The need for propagation studies

Although radio-wave propagation has been studied over a considerable period of time, there is a continuing and expanding need for new studies. The requirements for communication, and particularly for the transmission of data signals, necessitate studies in more detail than previously, if reliable statistics for the determination of system performance are to be established. New technologies open up the possibility for economic communication at higher frequencies, and new applications. Each application seeks to stretch the propagation performance to its limits. This paper outlines four key areas where new propagation data are urgently required. The mobile services are expanding extremely fast with the aim of providing personal communications to individuals on the move. Increased use of the radio spectrum for both terrestrial and space communications involves considerable frequency sharing with the need to plan and co-ordinate services effectively. Because of the nature of radio-wave propagation such co-ordination is international, and prediction methods are required for use by future World Administrative Radio Conferences. Developments in radio technology now allow communications at millimetric wavelengths to be considered, and detailed propagation information is still required. At the other end of the spectrum propagation via the ionosphere continues to offer a cheap and flexible means of communicating over long distances, but additional information is required to facilitate the design of automatic systems and digital modulation methods.