An Assessment of Pulse Dispersion in Ionospheric Propagation Channels

• Main Author: 楊展昇
• Other Authors: 林根煌
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/16081071357522565517

碩士 === 國立中山大學 === 電機工程研究所 === 85 === Ionospheric propagation, unlike the line-of-sight path which is limited by the curvature of the earth, is capable of long-distance communication. The propagation mode is known as the sky wave. It is found that the HF band (3-30 MHz) is particularly suitable for the ionospheric propagation. In this band, the properties of the ionosphere dominates the characteristics and quality of the channel, among which the dispersion is most noticeable. The ionospheric dispersion has been studied by assuming a quadratic phase channel. Other attempt using the ionospheric transfer function has also been carried out. In the thesis the effect of the third-order derivative of the phase with respect to the carrier frequency is included. In addition, the influence of the possible horizontal gradient of the electron density is also studied. It is found that the quadratic phase channel assumption is adequate under practical situations.