Research Of Circular Polarization Antennas In Satellite Navigation Position Systems

After decades of development, the satellite navigation technology plays an important role in modern information industry. As the key component of navigation position system, the antenna will affect the performance of the whole system. And it also needs some special performance in this application. Therefore, it is necessary to study the antennas used in satellite navigation position systems. Based on this background, the circular polarization antenna technology, dual-frequency microstrip antenna technology, and the method of broadening the beamwidth and increasing the low elevation gain are investigated.A dual-band circular polarization microstrip antenna is designed and fabricated. The antenna can operate both in the L and S band with the double overlapped structure and its two-point feed structure ensures that the antenna achieves good circular polarization performance. The experimental results show that in the whole work band, the axial ratio of the maximum radiation direction is less than 2dB, the 3dB beamwidths in L and S band are 97 o and 90 o respectively, and the gain at the elevation angle of 10o is greater than -3dB, which meet the design specifications. The proposed antenna is easy to fabricate for small batch production.In order to broaden the 3dB beamwidth, a three-dimensional ground structure is introduced. By adjusting the upper radius, the lower radius and the height of the ground structure, the beamwidth and low elevation performance can be improved. Resarches show that when the radius of the upper floor equals 37 mm , the lower floor equals 60 mm and the height equals 30 mm, the 3dB beamwidths in L and S band are 116 o and 108 o respectively, the gain at the elevation angle of 10o is more than -2dB.A dual-band wide beamwidth vehicle antenna is studied in this paper. This antenna broadens its L band beamwidth by means of a three-dimensional ground structure, and a metal bracket in the upper plate is added to broaden S band beamwidth. Experiments show that the 3dB beamwidth in L and S band are 156 o and 127 o respectively, and the gain at the elevation angle of 10o is more than -2dB.To broaden the 3dB beamwidth in S band, a crossed dipole is introduced into the vehicle antenna to replace the patch of S band. By tuning four inclined angles of the arm, the 3dB beamwidths in L and S band are 152 oand 103 o respectively and the gain at the elevation angle of 10o is more than -0.5dB.