What is the disadvantage of 5G mmWave?

There is one major drawback to millimeter waves, though—they can’t easily travel through buildings or obstacles and they can be absorbed by foliage and rain . That’s why 5G networks will likely augment traditional cellular towers with another new technology, called small cells.

Disadvantages of 5G mm wave Millimeter wave goes through different losses such as penetration, rain attenuation etc . This limits distance coverage requirement of mm wave in 5G based cellular mobile deployment. Moreover path loss at mm is proportional to square of the frequency.24 Kas 2019

In humans, MM-waves have penetrating effects including impacts on the brain, producing EEG changes and other neurological/neuropsychiatric changes, increases in apparent electromagnetic hypersensitivity and produce changes on ulcers and cardiac activity .