Radio Wave Power And How It Gets Reduced By Distance

Introduction

Some people are very concerned that radio wave power coming from radio transmitters’ antennas will harm people. In particular people are troubled by mobile phone masts causing long term health problems when they are near to their homes.

I just want to make it clear how much a transmitter’s power diminishes as it spreads out from a transmitter. I’m sure some feel it must follow a simple linear law such as:

  • double the distance and get half the power,
  • triple the distance and get a third of the power,
  • quadruple the distance and get a quarter of the power.

When in fact it follows an inverse square law which is nonlinear and gives this type of result:

  • double the distance and get a quarter of the power,
  • triple the distance and get a ninth of the power,
  • quadruple the distance and get a sixteenth of the power.

This means the power (and damaging energy) is much lower than might be expected at any particular distance. Even within a short distance the power can drop considerably.

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Terrestrial Freeview TV Aerial Direction

Introduction

In November 2012 I had my terrestrial TV aerial relocated to another corner of my chimney stack so that it doesn’t overhang my solar panels. Birds were perching on it and making a mess on them. Consequently I needed to check my TV aerial direction to be sure it points to the transmitter.

The aerial engineer (Martin Downing) worked until it was dusk when he re-attached my aerial to the chimney stack. That left him little time to adjust my TV aerial direction. I could see from the ground that the initial direction didn’t align with the aerials of my neighbours. I checked the TV picture and on some channels I got interference on my digital Freeview signal causing blocking (corrupt squares of varying sizes) on the picture. So I asked him to rotate it until it matched the other aerials nearby. The picture has been good since.

In this article I show how terrestrial TV aerial direction is accurately set using a compass instead of measuring the signal strength.

I accept that measuring signal strength at the aerial is the best method especially when an aerial is pointing towards an obstruction such as a building or electricity pylon.

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