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Over-the-Horizon Radar
Published in Habibur Rahman, Fundamental Principles of Radar, 2019
The performance of JORN2324 is heavily influenced by the ionosphere containing ionized particles. It is responsible for bending the electromagnetic waves back to the earth making skywave propagation possible. The ionization level in the ionosphere depends on solar energy and extreme space weather conditions caused by lightning and thunderstorms. The ionization is also correlated with the number of visible sunspots, solar flares, coronal mass ejections (CMEs) and geomagnetic storms distracting HF skywave propagations.
Wireless Transmission Mediums
Published in Mário Marques da Silva, Cable and Wireless Networks, 2018
Skywave propagation consists of successive refraction in the ionosphere layers and successive reflection in the earth’s surface. This can be seen from Figure 5.18. In fact, according to Snell’s law, the gradual and successive refraction in the ionosphere layers can also be viewed as a reflection phenomenon.
Radio Wave Propagation
Published in Jerry C. Whitaker, The RF Transmission Systems Handbook, 2017
The representation of the radio wave path in Fig. 15.3 and the previous discussion have only considered a direct path between the receiver and transmitter. In reality, there are two major modes of propagation: the skywave and the groundwave. The skywave refers to propagation via the ionosphere, which consists of several layers of ionized particles in the Earth’s atmosphere from approximately 50 to several hundred kilometers in altitude. Some frequencies will be reflected by the ionosphere resulting in potentially long-distance propagation. This propagation mode is discussed in detail in a later section.
Ionospheric delay estimation of Loran skywave using simple cosine model
Published in Electromagnetics, 2023
Kai Zhang, Fan Yang, WeiDong Wang, Chen Zheng, Borong Zou, Hui Li
There are four components of the skywave delay. Except the delay of skywave signal on the propagation path, the other three are error correction items in the propagation process. The first term is the error of receiving and transmitting antenna factors. It is due to the influence of the curved earth on vertical radiation pattern when antenna is close to the ground. The antenna factor is affected by the signal frequency and position. It is calculated for land, sea, and ice conditions, which are defined by their electrical characteristics (conductivity and permittivity) and usually changed little in Loran receiving system. The second term is the ionospheric focusing factor. The ionospheric reflection model is equivalent to planar reflection, but the actual ionospheric is curved. Therefore, the ionospheric focusing factor is used to represent the change of wave propagation law. This error has small value and gentle variation, which is affected by signal frequency and time. The last term is error effect of the skywave passing through the ionosphere, which is expressed by the equivalent ionospheric reflection coefficient. This is also the most important variation of the propagation delay of the whole skywave path.