Consideration Of Mutual Coupling Research Articles

Development of an analytical method for pattern synthesizing of linear and planar arrays with optimal parameters

Typically, in the synthesis problem of an equally-spaced array, the number of array elements and the element spacing should be specified before. In this paper, based-on the Nyquist–Shannon sampling theorem, a new procedure is introduced, which is used in choosing the optimal value of the number of array elements and the element distance. After specifying the number of array elements and the element spacing, an analytical method based-on the integral transform with the Gegenbauer kernel is used for the calculation of the excitation weights of the array. Also, directivity, amplitude dynamic range and mutual coupling considerations are regarded in the introduced procedure. Additionally, it is shown that the proposed method can be developed for planar and ring arrays. Several test cases with special features are examined to verify the performance of the presented method.

Development of an allocation method to synthesis of unequally spaced arrays with minimum number of elements and mutual coupling considerations

A method is proposed to synthesize unequally spaced arrays so that it has minimum number of elements. Also, it is shown that the proposed method can reduce the total number of elements of equally spaced arrays. The advantage of the proposed method is that it is very fast and straightforward. In this method, the locations of array elements are calculated by considering the mutual coupling between two adjacent array elements, first. After determining the elements locations, two scenarios may be existed. In the first scenario, conventional least square method is proposed. In the second scenario and to increase the accuracy of the final design, recursive least square estimation algorithm is suggested. Mean square error between the desired and synthesized pattern is considered to measure the performance of the method. Several arrays are examined to check the performance of the proposed method. Since, the matrix pencil method (MPM) method has been widely used in the design of nonuniformly spaced arrays, in all examples, the results of MPM technique are considered in comparison process. The obtained results show that the proposed method has a good performance both in reducing the number of array elements and in the accuracy of the synthesized pattern, especially for arrays with beam-shaped pattern such as flat-top and cosecant radiation patterns.

100 GHz Silicon‐based micro‐machined patch antenna and arrays

This study designs a micro-machined BCB-cavity patch antenna and two types of four-element micro-machined antenna arrays at 100 GHz. The patches are fabricated on Benzocyclobutene (BCB) polymer material. The silicon substrate is selective lateral etched under the patch antenna to fabricate a cavity surrounded by metal and filled with BCB material. The BCB-cavity under patches can reduce the excitation of surface waves and enhance the radiation on performance. A single large BCB-cavity is designed to implement the four-element antenna arrays under the consideration of mutual coupling. The proposed single antenna has a 2.8 GHz impedance bandwidth. At 100 GHz, the simulated maximum gain is 6.7 dBi for the single antenna and 13 dBi for the four-element antenna arrays.

A Low Cross-Polarization Slotted Ridged SIW Array Antenna Design With Mutual Coupling Considerations

A novel shunt longitudinal slot planar array antenna based on a ridged substrate integrated waveguide (RSIW) with a good cross polarization and isolation is designed and fabricated. The slots in the proposed structure are placed on the centerline of the broad wall of the substrate integrated waveguide (SIW), in order to reduce cross polarization. Also, the asymmetric field distributions on both sides of each slot, which are required for making radiation possible, are realized through using ridges close to the narrow walls of the SIW. The admittance of a single slot in the proposed structure is obtained regarding the different values of the main parameters of the structure. An eight-element longitudinal slot array antenna on the broad wall of the RSIW is designed based on Elliots design procedure. In this design, internal and external mutual coupling effects are taken into account through calculating the active admittance for each slot of the array. A 2D graph is presented which contains the real and imaginary parts of the equivalent admittance of a slot based on the changes in the widths of the ridges and length of the slot. Using this graph, the widths of the ridges and length of the slot can be revised in a way that the mutual coupling effect is taken into account. Since the array antenna is composed of collinear elements, it demonstrates a better cross polarization and isolation in comparison with conventional slot array antennas. Simulation results show good agreement with measurement results of the fabricated proposed antenna.

On the MIMO channel capacity saturation for spatially constrained receive region

In MIMO wireless communication systems, when more and more antennas are packed into spatially-limited receive region, the antenna saturation phenomenon will appear. Moreover, the electromagnetic interactions among antennas will also become stronger and stronger and affect the antenna saturation effect considerably. Despite this, few studies consider these two effects jointly. The effects of antenna saturation are investigated under the consideration of mutual coupling, thus a more practical and physically meaningful result can be obtained.

