Radio Signal Propagation

- concise guides, information and tutorials to radiowave propagation including topics such as HF radio propagation, VHF propagation, microwave radiowave propagation, the ionosphere, ionospheric propagation, etc. Also overed is the effect or radiowave propagation on general radio communications, two way radio communications, mobile radio communications, radio broadcasting, cellular telecommunications coverage and Wi-Fi propagation.

The way in which radio signals travel or propagate it is prime importance to anyone associated with radio communications, be it cellular telecommunications, HF radio communications, two way radio communications, maritime or general mobile communications and much more. From radio communications users of the short wave or HF bands through to those using the VHF and UHF bands. Radiowave propagation is also of great importance to those using satellites, whether for TV reception, GPS or for any other purpose. Although satellites use frequencies well above the limits normally though to be affected by the atmosphere, there are still radio signal propagation effects that are noticed. Additionally radiowave propagation is very important to those planning radio communications networks, from cellular telecommunications or PMR networks, through to those using WiFi and other wireless technologies including Bluetooth, Zigbee, and Wimax.

Radio signal propagation basics

Radiowave propagation changes with frequency, and also with a number of other aspects. Whatever the frequency, radio waves are a form of electromagnetic wave and obey the basic laws that govern this type of wave. In order to understand how radio waves propagate it is necessary to look at the basic properties of electromagnetic waves and also the medium in which they travel, i.e. the atmosphere.
Electromagnetic waves and the electromagnetic spectrum
Reflection, refraction and diffraction of radio signals
Polarisation of electromagnetic waves - and their importance in radio wave propagation
Areas of the atmosphere that affect radio signals
An overview of the different types of radio propagation

Ground Wave

The ground wave is an important form of radio signal propagation. It is used by radio communications and broadcast stations on frequencies below about 2 MHz and enables them to provide local coverage.
Ground wave radio signal propagation

Ionospheric radiowave propagation - types of propagation and basic principles

Signals in the LF, MF and HF portions of the radio spectrum can travel over great distances using ionospheric propagation:
The Ionosphere
Ionospheric propagation
Ionospheric radio signal absorption
Critical frequency, MUF and LUF
Sporadic E
Transequatorial propagation
Near Vertical Incidence Skywave, NVIS, propagation

The Sun

The Sun has an enormous effect on ionospheric radiowave propagation and radio communications in general. The energy the Sun generates creates the ionisation that enables radio communications signals to be refracted by the ionosphere. As a result an understanding of its structure and nature helps provide a wider understanding of ionospheric propagation.
How the sun affects radio signal propagation
Solar disturbances
Sunspots

Ionospheric propagation - predictions, disturbances, etc

Ionospheric propagation is subject to many changes. Understanding the effects that may arise and predicting conditions is of great importnace to those using ionospheric propagation.
Sudden ionospheric disturbance, SID
Radio propagation prediction using solar indices
Radio propagation prediction software

Radiowave propagation in the troposphere

For frequencies at VHF and above different modes of propagation prevail. Although some ionospheric modes may be experienced, the main effects are caused by changes in the troposphere.
Tropospheric propagation
Troposcatter

Special forms of radiowave propagation

There is a variety of specialised forms of radio signal propagation that can be used to good effect for specialised applications. These include such forms of propagation as meteor scatter, troposcatter, "Moon bounce" and others.
Meteor scatter or meteor burst communications