Mutual Coupling

Abstract—In Earth observation programs there is a need of passive low frequency (L-band) measurements to monitor soil moisture and ocean salinity with high spatial resolution 10–20 Km, a radiometric resolution of 1K and a revisit time of 1–3 days [1]. Compared to total power radiometers ...

One of the issues in antenna arrays is the mutual coupling that occurs when two radiating elements are placed together. Mutual coupling can significantly degrade the performance of an antenna array. In this paper, we propose a triangular lattice configuration as a technique to reduce the mutual coupling in patch antenna arrays. A 4-element circular patch array with a triangular lattice is simulated and compared against a 4-element circular patch array with a square lattice in terms of their mutual coupling and radiation pattern. Comparisons are also made with other mutual coupling reduction techniques for closely packed antennas such as ground structure with slits, ground structures with removed substrates and ground structures with metal wall. The triangular lattice concept is then extended to the 9-element circular patch array. The 4-elements circular patch array with the triangular lattice and square lattice operating at 2.6GHz are then fabricated on FR4 printed circuit board.

This paper addresses the issue of “being together,” and more specifically the issue of “being together in time.” We provide with an integrative framework that is inspired by phenomenology, the enactive approach and dynamical systems theories. To do so, we first define embodiment as a living and lived phenomenon that emerges from agent- world coupling. We then show that embodiment is essentially dynamical and therefore we describe experiential, behavioral and brain dynamics. Both lived temporality and the temporality of the living appear to be complex, multiscale phenomena. Next we discuss embodied dynamics in the context of interpersonal interactions, and briefly review the empirical literature on between-persons temporal coordination. Overall, we propose that being together in time emerges from the relational dynamics of embodied interactions and their flexible co-regulation.

Ground station antennas are a part of TTC system, generally, Yagi-Udi antennas and Parabola dish antenna are using in Earth segment to communication with LEO small satellites, this paper uniquely presents the three huge antennas of Beihang University ground station which are communicating with some microsatellites with view window above Beijing, China. The ground station contains two Yagi-Udi antennas for VHF/UHF and an S-band dish antenna for reception of payloads data. For verification feasibility of the antennas, simulations have been accomplished according to the antennas requirements. Eventually, the simulations assisted to recognize the matched commercial ground station antennas based on comparison of the simulations with commercial antennas and the matched ones are chosen for the implementation of Beihang University ground station antennas.

A compact multiple-input-multiple-output (MIMO) antenna with very high isolation is proposed for ultrawideband (UWB) applications. The antenna with a compact size of 30.1 × 20.5 mm 2 (0.31λ 0 × 0.21λ 0) consists of two planar-monopole antenna elements. It is found that isolation of more than 25 dB can be achieved between two parallel monopole antenna elements. For the low-frequency isolation, an efficient technique of bending the feed-line and applying a new protruded ground is introduced. To increase isolation, a design based on suppressing surface wave, near-field, and far-field coupling is applied. The simulation and measurement results of the proposed antenna with the good agreement are presented and show a bandwidth with S 11 ≤ −10 dB, S 12 ≤ −25 dB ranged from 3.1 to 10.6 GHz making the proposed antenna a good candidate for UWB MIMO systems.

Defected ground structures (DGS) have been developed to improve characteristics of many microwave devices. Although the DGS has advantages in the area of the microwave filter design, microstrip antenna design for different applications such as cross polarization reduction and mutual coupling reduction etc., it can also be used for the antenna size reduction. The etching of a defect in the ground plane is a unique technique for the antenna size reduction. The DGS is easy to be an equivalent LC resonator circuit. The value of the inductance and capacitance depends on the area and size of the defect. By varying the various dimensions of the defect, the desired resonance frequency can be achieved. In this paper the effect of dumbbell shaped DGS, to the size reduction of a microstrip patch antenna is investigated. Then a cavity backed structure is used to increase the efficiency of the microstrip patch antenna, in which the electric walls are placed surrounding the patch. The simulation is carried out with IE3D full wave EM simulator.

In this work, the design procedure of a new decoupling network for different antennas is presented for mobile terminals operating in the Sub-1 GHz band (from 0.698 to 0.96 GHz). To evaluate its applicability for different resonant and non-resonant antenna types, two antenna elements have been chosen to be decoupled using the proposed decoupling network: a printed inverted-F antenna and a capacitive coupling element antenna. Simulation and measurement results showed that the decoupling network offer promising improvements in terms of impedance matching, port isolation, envelope correlation coefficient (ECC), and total efficiency. In addition, the antennas are also investigated with the ergodic capacity, multiplexing efficiency, gain, and diversity gain (both calculated using maximal ratio combining technique). Due to the contribution of the decoupling network, the ECC of both types of multiple antennas are less than 0.3, with a 30 % improvement in total efficiency and an inter-element spacing miniaturization of 34 %. INDEX TERMS Decoupling networks, mutual coupling, multi-input multi-output, low frequency, mobile terminal antennas.

