In order to track and identify remote cargo with electronic label, the electronic label may carry GPS module. To GPS modules antenna, not only the factors such as impedance bandwidth and axial ratio bandwidth are considered, but also the stability of the phase center is more concerned about, due to it determines the precision and accuracy of location. At the same time it requires that axial ratio is less than 3 db in wide angle range of elevation theta. Realizes circular polarized GPS antenna through the orthogonal 4-fed mode and Wilkinson power splitters, in addition, calibrates and optimizes the average phase center of antenna through the optimization algorithm. The simulation results show that GPS antenna works in the L-band 1.575 GHz,impedance bandwidth in which return loss less than-10 db achieves 91.4 MHz,and coverages: 1.5358 ~ 1.6272 GHz; 3db axis ratio bandwidth achieves 305 MHz in the biggest gain direction of XOZ section;In the center frequency point 1.575 GHz, elevation theta which corresponds 3db axis ratio coverages: -119.2°to 111.5°; The stability of the phase center is less than 3 mm.
VLC Electronic Label for Hypermarket
