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How to Calculate the Maximum Distance of LOS Coverage in
known Tx Height By Justin MA
Created: 2015_0524 Updated: 2015_0525
What is the maximum LOS distance of a radio tower?
Ref: hill: http://misteraibo.deviantart.com/
Ref: Radio tower: http://www.szoges.com/
The Height of Radio tower：H1 m
The altitude of hill：H2 m
Sea level
D km =?Ref: Question man: http://www.foodcentral.com.au/
Assumption: Without regard to the power issue
Assumptions
• Transmission is isotropic.
• There is no limitation of transmission power.
• Only focusing on the LOS coverage.
So, what is the limitation now?
Ref: Question man: http://www.foodcentral.com.au/
LOS is stopped here!
The Earth is a ball
Descriptions
• The earth surface is round.
• The LOS of ray will travel until it touch-down the farest point on the earth surface.
So, let’s calculate it now!
Radius of the earth：6371km
Height of tower + Altitude：H mMax. LOS distance：D km
Calculation:
D^2 + 6371^2 = (6371 + H)^2D^2 = (6371 + H)^2 – 6731^2D^2 = (6371 + H + 6731) x (6371 + H - 6731)D^2 = (2 x 6371 + H) x HD^2 = 2 x 6371 x H + H^2
General Calculation of maximum distance of LOS
Example: What if Tx is on top of Taipei 101
The Altitude of Taipei 101: 508m
Ref: http://zh.wikipedia.org/
Taipei 101
What is the maximum LOS distance of a radio tower on Taipei 101?
Sea level
D km =?
Assumption: Without regard to the power issue
Ref: http://zh.wikipedia.org/
508 m
Height of tower + Altitude： 508 m
D^2 = 2 x 6371 x 508 + 508^2D = 80.5 km
Calculation of maximum distance of LOS for Taipei 101
Max. LOS distance：D km
Radius of the earth：6371km
The maximum distance of LOS for Taipei 101
• It is about 80.5 km
• Now we learn how to calculate the maximum LOS coverage of a known height radio tower with the local altitude.
