Power Transfer Efficiency Analyzed using Characteristic Mode Coupling Between Two Parallel Loops

[EN] Independently of any electrical contact, running electronic devices such as smartphones, smart watches, RFID tags etc., is now attainable over small and large distances through Wireless Power Transfer technology. Although, designing systems maintaining appreciable power transfer efficiency still not always achievable. Using two parallel loops, the Theory of Characteristic Modes provides physical insight into the power transfer efficiency. Furthermore, to reach straightforward maximization of the modal power transfer efficiency, the focus of this paper is analyzing the impact of the separation distance and the overlapping between the two antennas on the characteristic modes and their contribution in the total efficiency of the power. The study considers different positions and frequencies of the two parallel antennas.This work has been supported by the Spanish Ministry of Science, Innovation and Universities (Ministerio Ciencia, Innovación y Universidades) under the project TEC2016- 78028-C3-3-P.Abderrazak, F.; Antonino Daviu, E.; Ferrando Bataller, M. (2020). Power Transfer Efficiency Analyzed using Characteristic Mode Coupling Between Two Parallel Loops. IEEE. 1-5. https://doi.org/10.23919/EuCAP48036.2020.9135229S1

Metamaterial based design of compact UWB/MIMO monopoles antenna with characteristic mode analysis

In this article, a novel metamaterial inspired UWB/multiple-input-multiple-output (MIMO) antenna is presented. The proposed antenna consists of a circular metallic part which formed the patch and a partial ground plane. Metamaterial structure is loaded at the top side of the patches for bandwidth improvement and mutual coupling reduction. The proposed antenna provides UWB mode of operation from 2.6-12 GHz. The characteristic mode theory is applied to examine each physical mode of the antenna aperture and access its many physical parameters without exciting the antenna. Mode 2 was the dominant mode among the three modes used. Considering the almost inevitable presence of mutual coupling effects within compact multiport antennas, we developed an additional decoupling technique in the form of perturbed stubs, which leads to a mutual coupling reduction of less than 20 dB. Finally, different performance parameters of the system, such as envelope correlation coefficient (ECC), channel capacity loss (CCL), diversity gain, total active reflection coefficient (TARC), mean effective gain (MEG), surface current, and radiation pattern, are presented. A prototype antenna is fabricated and measured for validation

High Performance Antenna System in MIMO Configuration for 5G Wireless Communications Over Sub-6 GHz Spectrum

This paper presents a high-performance multiple input and multiple output (MIMO) antenna comprising 2 x 2 configuration of radiating elements that is designed for sub-6 GHz applications. The proposed MIMO antenna employs four identical radiating elements. High isolation between the radiating elements and therefore reduced mutual coupling is achieved by spatially arranging the radiating elements in an orthogonal configuration. Also, a novel frequency selective surface (FSS) was employed to increase the gain of the MIMO antenna over a wide bandwidth from 3 to 6 GHz. This was achieved by locating the FSS above the antenna at a certain height. The FSS essentially enhanced the antenna's directivity, reduced back lobe radiation and mutual coupling. The antenna was fabricated on a standard Rogers RT Duroid 5880 dielectric substrate with a 0.8 mm thickness. The overall dimension of the MIMO antenna is 50 x 50 x 12.5 mm(3) and it operates from 3.8 to 6 GHz, which corresponds to a fractional bandwidth of 41%. The proposed MIMO antenna has a measured peak gain of 4.8 dBi and inter radiation element isolation >20 dB. Its envelope correlation coefficient is <0.1 and diversity gain >9.9 (dB). These characteristics make the proposed MIMO antenna system suitable for 5G communication systems

High Performance Antenna System in MIMO Configuration for 5G Wireless Communications Over Sub-6 GHz Spectrum

This paper presents a high-performance multiple input and multiple output (MIMO) antenna comprising 2 × 2 configuration of radiating elements that is designed for sub-6 GHz applications. The proposed MIMO antenna employs four identical radiating elements. High isolation between the radiating elements and therefore reduced mutual coupling is achieved by spatially arranging the radiating elements in an orthogonal configuration. Also, a novel frequency selective surface (FSS) was employed to increase the gain of the MIMO antenna over a wide bandwidth from 3 to 6 GHz. This was achieved by locating the FSS above the antenna at a certain height. The FSS essentially enhanced the antenna's directivity, reduced back lobe radiation and mutual coupling. The antenna was fabricated on a standard Rogers RT Duroid 5880 dielectric substrate with a 0.8 mm thickness. The overall dimension of the MIMO antenna is 50 × 50 × 12.5 mm3 and it operates from 3.8 to 6 GHz, which corresponds to a fractional bandwidth of 41%. The proposed MIMO antenna has a measured peak gain of 4.8 dBi and inter radiation element isolation >20 dB. Its envelope correlation coefficient is <0.1 and diversity gain >9.9 (dB). These characteristics make the proposed MIMO antenna system suitable for 5G communication systems

