Propagation of radio waves with a wavelength of 10-1 m (corresponding frequency of 30-300 MHz) through the ionosphere
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Ultra short wave propagation refers to the propagation of radio waves with a wavelength of 10-1 m (corresponding frequency of 30-300 MHz) through the ionosphere.
Ultrashort wave ionospheric propagationThere are two main forms of scattering propagation and transmission propagation.Since 1950, HG. Booker and WE. After Gordon put forward the theory of ultrashort wave tropospheric scattering propagation, P.K. Bailey and others used high-power transmitters and highly sensitive receivers to carry out the ionospheric ultrashort wave scattering propagation, and established ultrashort wave, over the horizon, and low ionospheric scattering communication circuits, with the communication frequency of about 30-60 MHz.
Scattering mechanism
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This scattering mechanism is based on theIonospheric inhomogeneityThe communication distance is 1000~2000 kilometers, which is suitable for cross regional or inter island communication.The biggest feature of this communication mode is thatIonospheric disturbanceIt is especially suitable for use in high latitude areas and across auroral regions.However, the communication capacity is low. Generally, only one telephone or four frequency shift telegrams can be connected. Moreover, compared with short wave equipment, it is bulky and expensive.1957Artificial earth satelliteLaunch successful.It can use ultrashort wave ionospheric transmission mode as an important channel for communication between space flying body and ground.This transmission mode has the ideal frequency window required by the space flying body telemetry and telecontrol system.At the same timeionospheric sounding Research provides a new means.In the transmission mode, in order to ensure the high-precision positioning and tracking of the space flying body, it is necessary toIonospheric refractionThe error is corrected.In addition, the ultrashort wave navigation satellite uses two coherent frequencies to eliminate the Doppler frequency shift caused by the inhomogeneity of the ionospheric medium, so as to improve the navigation accuracy.
