天线知识（Antenna knowledge）.doc

天线知识（Antenna knowledge） Antenna knowledge First of all know radio communication mode: Surface spread: Just stick the surface spread outward scattering, Its characteristic is more stable signal, The main mode of transmission. For long wave and wave wave period. Three Mhz. Sky wave propagation: In the atmosphere, From a few tens of kilometers to hundreds of kilometers altitude has several layers The ionosphere The formation of a natural The reflection waves shot The ionosphere It will be reflected back, go this way is called the sky or wave reflection. stay The radio, mainly in the short wave with such characteristics. 3-30 Mhz. Scatter propagation: Is the use of medium troposphere or ionosphere in inhomogeneous or through the atmosphere when the meteor ionization trails of electricity Scattering of magnetic wave to achieve super moment propagation. This mode of transmission is mainly used for ultrashort wave and microwave remote communication. 30-500 Mhz. Line of sight: waves directly from the transmitting antenna to receiver point ( Sometimes a ground wave ) . The widely used short Wave communication and satellite communication radio propagation is this mode of transmission. 2.4G To control 5.8G Pass in the VHF range. For the needs of real-time control of model airplane, In addition to receive direct letter, To improve the properties of any outside by radio The distance is not reliable, although long wave diffraction ability is extremely strong, still affected by the space environment, is not stable. [radio Penetration ] radio frequency is high, the more close to the propagation characteristics of light, radio penetration of insulator, The reflection and diffraction of conductor. I often say that the penetration, in fact, most of the time, friends want to pursue the diffraction ability, The low frequency diffraction ability is stronger, on the radio, actually use its diffraction capability of the band is long wave and medium wave, that is Three Mhz. stay Thirt