Okay, lets try to explain a bit better as its not getting through.
Easy scenario - two antennas ten miles apart, installed in the 80’s with a 2G antenna array operating at 900MHz on reach.
Each array has a five mile transmission radius - any further apart than that and 2G no longer works as the signal is too low and they cannot put more power into it as the local schools claim it makes their kids eyes bleed or some other nonsense. All is well, even though getting that small number of towers agreed is a nightmare with every jobsworth in the UK.
Then comes along 3G operting at 1.8GHz which means for the same power output, the cell transmission limit is only 3.5 miles. The new arrays on the old towers now have a dead spot in the middle on 3G as there’s now a 3 mile bit in the middle where the signal doesnt reach. Schools still not keen on kids growing a 3rd ear so no power increase allowed.
So the operator has a choice - install another tower at the mid point and have three antennas all overlapping or instead decide that a 50% increase in infrastructure costs (3 towers vs 2) isnt worth it because nobody in the area makes much in the way of calls. So a gap appears. the locals voted down another mast to fill in the gap.
Then comes along 4G operating at up to 2.6Ghz - cell size is now less than half of what it was and the gaps got bigger. Two or more new sites needed in the middle to provide coverage. Four cell sites needed for contiguous coverage and to make it worse, the links between the cell towers now have to be fibre and the point to point backhaul radio links between them cannot cope with the capacity. Costs go through the roof, so the operator rebadges the cell sites antennas as 4G but leaves the backhaul links as 3G or worse.
You’re getting all techy over the physical antenna array and feeders but that irrelevant - its the phycical tower locations and the power wattage that matter because you cannot fight the laws of physics. 2.6GHz cells are much smaller than 900MHz regardless of the feeders and arrays, and nobody wants to put in additional cell towers in the middle, regardless of the antenna type as its a massive PITA and horrible expensive and time consuming.
Quite apart from the fact that no villager wants to see an extra 2 or 3 large antennas in their village so they can have 4G handsets. Just make the display simply say 4G and they will accept it.
Citiues are easier as here are lots of building tops that nobody can see that you can plaster infill towers onto and fibre is quite easy.
Most towers scattered around the UK out of the bigger cities are still the old 2G sites, with some 3G sites - i worked for a company that was the No2 aerial site owner in the UK for 2G and when 3G was rolled out so i saw these issues first hand.
