The Fundementals

Introduction Maxwell's equations Plane waves Free space loss Gas Loss Refraction Diffraction Reflections Troposcatter Rain effects Vegetation Statistics Link budgets Noise Multipath Measurements Models



An introduction to radiowave propagation

Course notes

© Dr Mike Willis 2007


This course deals with how signals get from a transmitter to a receiver

We will cover the fundamentals first:

  • EM Waves
  • Line of sight paths
  • Non line of sight paths
  • Variability with time and space

Apply to systems - Mobile, Terrestrial microwave links, Broadcasting, Satcoms:

  • The channel characteristics
  • Models for prediction of effects

Why it is important to understand propagation

The radio spectrum has a large range of applications in many operational environments. The frequency bands cover many orders of magnitude in frequency. Radio systems require transmitting sources and receivers to provide wireless communications links. Understanding the radio channel between the transmitter and the receiver is critical in designing any radio system.

Service providers for example broadcasters, private radio users like taxi firms, mobile phone network operators, the MOD and a host of others all want to know how to get radio coverage for their particular application. When planning a service they need to know where to put their masts, how many masts will be needed, what antennas should be used, how much transmitter power is going to be needed and how reliable their radio links will be.

Regulators who manage the radio spectrum are interested in making the best use of this limited and valuable resource. They need to regulate so that as many as possible can share the radio spectrum and so are interested in predicting interference between users. Where do signals go beyond where they are intended to. Also what is this or that bit of spectrum worth and how much benefit can the taxpayer gain from selling the rights?

It is frequently forgotten how important propagation is to the overall performance of a communications network. Radiowave propagation studies allow us to estimate and evaluate the radio channel and so design systems that work as well as possible. Some people, especially the regulators may prefer propagation to be simple, but in practice propagation is fairly complicated, so we will start with the fundamentals….



© Mike Willis May 5th, 2007