Multi-Band Small Antennas for Mobile Terminals

The thesis presents several novel ideas of designing electrically small antennas for mobile terminals such as mobile phones. As the fifth generation wireless systems (5G) is coming soon, radio signals at sub 6 GHz and millimetre-wave (mmWave) frequencies will be employed in mobile communication. In this thesis, the author concentrates on the antennas at sub 6 GHz, because the signals at sub 6 GHz will still play an important role in 5G mobile communication due to the advantage of signal penetration through buildings. The research areas consist of main antenna and multi-input multi-output (MIMO) antenna technology including decoupling techniques and MIMO antenna unit. First, a novel six-mode loop antenna as a main antenna is proposed for mobile phones. Loop antennas offer better user experience than monopole antennas, inverted-F antennas (IFA), and planar inverted-F antennas (PIFA) because of the unique balanced modes (1?, 2?, ...). However, the balanced modes also cause narrower bandwidth of loop antennas. In order to overcome the bandwidth problem, how to reach the upper limit of the existing operating modes and how to create more modes are explored. A novel monopole/dipole parasitic element, which operates at an unbalanced monopole-like 0.25? mode and a balanced dipole-like 0.5? mode, is firstly proposed. In order to validate the concept, one prototype with the dimension of 75×10×5 mm3 is designed, fabricated, and measured. The antenna is able to cover 660-1100 MHz, 1710-3020 MHz, 3370-3900 MHz, and 5150-5850 MHz, which is wide enough for almost all the service of mobile telecommunication systems. Then, a multimode decoupling technique is proposed for wideband/multiband isolation enhancement in compact volume. Although decoupling techniques have been researched for many years, multimode decoupling technique remains a great challenge for mobile terminals. One difficulty in achieving multi decoupling modes is that the operating modes of closely-packed decoupling elements have very strong mutual effect, which makes the tuning complicated and even unfeasible. Thus, in physical principle, a novel idea of achieving the stability of the boundary conditions of decoupling elements is proposed to solve the mutual effect problem; in physical structure, a metal boundary is adopted to realize the stability. One distinguished feature of the proposed technique is that the independent tuning characteristic can be maintained even if the number of decoupling elements increases. Therefore, wideband/multiband high isolation can be achieved by isolating multi decoupling elements. To validate the concept, two case studies are given. In a quad-mode decoupling design, the isolation is enhanced from 12.7 dB to > 21 dB within 22.0% bandwidth by using a 0.295?0×0.059?0×0.007?0 decoupling structure. Finally, a novel principle, namely differential/common mode (DM/CM) design, is proposed to achieve highly integrated MIMO antenna unit in mobile terminals. The inspiration comes from a dipole fed by a differential line which can be considered as differential mode (DM) feed. What will happen if the DM feed is transformed into a common mode (CM) feed? Some interesting features are found in the research. By symmetrically placing one DM antenna and one CM antenna together, a DM/CM antenna can be achieved. Benefitting from the coupling cancellation of anti-phase currents and the different distributions of the radiation currents, a DM/CM antenna can obtain high isolation and complementary patterns, even if the radiators of the DM and CM antennas are overlapped. Therefore, good MIMO performance can be realized in a very compact volume. To validate the concept, a miniaturized DM/CM antenna unit is designed for mobile phones. 24.2 dB isolation and complementary patterns are achieved in the dimension of 0.330?0×0.058?0×0.019?0. One 8×8 MIMO antenna array is constructed by using four DM/CM antenna units and shows good overall performance. The proposed idea of DM/CM design may be promising for other applications that need high isolation and wide-angle pattern coverage

The Development of Novel Interconnection Technologies for 3D Packaging of Wire Bondless Silicon Carbide Power Modules

