A. A. Gavrilov, O. A. Kurdjumov, V. E. Sagatch, S. K. Krylov

This article contains review of modern precision global navigation satellite systems (GNSS) positioning antennas and description of different types of their conventional design. In this work you can also find classification of antenna multipath mitigation devices and modern trends in GNSS precision positioning antennas - development. Navigation systems, having less than 30-cm positioning accuracy, can be named high precision. Antennas, that are used in such a receivers are also named high precision or having "stable phase center". The purpose of these antennas is the GNSS signal receive and reduction of positioning errors. The multipath effect is the main source of positioning errors. Negative influence of this effect appear when receiver's input get not only direct satellite signal, but also signal, reflected from ground surface and nearest objects. The main method of multipath minimization - is the correct shape of amplitude radiation pattern (RP). Besides multipath effect there is another influencing factor, that makes positioning accuracy worse. This factor represent dependence of signal-s phase from angle of wave incidence that depends only from antenna-s properties. There are also technological troubles in serial production. These antennas need to have the identity of phase and electrical characteristics from one sample to another. Antenna module of navigation receiver can be subdivided on two pieces: 1 - receiving module, containing patch-antennas, that provide a right hand circular polarized signals in GNSS bands (L1,L2,L3 - GLONASS; L1,L2,L5 - GPS Navstar; E1,E5a,E5b,E6- Galileo; B1,B2,B3 - Compass) and low noise amplifier (LNA). 2 - Multipath suppression device. Below there is a description of various realizations of high precision antennas for reception of GNSS signal. One of the most wide spread solution of GNSS signal reception for high precision positioning is the usage of antennas, established on various "choke-ring" modifications. As usual microstrip antennas (MSA) are used as a passive patch. MSA are established in the center of "choke-ring". Another variant of high precision antenna-s construction is a small-size antenna array. Circular antenna array of spiral stripes or slots, that are illuminated by special feeding network, can be shown as an example. RF absorbing material is placed on the screen walls to prevent wicking of current flow, caused by multipath effect. Further one can find variants with placement of antenna elements (single MSA or antenna array) on horizontal "choke-ring". Horizontal "choke-ring" differs from classical one, because it has quarter-wave slots, that are placed in horizontal plane. Some solutions use the screen with a patch, placed in the center, made of material with resistive loss. We can also find multipath suppression systems based on fractal screens or EBG (Electromagnetic Band Gap) structures. ЕBG structure - is a high impedance surface, that prove a counter-phase summing of multipath currents. Operating principle of fractal screens are similar with arrays of passive chopper. Passive antenna-s elements are placed on the central surface on the screen. One more way of high precision antennas construction - establishment of antenna elements on supporting plate, made of artificial dielectric, realizing high-impedance surface. The further spread of high precision antennas development - reduction of mass and dimensions parameters and combination of navigation and additional devices in the same case. In antenna-s designing the ability to work in frequency ranges not fully spread out in GNSS should be kept in mind.