CHAPTER 3
Microwave Line-of-Sight Systems
3.1 ENGINEERING OF LINE-OF-SIGHT SYSTEMS
3.1.1 Introduction
Microwave radio systems are regarded as line of sight when the waves transmitted between the two stations do not meet any obstacle most of the time. In the engineering phase of this type of microwave radio link, it is advisable to take account of the following factors and dominant effects of propagation which have been treated in preceding chapters:
- Attenuation by diffraction due to obstacles on path which block the way under conditions of subrefraction (Kmin)
- Absorption by gases of atmosphere
- Absorption by solid particles in atmosphere
- Attenuation and depolarization by hydrometeors (e.g., rain, ice crystals)
- Fading imputable to multipath, reflection on ground, or ducting under conditions of superrefraction (dN/dh < −100 N km−1)
- Amplitude–phase distortion of signal due to selective fading and propagation differential time delay in event of multipath, reflection, or ducting conditions
- Vertical variation of launch and arrival angles of rays at antennas due to changes in vertical refractivity gradient
- Jamming by other radio links of network which share same frequency plan and polarization or by other external sources of emission
3.1.2 Establishment of Radio Link Path Profile
This ...
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