Cellular Power Densities

Not sure were to obtain 4 & 5G specs in which there would be detailed minima and maxima power requirements for coverged serviced area.

Is anybody familiar with their min&max power densities?

If 5G really is 24-86 GHz then there needs to be antennas everywhere or the service providers will need to spend lots on high power semis in their towers as those frequencies are prone to being absorbed even by the constituents in ambient gasses and more so by vegetation and other solid matter.

The 5G phase 2 specs (mmWave) are still under development and will be completed in June 2020:

https://www.3gpp.org/release-16

Should't the emphasis of mobile phones be maximum reliability with minimum infrastructure?

The bands 5g works with has nearly always been employed for point to point communications or used for beam steering for radar applications.

I think that "maximum reliability with minimum infrastructure" is the target of any wireless system, not only of the cellular systems.

They can reduce infrastructure if the frequency was further reduced. A few hundred Mhz should be enough to transmit great distance without the need to saturate the cities with cell towers - which 5G spec will have to do in order to maintain its absurd frequency band.

Totally agree. To make a cellular system working (decent) at 39GHz perhaps have to go back in time and ask Maxwell and Hertz to invent things other than those with which they made history.

What are the current permissible power densities for the 4G spec within the coverged service areas?

Also - maximum reliability with minimum infrastructure does no longer apply for the 5G cellular infrastructure since the quantity of antennas is likely to have a quantity constantly under repairs whilst allocating its load to the other antennas in the vicinity which will likely render them inoperable perdue the higher loads.

Yes, trees will totally block signal at 24GHz, just one layer of leafs in the beam is enough to absorb/reflect most of it. Another problem is that higher frequencies are modulated when reflected by various electrical devices (containing diodes, transistors, air conditioning fans, gas discharge lamps etc.). Similar situation with traffic radars. Small insect / piece of dirt may block significant area of 77GHz radar antenna. There are some benefits from higher frequencies, but there are still many question. Maybe microwave chip manufacturers are pushing for higher frequencies to prevent smaller companies from entering the market.