__WHY DOUBLING YOUR POWER DOESN’T GET YOUR SIGNAL TO GO TWICE THE DISTANCE__
It’s a popular misconception that the M0 running 100 Watts will be able to work twice as many stations as the 2E running 50 Watts because he/she has double the power.
Here’s why:
If our 50 Watts of power was a single drip of paint we could spread it out to cover a small circle, maybe 5cm in diameter.
How many drips of paint would we need to paint a 10cm circle?
The answer is down to the AREA we need to cover.
The area of a circle is found by Pi (3.142) times the radius squared. (The radius times the radius.)
In the case of the 5cm circle, its radius is 2.5cm.
Its area is 2.5 x 2.5 x 3.142 = 19.6375 square centimetres.
In the case of the 10cm diameter circle its radius is 5cm.
5 x 5 x 3.142 = 78.55 square centimetres – FOUR times the area of the circle that has half of the diameter. This shows we need FOUR times the power to double our signal strength.
This is also why, as you travel away from a line of sight signal if you double the distance the average “field strength” doesn’t half but drops to a quarter.
That is called the “Inverse Square Law”. It also explains why broadcasters don’t normally use just one huge transmitter to cover a country. The power needed to reach all the edges of the country with sufficient strength would be impractically immense so instead they use a number of lower powered transmitters throughout the land. |