| In now days, the full or partial operation of the global navigation satellite systemincludes mainly the United States GPS, Russia’s GLONASS, European Galileo systemas well as China’s Compass II system. The spectrum of GNSS carrier signal spreadacross1164-1278MHz and1559-1610MHz. Multimode satellite navigation technologyhas been a hot study topics in satellite navigation due to it can improve the positioningprecision, reduce to the dependence on a single system, improve reliability.Anti-multipath technique can enhance the system’s ability to adapt to differentenvironments and improve the precision. It also became an important title.This paper aims to provide a design idea of multimode anti-multipath satellitenavigation antenna. The antenna is based on a double-layer circular microstrip patchantenna, using capacitive probe coupled feeds to broaden bandwidth of the twofrequency bands. The four-point-fed method, to provide good electrical symmetry, cangreatly optimize circular polarization performance. Lossy ground technique is adoptedto provide good multipath suppression capability.To realize the four-point-fed, a broadband feed network with four output ports isneeded. The feed network provides four consistent amplitude with the relative phase of0、90、180and270, respectively. A gradual resistive plate made of the filmwith sheet resistant, is applied to absorb antenna surface wave, reduce backlobes andenhance the multipath suppression capability.After experimental verification, aerial superiority is reflected in the followingaspects: first, the wide frequency bandwidth can cover all the GNSS bands. Second, thehomogeneous radiation provides roundness of less than1.5dB, gain of20elevationgreater than-3.5dB. Third, circular polarization performance is good, with the vertexaxial ratio better than1.5dB,20elevation axial ratio greater than4dB. Fourth, the highperformance multipath suppression，provides about30dB front back polarized gainratio. |
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