Whether it is a transmitting antenna or a receiving antenna, they always operate within a certain frequency range (bandwidth), and the bandwidth of an antenna has two different definitions------
One refers to the operating bandwidth of the antenna under the condition of a standing wave ratio SWR ≤ 1.5;
One refers to the bandwidth within a range of 3 decibels when the antenna gain decreases.
In mobile communication systems, it is usually defined according to the previous one. Specifically, the bandwidth of an antenna is the operating frequency range of the antenna when its standing wave ratio (SWR) does not exceed 1.5.
Generally speaking, there are differences in antenna performance at various frequency points within the working bandwidth, but the performance degradation caused by these differences is acceptable.