Microstrip antenna arrays have found broad applications in recent years and the reduction of mutual coupling is an important criterion in their design. The FDTD method is applied to analyze probe fed patch antennas and the simulated results agree well with the experimental results of R.P. Jedlicka et al. (see IEEE Trans. Antennas Propagat., vol.29, p.147-9, 1981). The mutual coupling of patch antennas on a high dielectric constant substrate, which is of growing interest due to its compact size and conformability with MMIC, is characterized in detail. Such antennas have larger mutual coupling than antennas on a low permittivity substrate because of the pronounced surface waves. The electromagnetic band-gap structure introduced by D. Sievenpiper et al. (see IEEE Trans. MTT, vol.47, p.2059-74, 1999) is then employed to inhibit the surface waves so that the mutual coupling is greatly reduced.

The CO 2 geological storage in Ordos Basin and coal mining activities occurring simultaneously at the same location is a highly challenging coupled thermo-hydro-mechano-chemical (THMC) problem. To address this problem, an in-house program named " AEEA Coupler " was developed by linking two commercial software packages , Simulia ABAQUS and Schlumberger ECLIPSE, both of which are widely used and highly recognized in their respective fields. The applicability and accuracy of the developed coupler were tested by benchmark studies. A coupled multi-physics analysis was conducted based on real formation data of the Ordos and Shenhua CCS Demonstration Project with an injection rate of 0.1 Mtpa (Million tonnes per annum). A larger injection rate of 1.0 Mtpa was also investigated to explore the potential for the commercialization of large-scale CCS projects in the area. The primary conclusions that were obtained from the numerical simulations are as follows: (a) The pore pressure and displacement at the top of the reservoir increase with CO 2 injection, and the displacement continues to increase even after the termination of the CO 2 injection due to the coal mining activity. (b) The displacement of the wellbore peaks at the coal seam floor where the axial strain of the well soars abruptly. Our work suggests that the distance between coal pillars should be at least 90 m to ensure that the Mises stress of the casing is below the designed safe value. (c) The tensile stress and shearing stress increase significantly in the caprock as a result of the coupling of the two engineering activities; therefore, damages in the caprock occur more easily. (d) After CO 2 injection, only the strata with a depth of less than 769 m are affected by the coal mining activity. (e) The combined activities achieve a surface subsidence reduction comparable to that of only coal mining. Finally, several recommendations are given regarding the actual engineering implementation of the combined activities.

De Tao die kan worden uitgesproken, is niet de eeuwige Tao."
Lao Tze (China ca 4000 jaar geleden)

Een vreemd pad om bij spirituele commons uit te komen

Van Morrison sang in1968 …I ain't nothing but a stranger in this world…could you find me? would you kiss my eyes? and lay me down …in silence easy…to be born again…in another time…in another place…. on: Astral Weeks

Worstelend met deze tekst realiseerde ik me - terugkijkend als een grootvader op 74-jarige leeftijd - dat het een vreemde zoektocht is geweest om in spirituele commons te eindigen. Ik voelde mij altijd, zelfs als kind in mijn eigen families van oorsprong, 'niet op mijn plaats' en maakte er een levenslange zoektocht van om 'op mijn plaats' te komen.

In this paper three types of Electromagnetic Band
Gap (EBG) structure is presented. This paper  analyze the
parametric performance  of different factors that influence band
gap properties of EBG structures. Planer Electromagnetic Band
Gap (EBG) structures are considered very promising in
microwave engineering. It is found that EBG structures used to
reduce interference, surface wave and mutual coupling. This
paper includes three designs of EBG structures including Fractal
shaped, Fork shaped and Spiral shaped. The array of theses EBG
structures has been also  analyzed to investigate the Band Gap
Properties of these structures. Finally the comparison of band gap
properties of all three EBG structures has been compared,
discussed and concluded

A comparative analysis is undertaken to study the effect of directivity in direction-of-arrival (DOA) estimation. Two different kinds of antenna arrays, viz. isotropic and directional are used to estimate predetermined angle-of-arrival (AOA) correctly using MUSIC (Multiple Signal Classification) super-resolution algorithm. Simulation results show that the performance of DOA depends entirely on the algorithm for isotropic antenna arrays, whereas directional antenna array requires both the algorithm efficiency and appropriate position of the main beam at any time instant to estimate DOA accurately. This study concludes that, in practical applications, both DOA algorithm and the beam pattern play crucial roles in ensuring the correct DOA estimation. The effect of array mutual coupling on direction finding is also studied using rigorous electromagnetic computation and the MUSIC algorithm. The various scenarios studied include inter-element spacing and noise level. Simulation results quantitatively show the effect of mutual coupling on DOA estimation that, in turn, reinforces the necessity of accounting and compensating for mutual coupling effect in DOA estimation process.