Mutual Coupling Between Box-Horn Elements of a Phased Array Terminated in Three-layered Bio-Media

The ldquoplane wave spectral techniquerdquo is used to investigate theoretically the extent of mutual coupling between two box-horn elements of a phased array terminated in three-layered bio-media (skin, fat, and muscle layers). The results obtained have been validated against published results in the literature. Each box-horn of the array is assumed to be filled with water to provide good impedance match to the bio-media. Also, it reduces the dimensions of each box-horn which makes it suitable for array configuration. The effects of relative position of elements, spacing between elements, frequency, aperture size of each element, relative phase and amplitude of excitation of the elements on mutual coupling coefficients are numerically investigated and presented for an array of two box-horns terminated in bio-media. The specific absorption rate (SAR) distributions along the direction of the array axis in muscle layer of the bio-media in direct contact with a collinear array of two box-horns both with and without mutual coupling considerations are also computed and presented. The results of the present research work can provide useful design guidelines for the development of prototypes of box-horn array for hyperthermia treatment of tumors. Bio-media, box-horn, hyperthermia, mutual coupling, phased array, plane wave spectra.

Array pattern synthesis using neural networks with mutual coupling effect

In the paper a neural network algorithm is presented for the synthesis of array patterns in the presence of mutual coupling. The algorithm is based on wavelet activation functions and is tested on a linear dipole array with a shaped pattern. The excitations and the lengths of the dipoles in the array are determined. The architecture of the neural network is discussed and simulation results are presented. The proposed algorithm makes the synthesis procedure more practical and accurate compared to the synthesis technique without mutual coupling considerations.

Surge Characteristics of Propulsion Coils Including Mutual Coupling for Maglev

A superconducting magnetic levitation system (Maglev) employs a linear synchronous motor (LSM) with primary side on ground. In the system, a combined levitation and guidance system arranging propulsion coils on the surface of the sidewall is used. Also, propulsion coils are electro-magnetically coupled to each other because they are attached in double layers. Therefore, propulsion coils on the both sidewalls are electro-magnetically coupled with the combined levitation and guidance system. This means that the surge characteristics of the system will be very complicated.As one of the analysis of the electric surge of such an electro-magnetically complicated system of Maglev, we measured the surge between propulsion coils and simulated it using EMTP (Electro-Magnetic Transients Program) in consideration of mutual coupling between coils. After confirming the agreement of the simulated results and the experimental results, characteristics for the practical large system such as Yamanashi Test Line are discussed.

Real-time frequency and 2-D angle estimation with sub-Nyquist spatio-temporal sampling

An algorithm is presented for real-time estimation of the frequency and azimuth and elevation angles of each signal incident on an airborne antenna array system over a very wide frequency band (2-18 GHz) commensurate with electronic signal warfare. The algorithm provides unambiguous frequency estimation despite severe temporal undersampling necessitated by cost/complexity of hardware considerations. The 2-18 GHz spectrum is decomposed into 1-GHz bands. The baseband output of each antenna is sent through two 250-MHz sampled channels where one is delayed relative to the other (prior to sampling) by 0.5 ns, which is the Nyquist interval for a 1-GHz bandwidth. Due to the high variance of the Direct ESPRIT frequency estimator, aliased frequencies are estimated via a simple formula and translated to the proper aliasing zone, utilizing eigenvector information generated by PRO-ESPRIT. The algorithm also provides unambigous 2-D angle estimate over the entire 2-18 GHz bandwidth, despite severe spatial undersampling at the higher end of this band necessitated by mutual coupling considerations and resolving power requirements at the lower end of the band. Eigenvector information generated by PRO-ESPRTT is used to facilitate computationally simple estimation of azimuth and elevation angles that are automatically paired with corresponding frequency estimates despite aliasing. Simulations are presented demonstrating the capabilities of the algorithm. >

Mutual Coupling Considerations in Linear-Slot Array Design

A study was made of the mutual coupling between two resonant waveguide fed slots on a finite ground plane. The size of the ground plane and the relative spacing of the slots were such that the geometry corresponded to that of a pair of adjacent longitudinal shunt slots on the broad face of a rectangular waveguide. A null bridge method of measurement was used to determine accurately the relative field strength excited in the second waveguide by mutual coupling between the slots when the generator was applied to the first waveguide. The change in input slot admittance of the driven slot arising from the presence of the parasitic slot was also measured for matched terminations of the ends of the parasitic slot waveguide. The changes in slot input admittance and excitation arising from mutual coupling were determined. It is shown that the changes may be neglected in the design of the great majority of linear-slot arrays.