Design and Performance Analysis of a Compact Quad-Element UWB MIMO Antenna for Automotive Communications

This paper presents the design and analysis of a planar ultra-wideband (UWB) multiple-input-multiple-output (MIMO) antenna for modern vehicular communication systems. The proposed unit cell antenna structure was designed using modified elliptical radiators on a Rogers RO3003 substrate, has a size of 22 × 22 × 0.76 mm3, and covers an impedance bandwidth (S11 ≤ −10 dB) of 3.14 GHz to 12.24 GHz. The peak gain and efficiency of the unit cell prototype are 5.1 dBi and 81%, respectively. The unit cell was further developed into a MIMO antenna configuration with four elements placed orthogonal to each other in a single plane measuring 50 × 50 × 0.76 mm3. The measured isolation between the antenna elements was greater than 20 dB. The measured envelope correlation coefficient (ECC) of the MIMO antenna was less than 0.004, the diversity gain (DG) was greater than 9.67 dB, the total active reflection coefficient (TARC) was <−10 dB, and the mean effective gain (MEG) ratio was > 0.99. The characteristics of the proposed unit cell and the MIMO antenna were investigated for housing effects in order to validate the consistent performance of the antenna in the presence of conducting bodies. In addition, the radiation characteristics of the antenna when mounted on a vehicle were analyzed using a virtual model of the car. The results show that the proposed quad-element UWB MIMO array is compact, has good performance, and is well-suited for automotive applications.

Evolution of Sliding Contact Wear Between Deformable Conducting Bodies via a Multiphysics Framework

A multiphysics computational framework is introduced and exercised to predict the wear behavior of two deformable, heat-conducting bodies under conditions of sliding contact. This framework enables the solution of a coupled system of partial differential equations (PDEs) expressing the conservation of energy and momentum along with two ordinary differential equations (ODEs) expressing mass conservation. This system is intended to capture wear evolution for each of the bodies forming a wear pair, in a self-consistent manner. Furthermore, an arbitrary-Lagrangian-Eulerian approach has been integrated to enable tracking the evolution of the wear fronts on both elements of the sliding contact pair through physics-informed mesh deformation. A theorem and a corollary are proved to indicate that most existing models describing wear that are expressed in the form of an ODE are actually manifestations of the law of conservation of mass. The framework is applied for two distinct slider-base pairs. The first involves an aluminum alloy slider and a copper alloy base. The second pair is identical to the first except it contains a thin strip of soda-lime glass embedded in the surface of the base. The effects of this glass layer on the wear of all participating bodies in comparison to the pair that does not contain this layer are presented. They indicate that while the glass layer has a wear mitigation effect for the stationary base it slightly increases the wear of the slider when compared with the respective bodies when the glass is not present.

О силе электростатического взаимодействия между двумя проводящими сфероидами

Application of finite element method for calculation of electrostatic interaction force of two conducting bodies of spheroidal shape with preset charges on their surfaces in zero external field is considered.

On the Effect of Glassy Coatings on the Wear of a Sliding Contact via Multiphysics Modeling

A recently developed multiphysics computational framework is exercised to predict the wear behavior of two deformable and heat conducting bodies under conditions of sliding contact. This framework enables the solution of a high dimensional thermo-mechanical problem simultaneously and tightly coupled with the associated wear evolution models for each of the wear pair bodies, thus enabling predictions of wear for both of them. Two distinct slider-base pairs are modeled. The first involves an aluminum alloy slider and a copper alloy base. The second is a pair identical to the first except it contains a thin strip of soda lime glass embedded in the surface of the base. The objective of this effort is to establish the effects of this glass layer on the wear of all participating bodies in comparison to the pair that does not contain this layer. The results indicate that while the glass layer has a wear mitigation effect for the stationary base it slightly increases the wear of the slider when compared with the respective bodies when the glass is not present.

Approximation of Current on a Thin Tubular Vibration Antenna Using the Eigenfunction Method

The article considers the method of eigenfunctions for getting the approximated current solution to the internal problem of electrodynamics. The paper considers a polynomial frequency dependence approximation of the eigenvalues and eigenfunctions of the operator for conducting bodies. The current solutions obtained by the straightforward method and with the help of method using the comparison of two approximation types.