lanning Medium Haul The frequency of operation of these links is usually from 11 GHz to 20 GHz. Depending upon the climatic conditions and frequency of operation, the hop length can vary between 40 km and 20 km. These links are also affected by multipath fading and rain fading. Frequency band 13 GHz Maximum path length about 40 km Multipath fading Antenna diameters 60-120 cm for a gain range of 36.4-42.4 dB Both vertical and horizontal polarisations used Frequency band 15 GHz Maximum path length about 35 km Multipath fading Antenna diameters 60-120 cm for a gain range of 38-44 dB Both vertical and horizontal polarisations used Frequency band 18 GHz Maximum path length 20 km Rain and multipath fading Antenna diameters 60-180 cm for a gain range of 39-49 dB Both vertical and horizontal polarisations used Atmospheric attenuation 0.1 dB/km. Attenuation due to rain about 1 dB/km at a rain rate of 20 mm/h Short Haul These links operate in high frequency ranges (23-58 GHz) and thereby cover shorter distances. At lower frequency ranges in this band, links are affected by both multipath and rain fading. At higher frequencies, when the hop length is only a few kilometres, the multipath phenomenon does not have a significant effect. However, the impact of rain is quite severe. Frequency band 23 GHz Maximum path length about 18 km Rain and multipath fading Antenna diameters 30-120 cm gain for a gain range of 35.5-47.3 dB Both vertical and horizontal polarisations used Atmospheric attenuation 0.1 dB/km Attenuation due to rain about 3 dB/km at a rain rate of 20 mm/h Frequency bands 26 and 27 GHz Maximum path length is about 15 km. Rain fading Antenna diameters 30-60 cm Both horizontal and vertical polarisations used Atmospheric attenuation 0.1 dB/km Attenuation due to rain about 3 dB/km at a rain rate of 20 mm/h Transmission Network Planning and Optimisation Frequency band 38 GHz Maximum path length about 10 km Rain fading Antenna diameter 30 cm for a gain of 39.66 dB Only vertical polarisation used Atmospheric attenuation 0.1