In this paper, a vehicular antenna design scheme that considers vehicular body effects is proposed. A wire antenna for the global positioning system (GPS) and long-term evolution (LTE) systems is implemented on a plastic plate and then mounted on a windshield of the vehicle. Common outputs are used to allow feed sharing. It is necessary to increase the GPS right-hand circularly polarization (RHCP) gain near the zenith and to reduce the axis ratio (AR). For LTE, we need to increase the horizontal polarization (HP) gain. In addition, for LTE, multiband characteristics are required. In order to achieve the specified performance, the antenna shape is optimized via a Pareto genetic algorithm (PGA). When an antenna is mounted on the body, antenna performance changes significantly. To evaluate the performance of an antenna with complex shape mounted on a windshield, a commercial electromagnetic simulator (Ansoft HFSS) is used. To apply electromagnetic results output by HFSS to the PGA algorithm operating in the MATLAB environment, a MATLAB-to-HFSS linking program via Visual BASIC (VB) script was used. It is difficult to carry out the electromagnetic analysis on the entire body because of the limitations of the calculating load and memory size. To overcome these limitations, we consider only that part of the vehicle's body that influences antenna performance. We show that a series of optimization steps can minimize the degradation caused by the vehicle`s body. The simulation results clearly show that it is well optimized at 1.575GHz for GPS, and 0.74 ∼ 0.79GHz and 2.11 ∼ 2.16GHz for LTE, respectively.

Comparison of the electromagnetic characteristics of a monopole-type wire antenna (MTWA) and an inverted-F wire antenna (IFWA) is performed based on numerical and experimental results. Radiation characteristics, when the handset model is located in the vicinity of a head phantom or in free space, are also investigated. The gain of 8.27 dBi is achieved at 3.4 GHz for the MTWA with the head phantom.

A new approach for solution of the Tensor-Volume Integral Equation (TVIE) using Galerkin-based moment method (MoM) for three-dimensional dielectric bodies is proposed. Two problems of plane wave scattering by a dielectric sphere and a thin-wire antenna in close proximity to a dielectric body are investigated. In both cases, cubic modeling is applied and a combination of entire-domain and sub-domain basis functions, including three-dimensional polynomial functions with different degrees is utilized for field expansion inside dielectric bodies. Power polynomial is adopted for this purpose and its property is discussed over the proposed mixed-domain MoM formulation. Numerical examples show that based on the proposed method, a relative fast algorithm and suitable accuracy are achieved compared with conventional MoM. The accuracy of the proposed method is verified by comparing it with the Mie theory, conventional MoM and the FDTD method.

Unwanted electromagnetic emission occurs due to the common-mode current on the cables entering a PC's metal enclosure and can be treated as wire antennas passing through the apertures of the enclosure. To reduce the emission, a stack of metal rings is suggested to be placed around the cable and external to the aperture, adopting the concept of a Coaxial Band-Stop Filter, for the first time. The influence of this novel structure on the common-mode current is examined in the FDTD-method frame work.

Fundamental EMI source that generates common-mode radiation from printed circuit boards (PCBs) is investigated here. It is done by modelling the ground lines of PCBs as imperfect ground. The radiation emission in the far zones from PCBs is obtained by regarding interconnects on PCBs as transmission lines and the far field emission is evaluated based on the current distribution of the lines. The finite size ground trace is defined as an imperfect ground, that can be viewed as an inductive reactance which, in turn, causes the ground return path to radiate as a wire antenna. For the accurate analysis of imperfect ground effect, we divide the equivalent circuit into N sections. In addition, based on transverse electromagnetic (TEM) assumption, we estimate the electromagnetic interference (EMI) of three typical PCB geometries, namely, coplanar strips, parallel-plate strips and microstrips. The quantitative value of induced current distribution along the ground return path depends on the physical size, geometry and length of ground traces. Measured data are presented to confirm the result of numerical analysis. A knowledge of EMI source mechanisms and their relationship to layout geometries is necessary to determine the essential features that must be taken into account to estimate emissions and provide direction for reducing EMI due to interconnects on PCBs.

A new numerical technique, termed the method of matrix-order reduction (MMOR), is developed for handling electromagnetic problems in this paper, in which the matrix equation resulted from a method-of-moments analysis is converted either to an eigenvalue equation or to another matrix equation with the matrix order in both cases being much reduced, and also, the accuracy of solution obtained by solving either of above equations is improved by means of a newly proposed generalized Jacobian iteration. As a result, this technique enjoys the advantages of less computational expenses and a relatively good solution accuracy as well. To testify this new technique, a number of wire antennas are examined and the calculated results are compared with those obtained by using the method of moments.