Research On Cross Dipole Antenna Applied To Satellite Navigation Terminal

As an important part of the satellite navigation system,the performance of the antenna directly affects the communication quality of the entire navigation system.Cross dipole antennas have been widely used in satellite navigation systems because of their good circular polarization,high low-elevation gain and wide bandwidth performance.In this paper,a wideband high and low elevation gain cross dipole antennas are studied.The works and research contents are as follows:1.An antenna with wide bandwidth high low-elevation gain for satellite navigation terminal is studied.The antenna consists of two pairs of crossed dipole antenna arms,a feed network and Fence-shaped reflection cavity;two pairs of crossed dipole arms are located on the horizontal plane and the vertical plane respectively,forming an effective contribution to the gain in the elevation directions of the upper half space.The phase difference of 90 degrees is realized by using the feed network to satisfy the circular polarization condition of antenna.Fence-shaped reflecting cavity is used to realize the directional radiation and improve the antenna bandwidth and low elevation gain.The influence of typical parameter variations on antenna performance is analyzed.The test results show that the impedance bandwidth of antenna|S₁₁|≤-10d B is 1.330-1.810GHz,the axial ratio bandwidth of less than 3d B is 1.54-1.66GHz and the maximum gain of 10^olow elevation at frequency of 1.561GHz,1.575GHz and 1.602GHz is 0.35d Bi,0.21d Bi and 0.1d Bi,respectively.The antenna has high low-elevation gain,relatively small size and wide bandwidth.2.A cross dipole antenna with compact and high low-elevation gain is proposed.The antenna consists of bend crossed dipole antenna arms,parasitic patch,shorted metal column,bending cavity,and slotted reflective plane.On the basis of the previous chapter,the effective current path of the surface current of the dipole arm is extended by coupling the bent dipole arm with the circular parasitic patch,and the device miniaturization is realized.The low elevation gain and directional radiation performance of the antenna are improved by introducing T-slot in the bent cavity and slot in the bottom plate.The test results show that the antenna has a impedance bandwidth of|S₁₁|≤-10d B,which is 26.63%（1.299-1.698GHz）with the axial ratio 3d B bandwidth of 9.26%（1.493-1.638GHz）and the maximum gain of 5^olow elevation at frequency of 1.561GHz,1.575GHz and 1.602GHz is 0.40d Bi,0.28d Bi and 0.38d Bi,respectively.The antenna has high low-elevation gain,relatively small size,better bandwidth,and directional radiation3.In this study,a compact wideband crossed dipole antenna for global navigation satellite system（GNSS）applications is proposed,which consists of the cross-dipole arm,parasitic patch,shorted metal column,and卐-shaped reflecting plane.The circular polarization bandwidth of the antenna is improved by using multiple parasitic patches coupled with the cross dipole arm on the basis of the previous chapter slotted reflecting surface.The proposed antenna has an overall dimension of 0.37λ₀×0.37λ₀×0.12λ₀（λ₀is the free-space wavelength at center frequency）.The measured|S₁₁|≤–10d B and AR<3d B bandwidth are from1.095-1.745GHz（45.77%）and 1.12-1.675GHz（39.71%）,respectively.The proposed antenna can fully cover the band of GNSS with small size and better directional radiation.