A simple technique to reduce the mutual coupling between patch antenna arrays is proposed. Mutual coupling phenomena in patch antenna array are investigated and according to the coupling characteristics, a simple rectangular slot(s) placed in between the patch elements is proposed. An equivalent circuit of the proposed structure is obtained through the reciprocity method. In the proposed technique, the series equivalent circuit of the slot is used to reduce the mutual coupling level without changes to the back lobe as well as cross-polarisation levels compared to conventional arrays. The mutual coupling reduction is >20 dB when compared with the conventional array. Applied to a phased array antenna, the reduction in the mutual coupling results in a wider scan range, up to 75°. A parametric study is carried out for different parameters of the slot that affect the mutual coupling and the scan range. A prototype of the antenna array is fabricated and the measured results are compared to the simulation.

A comprehensive study of the mutual coupling between two rectangular microstrip patch antennas is presented. Using the cavity model, numerical results for both mutual impedance and mutual coupling parameter are given for the E-plane, H-plane, diagonal, and perpendicular orientations. The effects of substrate thickness, substrate permittivity, and feed positions are discussed. © 1992 John Wiley & Sons, Inc.

The paper summarizes a new modeling procedure for 3D virtual design of EMI filter circuits. The proposed method, based on the coupling of the Partial Element Equivalent Circuit (PEEC) and Boundary Integral Method (BIM) methods, extends the standard PEEC approach for modeling in the presence of magnetic materials, hence allowing the PEEC-based modeling of toroidal EMI filter inductors. The PEEC-BIM

This paper presents a summary of research work on the modelling and development of power factor improvement techniques for switched reluctance motor (SRM) drives. Four models of SRM are presented, which include an interpolation model using two-dimensional (2-D) bicubic spline, an analytical model based on 2-D least squares technique, a hybrid model based on 2-D bicubic and 2-D bilinear splines,

Antenna mutual coupling occurs naturally through the electromagnetic field.  It is sometimes neglected in design with serious  consequences. Mutual coupling has also been used to improve the performance of arrays by placing the elements closer together or with nearby parasitics. Whilst detailed design is possible through the several accurate computer packages that are available, greater understanding of what is possible by direct connection with the physics through analysis that often creates simple models. The intention of this book is to cover the main techniques that depend clearly on an understanding through Maxwell’s equations. It covers the subject of mutual coupling comprehensibly through topics written by experts in the area. These topics include coupling in wire antennas, waveguides and horns, co-sited antennas, MIMO antenna, large arrays, and measurement techniques.

Table of Contents
Chapter 1  Introduction (Trevor S. Bird)
Chapter 2  Basics of Antenna Mutual Coupling (Trevor S. Bird)
Chapter 3  Methods in the Analysis of Mutual Coupling in Antennas (Trevor S. Bird)
Chapter 4  Mutual Coupling in Arrays of Wire Antennas (Trevor S. Bird)
Chapter 5  Arrays of Planar Aperture Antennas (Trevor S. Bird)
Chapter 6  Arrays of Microstrip Patch Antennas (Trevor S. Bird)
Chapter 7  Mutual Coupling Between Antennas on Conformal Surfaces (Trevor S. Bird)
Chapter 8  Mutual Coupling Between Co-sited Antennas and Antennas on Large Structures (Derek McNamara and Eqab Almajali)
Chapter 9 Mutual Coupling and Multiple Input Multiple Output (MIMO) Communications (Karl F. Warnick)
Chapter 10  Mutual Coupling in Beamforming and Interferometric Antennas (Hoi Shun Antony Lui and Trevor S. Bird)
Chapter 11 Techniques for Minimizing Mutual Coupling Effects in Arrays (Hoi Shun Antony Lui and Trevor S. Bird)
Chapter 12  Noise Performance in the Presence of Mutual Coupling (Christophe Craeye, Jean Cavillot, and Eloy de Lera Acedo)
Chapter 13  Methods for Analyzing Mutual Coupling in Large Arrays
(Christophe Craeye and Ha Bui Van)
Chapter 14  Measurement of Mutual Coupling Effects (Alpha O. Bah and Trevor S. Bird)
APPENDIX A: Useful Identities (Trevor S. Bird)
APPENDIX B: Bessel and Hankel Functions (Trevor S. Bird)
APPENDIX C: Properties of Hankel Transform Functions (Trevor S. Bird)
APPENDIX D: Properties of Surface Fock Functions (Trevor S. Bird)
APPENDIX E: Four Parameter Noise Representation of an Amplifier (Christophe Craeye, Jean Cavillot, and Eloy de Lera Acedo)
APPENDIX F: Equivalent Noise Currents (Christophe Craeye, Jean Cavillot, and Eloy de Lera Acedo)
APPENDIX G: Basic Reciprocity Result (Christophe Craeye, Jean Cavillot, and Eloy de Lera Acedo)
APPENDIX H: On the Extended Admittance Matrix (Christophe Craeye and Ha Bui Van)
(Index