Antenna downtilt mode can be divided into mechanical downtilt and electric downtilt. Mechanical downtilt antenna tilts the antenna only when it is erected, which is cheaper and is mostly used in the environment with downtilt angle less than 10 °. electronic downtilt antenna is expensive, and its downtilt angle range is large (more than 10°). When the downtilt angle is large, the antenna pattern has no obvious distortion, and the antenna back lobe will also be downtilt. For the case that the downtilt angle is large, the fixed electric downtilt antenna with small angle plus mechanical downtilt scheme is often adopted. The dip angle is measured by a slope meter.