Application environment features: in this environment, the business volume is low and users move at high speed. At this time, the focus is on coverage. Generally speaking, it needs to realize belt coverage, so the coverage of highways is mostly two-way community.
Omnidirectional community is also adopted in the areas passing through towns and tourist spots; Thirdly, it emphasizes wide coverage, and the antenna type shall be determined in combination with the selection of station site and station type. Different highway environments vary greatly. Generally speaking, there are relatively straight highways, such as expressways, railways, national highways, provincial highways, etc. it is recommended to build stations beside the highways, using S1 / 1 / 1 or S1 / 1 station type and high gain directional antenna to achieve coverage. There are winding and undulating highways, such as mountain roads and county-level self built mountain roads. It is necessary to select high-altitude stations in combination with rural coverage near the highway.
In the initial planning of antenna selection, the high gain antenna with wide coverage distance shall be selected as far as possible for wide coverage.
Antenna selection principle:
Selection of directional pattern: in the base station that aims to cover the railway and highway, the directional antenna with narrow beam and high gain can be used. The antenna form can be flexibly selected according to the local topographic relief and turning of the road where the station is arranged.
Selection of antenna gain: the gain of directional antenna is 17dbi-22dbi, and the gain of omnidirectional antenna is 11dbi.
Selection of downdip mode: generally, there is no downdip angle for road coverage. It is recommended to select the mechanical downdip antenna with lower price. When the distance is more than 50 meters and there is coverage requirement at the near end, the antenna with zero filling (more than 15%) can be preferentially selected to solve the black problem under the tower.
Front to back ratio: since most users covered by roads are fast mobile users, the front to back ratio of directional antenna should not be too high to ensure normal handover.