In general, when the size of the antenna unit is half a wavelength, the efficiency is the highest. Therefore, the shorter the wavelength of the electromagnetic wave, the smaller the required antenna unit. The higher the frequency, the shorter the wavelength of the electromagnetic wave, and the smaller the required transmitting and receiving antenna unit. The characteristic of mmWave is that the wavelength is short, so the size of the antenna can be small, and the mmWave base station can accommodate more antennas in the same area. When there are many antennas, they are densely arranged in a square array to form an antenna array.
By adjusting the weights of multiple antennas on the antenna array, the energy of the signal can be concentrated, just like a flashlight aimed at the mobile phone for precise coverage, which is beamforming. The higher the frequency, the more the number of antennas, and the better the shaping effect. The beamforming ability depends on the number of antenna elements. The more the number, the narrower the beam, the more concentrated energy of the beam can be aimed at users, which improves coverage and avoids interference, thus the shaping effect will be better. At present, the number of antenna units integrated into the mainstream millimeter wave AAU has reached 512 or even 768. It is believed that it will not be long before 1024 antennas can be plugged. Because of the blessing of beamforming, the narrow beams of the 5G NR mmWave can concentrate energy, accurately align and track the user's movement, bringing a better user experience and reducing interference.
The mmWave can also support high-precision positioning. With the properties of beamforming, narrow beam, good directivity, and extremely high spatial resolution, and small-time delay, mmWave can achieve ultra-high-precision positioning.