What are the advantages and challenges of using mmWave frequencies for beamforming?

mmWave frequencies start at approximately 30 GHz and go up to 300 GHz, corresponding to the mentioned wavelengths between 1 and 10 mm. Increased frequency allows for a higher absolute bandwidth, a crucial factor for higher data rates and in RF components where fractional bandwidth is often a limiting factor. Nevertheless, the trade-off of going up in frequency includes higher free space path loss and increased attenuation in materials.

Beamforming on mmwaves is not so much of a "perk" but more of a necessity. We need to get as high gain as possible to compensate for significant path losses

As we go higher in frequency, the path loss and atmospheric attenuation increases drastically. Issues like multi-path fading and low diffraction rate can worsen the network quality. Beamforming can resolve most of these issues by focusing most of the RF power in one direction.

The mm-wave frequency band provide large bandwidth. Attractive channel capacity and spectral efficiency can be achieved through beamforming techniques.

Originally Beamforming, is a byproduct of WWII radar development against enemy air-raids. Then and nowadays, it is a physical-phase grouping of radiating element to concentrate power in a given direction to improve gain and efficiency. This is necessary in mmWave and Sub-THz band because their path-loss is high. When propagation loss is high, one might as well concentrate power where it is useful, rather than wasting it all around. This is the case for mmWave and sub-THz frequency bands

When you have a grid or radiating elements (antenna) organized efficiently (lambda/2 appart), then you can shift each element phase such that the resulting combined energy, propagates in a direction which is not necessarily normal. In other word, you take 2 stone in you hands and throw them in a lake at the same time, the resulting wave peak is normal to where the stones landed. if you send them with a slight off phase timing, then the resulting peak of the combine wave is shifted side ways. This is beamforming. when you have many phase-shifted radiated elements you can accurately predict the direction of propagation in 3D. i.e. for mmWave concentrate the radiated energy between transmitter and receiver, to improve link efficiency.

Popular ways of beamforming are by using antenna arrays and leaky wave antennas. Highly directional antennas could achieve focused beams. Using thicker substrates may result in focusing the beam but due to the losses in the substrate, the gain may well get reduced.

Beamforming advantages: - Increased SNR - Increased channel capacity - Increased distance - Decreased power consumption - Increased precision

The obvious advantage of beamforming is that it results in a more direct communication between a transmitter and a receiver. This boosts the power of EM waves by concentrating them in a single beam, thus extending the travel potential of a signal (which is critical for mmwave to overcome path loss and absorption). It also helps reduce RFI from surrounding EM radiation from other sources because signals are directed toward defined and targeted areas. It also supports next-gen technologies such as augmented reality, virtual reality, massive IoT and autonomous vehicles.

ultimately, the only advantage of beamforming is the spacial concentration of energy. everything else is derived from this, but the implication are vast on so many level. Most notably, high frequency bands which were once believed unusable with typical antenna arrangement, can now be used efficiently and provide exceptional bit/watt performance, only possible thanks to beamforming techniques.

In present situation where antennas are radiating with widebeamwidths, many unintended subjects are exposed to RF radiations and high SAR levels. Beamforming and beamsteering combinely can help mitigate the RF exposure as the RF energy will be directed towards the intended receiver only.

But highly susceptible to the absorption from obstacles like building etc. And the lower coverage area. These are the biggest challenges faced by mm wave.

Heat dissipation is one more important thing to keep in mind when implementing beamforming on mmwaves. Thermal analysis is essential to perform in order to get a functional design.

The challenges associated with it is the physical coverage of the base-station in wireless communications reduces drastically, and hence it needs to be coupled with multi-beam-steering, which can be power hungry. A lot of research is being done in developing new beamforming and beam-steering techniques to maintain low power and high efficiency.

I agree with @Katerina Galitskaya, heat dissipation is a factor that isn't addressed in most cases. At mm wave size of antenna is smaller and the surface for dissipation of heat is lower. Initial studies have shown heating issues have impact on realability on RF performance that every 10 degree temperature reduction increases RF components reliability by 50 percent. I myself had studied and investigated during my master Thesis with a simple heatsink antenna structure (28 GHz) with different fins on top of Microstrip patch antenna. Thermal simulation results showed 10-20 degree Celsius reduction for such arrays while maintaining or improving the EM performance.

Beam steering scan range is limited by the use of phase shifters. New innovations to increase scan ranges are need of the hour.