It is worth increasing height of antenna to bring it above the surrounding obstructions (tall trees, tall houses etc), so that it can “see” the horizon in all or most directions.
Any increase of antenna height beyond this point is very little gain with un-proportionately high cost & effort.
Please first check maximum achievable range for YOUR LOCATION and ANTENNA HEIGHT by the method given in first post of this thread. If you have already achieved it, it is unlikely that you will get any further increase in range by increasing the antenna height.
What is the Maximum Range I can Get?
THEORETICAL BACKGROUND
Overall Range = Contribution of Receiving Antenna Height to Range + Contribution of Transmitting Antenna Height to Range
= 1.41 x √h1 + 1.41 x √h2 miles,
where
h1 = height of Receiving antenna in feet.
h2 = height of Transmitting antenna in feet.
For plane height 45,000 feet, transmitting antenna height = plane height = 45,000 feet:
Contribution of Transmitting Antenna Height to Range = 1.41 x √45000 miles = 299 miles
CASE A - Receiving antenna height = Mast 10’ Above House + House 15’ Above Ground + Ground 39’ AMSL = 64’ AMSL
Contribution of Receiving Antenna Height to Range = 1.41 x √64 miles = 11.3 miles
CASE B - If Receiving antenna height is increased by 10’, it will be 64’ AMSL+10’=74’ AMSL
Contribution of Receiving Antenna Height to Range = 1.41 x √74 miles = 12.1 miles
Increase in range by increasing antenna height = 12.1 - 11.3 = 0.8 miles
Note: Above calculations assume a level terrain without obstructions such as hills, tall trees, tall houses etc.
If the antenna location has above noted obstructions, the range increases considerably when antenna is raised, till it is higher than these obstructions. once at this height, any further increase in height results in little gain at considerable cost & effort.