This dissertation advances the cause for the 3D packaging and integration of silicon carbide power modules. 3D wire bondless approaches adopted for enhancing the performance of silicon power modules were surveyed, and their merits were assessed to serve as a vision for the future of SiC power packaging. Current efforts pursuing 3D wire bondless SiC power modules were investigated, and the concept for a novel SiC power module was discussed. This highly-integrated SiC power module was assessed for feasibility, with a focus on achieving ultralow parasitic inductances in the critical switching loops. This will enable higher switching frequencies, leading to a reduction in the size of the passive devices in the system and resulting in systems with lower weight and volume. The proposed concept yielded an order-of-magnitude reduction in system parasitics, alongside the possibility of a compact system integration. The technological barriers to realizing these concepts were identified, and solutions for novel interconnection schemes were proposed and evaluated. A novel sintered silver preform was developed to facilitate flip-chip interconnections for a bare-die power device while operating in a high ambient temperature. The preform was demonstrated to have 3.75× more bonding strength than a conventional sintered silver bond and passed rigorous thermal shock tests. A chip-scale and flip-chip capable power device was also developed. The novel package combined the ease of assembly of a discrete device with a performance exceeding a wire bonded module. It occupied a 14× smaller footprint than a discrete device, and offered power loop inductances which were less than a third of a conventional wire bonded module. A detailed manufacturing process flow and qualification is included in this dissertation. These novel devices were implemented in various electrical systems—a discrete Schottky barrier diode package, a half-bridge module with external gate drive, and finally a half-bridge with integrated gate driver in-module. The results of these investigations have been reported and their benefits assessed. The wire bondless modules showed \u3c 5% overshoot under all test conditions. No observable detrimental effects due to dv/dt were observed for any of the modules even under aggressive voltage slew rates of 20-25 V/ns

High performance antenna system in MIMO configuration for 5G wireless communications over sub-6 GHz spectrum

This paper presents a high-performance multiple input and multiple output (MIMO) antenna comprising 2 × 2 configuration of radiating elements that is designed for sub-6 GHz applications. The proposed MIMO antenna employs four identical radiating elements. High isolation between the radiating elements and therefore reduced mutual coupling is achieved by spatially arranging the radiating elements in an orthogonal configuration. Also, a novel frequency selective surface (FSS) was employed to increase the gain of the MIMO antenna over a wide bandwidth from 3 to 6 GHz. This was achieved by locating the FSS above the antenna at a certain height. The FSS essentially enhanced the antenna's directivity, reduced back lobe radiation and mutual coupling. The antenna was fabricated on a standard Rogers RT/Duroid 5880 dielectric substrate with a 0.8 mm thickness. The overall dimension of the MIMO antenna is 50 × 50 × 12.5 mm3 and it operates from 3.8 to 6 GHz, which corresponds to a fractional bandwidth of 41%. The proposed MIMO antenna has a measured peak gain of 4.8 dBi and inter radiation element isolation >20 dB. Its envelope correlation coefficient is 9.9 (dB). These characteristics make the proposed MIMO antenna system suitable for 5G communication systems

Compact antenna arrays in mobile communications: A quantitative analysis of radiator coupling

To meet the ongoing demand for higher data rates and greater user mobility, modern mobile communications systems increasingly employ adaptive antenna arrays. By moving antenna elements closer together, to fit them inside a cellular phone for instance, mutual coupling effects impair their radiation capabilities. To describe these impairments more descriptively in contrast to current approaches, the present thesis extends the familiar notion of radiation efficiency from a single radiator to arbitrary antenna arrays by introducing an orthogonal set of radiating degrees of freedom. Detailed examples illustrate the effects of mutual coupling. Decoupling and matching networks are introduced to counteract mutual coupling. Thus, a design method applicable to a broad class of antenna arrays is described and verified by numerous examples, thereby ohmic losses and narrow bandwidths are identified as major weaknesses of decoupling and matching networks in general. For an investigation of the influence of mutual coupling on a mobile diversity receiver system, closed-form expressions for its diversity gain are derived and discussed. The analysis is complemented by a comprehensive receiver noise model. Practical diversity and noise measurements confirm the validity of the theoretical concepts developed. The present work aims to convey a more descriptive understanding of radiator coupling and to raise awareness of the fact that aspects of the entire system must be accounted for for an objective assessment of the potentials of mutually coupled antenna arrays