in modern electronics. The the- oretical background of the method is presented: the analytical expressions of the dispersion equations for the considered modes in both cavities and expressions of the energy balance for computation of the permittivity and the dielectric loss tangent of the unknown sample in two directions. The sensitivity and the mea- surement errors are discussed. Practical examples are given for illustration of the dielectric anisotropy characterization of modern reinforced substrates with built-in woven glass cloth and filling plastics or powders.
The proposed mission "SofiaUniversitySAT" is focused on development of the "communication functio... more The proposed mission "SofiaUniversitySAT" is focused on development of the "communication function" of small university satellites for support and enhancement of science research and human activities in Antarctica. This function can provide a range of critically important services for Antarctic stations and expeditions, such as: high-speed two-way backhaul data transfer for scientific, safety and other applications using "store-and-forward" technology, offline two-way operational communication services for professional, personal or rescue purposes, continental surface measurements of biological and natural phenomena; weather monitoring and forecasting, etc. Extensive preliminary investigation has been done: selection of suitable frequency bands for university satellites, optimization of on-board planar antenna arrays with adequate gain and directivity, link budget, etc. A concept of time-extended communication sessions between satellite and Antarctic ground station is developed, based on a switchable 5-face on-board antenna panels and steerable ground-station planar antenna panels. Three line-of-sight directions can be switched during a single session in "base" orbit (with trace over the ground station or max ±200 km away): forward, bottom and backward, and two additional lateral directions in two "side" orbits (±1500 km aside the ground station). Link budget in the X band shows that 30-60 Mbps bit rate for 3 min. or ~20 Mbps average bit rate for 9-10 min. in base orbit can be achieved in downlink direction using switchable on-board panels (~10 GB throughput). The proposed communication mode will be designed on a 50-kg small satellite similar to the Russian spacecrafts "Yubileiny-1/2" at a 1500-km altitude near-topolar orbit providing 11 Mbps in the X-band downlink channel during 15-minute long sessions. the need of in-depth exploration of this process. At present, there are virtually no active satellite missions dedicated especially to the needs of Antarctic expeditions mostly because of absence of a single big customer and business niche justifying the cost for development, deployment and operation of a large mainstream satellite system . With recent advancement of small satellite technologies and related subsystems, it becomes possible (according to our investigations) to develop a low-cost, high-performance satellite mission for dealing with the above mentioned communication challenges. This is the goal of our "SofiaUniversitySAT" mission proposal.
An integrated long-term interactive approach is proposed for combining academic science education... more An integrated long-term interactive approach is proposed for combining academic science education with additional methodology for enhancement of personal skills. It aims at making students more efficient both in their studies and further career development. The scope of communication skills includes both teamwork interaction and effective presentation of ideas. Internal motivation covers knowledge and mastery of constructive reasoning and emotional intelligence. Creativity is considered as a life-long progressing mindset and corresponding practical methods are provided. Along these lines, a new format for teaching of modern physics for students of engineering and other fields of science is described. It is based on constant interaction which provides them with an overview of developing trends and their meaning rather than with a system of established facts and their formal mathematical description. Formation of adequate basic concepts of reality in tune with modern fundamental scien...
Outline • Present variants for communications with the Polar Regions -possibilities for voice cal... more Outline • Present variants for communications with the Polar Regions -possibilities for voice calls and data transfer and achievable throughput; • Future projects for non-GEO communication systems; • Idea: Utilization of small university satellites for backhaul communications with the Polar Regions; • Possible frequency bands, antenna systems, extended communication sessions, etc. (connected with the session presentation) • Conclusions
The importance of the dielectric anisotropy of the modern RF substrates is the main focus of the ... more The importance of the dielectric anisotropy of the modern RF substrates is the main focus of the investigations in this chapter. There are two main reasons to want to have information for the actual anisotropy of a given substrate to control the technology (necessary for the manufacturers) and to conduct more realistic simulations of the structures, containing anisotropic materials (necessary for the users). The presented investigations show that the two-resonator method is fully acceptable for determination of the substrate dielectric anisotropy by the help of 3D simulators. The achieved measurement error is less than 3 % for the dielectric constant anisotropy and less than 10 % for the dielectric loss tangent anisotropy in wide frequency range by different pairs of measurement resonators (cylinders, split, coaxial and reentrant cylinders and split-post dielectric resonators) separately for the parallel and for the perpendicular parameters. These parameters can be used in the 3D ...
The paper is dealing with the principles for modeling and simulating by 3D simulators of the well... more The paper is dealing with the principles for modeling and simulating by 3D simulators of the well-known Lüneburg lenses used as communication antenna devices. The models of spherical, semi-spherical and cylindrical multi- layer dielectric lenses are discussed. The results show the effectiveness of the proposed simulation procedures for investigation of the focusing effects and antenna parameters of these large-scale beam-forming devices.
Комуникационна функция на малкия спътник. Комуникационни функции на предния и задния панел – разл... more Комуникационна функция на малкия спътник. Комуникационни функции на предния и задния панел – разлики и приложения Статистически данни за университетските малки спътници и мястото на комуникационните задачи в мисиите досега Нови честотни обхвати, достъпни за малките спътници Енергетичен баланс; ще има ли достатъчно мощност? Възможно ли е предаване не само на статични изображения, но и на телевизионен сигнал по стандарта DVB S2 / DVB T2? Антенна част и функции Удължаване на комуникационната сесия Пример: комуникации с Антарктида Земна станция – функции и реализация Мрежа от университетски земни станции
The necessity for development of the so-called communication function of university small satelli... more The necessity for development of the so-called communication function of university small satellites is considered in this paper. This function can be successfully applied to serve the increasing needs of backhaul and off-line operational communications in the both polar regions. Suitable frequency bands, on-board and ground-station antennas and achievable data throughput are discussed. Communications with the polar regions have been always a big challenge. The up-to-date solutions are more or less limited: the short-wave amateur radio is extremely slow and influenced by weather conditions; the commercial mobile-phone satellite systems are expensive and suitable for voice calls only (data can be sent at unacceptable low bit rate 2.4 kbps); finally, communications through GEO "inclined" satellites (1-1.5 Mbps) (the best solution at the moment) are time and space restricted and unstable (satellites permanently change the position and expensive tracking systems are needed). T...
2011 IEEE EUROCON - International Conference on Computer as a Tool, 2011
An interdisciplinary format of a masters program in microwave communication has been designed and... more An interdisciplinary format of a masters program in microwave communication has been designed and applied as a combination of engineering physics and innovation management training, taking into account latest research on worldwide requirements of business leaders. In addition, students are guided into strategic mentoring relations with academic staff and company managers for development of cutting edge talent.
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