| The U.S. GPS (Global Positioning System) has been one of the best In the field of satellite navigation and its characteristic frequency of the satellite positioning is1575.42MHz. GPS is a new generation space satellite navigation system jointly developed by the U.S. armed forces in the1970s. Its main purpose is supplying real-time, weather and global navigation services for land, sea and air areas, and the info is used in intelligence gathering, nuclear explosion monitoring, emergency communications and some other military purposes, moreover it’s an important component of US’s strategy to dominate the world. After20years’research and experiments at a cost of$30billion,24GPS satellite constellations, which up to98%of global coverage has been laid completely in March1994.The development trend of modern electronics industry is smaller, lighter and thinner. And the formacompleteset electronic components are also subject to the challenges of this market-oriented. The navigation modules are playing prominent role in modern life increasingly. According to national strategy, the acceleration of urbanization and the booming auto industry, vehicle positioning and3G mobile phone GPS navigation function is more and more important in contemporary life. Facing the market demand pressures, it’s increasingly urgent to solve functional components navigation antenna miniaturization issues currently.Microwave microstrip antenna is an antenna with a conductor sheet posted on the dielectric substrate. It froms the radio-frequency electromagnetic field excitationuses by microstrip lines or coaxial lines, and radiates externally through the gap between four sides and ground. Therefore, the microstrip antenna can also be set as a gap antenna. Typically, the thicknes of dielectric substrate is smaller compared with the wavelength, so it implements the one-dimensional miniaturization and it’s a type of electrically small antennas. Advantages and disadvantages of microsirip antennas and applications(1). thin profile, small size, light woigh: (2), has a planar structure and can be made to missile, satellite and such carrier surface with conformal structure;(3), feed network can be made together with the antenna structure and suitable for mass production of printed circuit technology;(4), can be integrated with the active devices and circuits to a single appearance;(5), easy access to circular polarization and multi-functional work such as dual-band, dual-polarizedThe main disadvantages of microstrip antennasare:(1), narrow band;(2), has conductor and dielectric loss, and will encourage surface wave and result in lower radiation efficiency;(3), power is smaller, generally used for medium and small power applications;(4), performance is mainly affected by the substrate material... |
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