A Design of Vehicular GPS and LTE Antenna Considering Vehicular Body Effects

Patchaikani SINDHUJA  Yoshihiko KUWAHARA  Kiyotaka KUMAKI  Yoshiyuki HIRAMATSU  

IEICE TRANSACTIONS on Communications   Vol.E99-B    No.4    pp.894-904
Publication Date: 2016/04/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.2015EBT0002
Type of Manuscript: PAPER
Category: Antennas and Propagation
vehicular GPS and LTE antenna,  wire antenna,  pareto genetic algorithm,  commercial electromagnetic simulator,  

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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.