Radiowave propagation-the basis of radiocommunication

Radiowave propagation, progressively studied and understood during the past 100 years, has been exploited to provide an ever-growing range of radiocommunication services. The laboratory demonstrations of the existence of electromagnetic waves with radio wavelengths by Hertz in 1887-8 built upon the research into electromagnetism in the first half of the nineteenth century by Faraday and others, and upon the theoretical work of Maxwell in the 1860s and 70s. Hertz demonstrated reflection and refraction and measured the wavelength and velocity of the radiation. Theory and experiment suggested that radio communication was limited to a range of 200-300 km until Marconi tried to communicate across the Atlantic. Marconi's success led to a proposed revision of diffraction theory in order to account for the result; fortunately this was quickly refuted by Lord Rayleigh. It also led to the suggestion, independently by Heaviside and Kennelly, of an ionised reflecting layer in the upper atmosphere. A survey of low and medium frequency propagation, HF ionospheric propagation, and propagation at frequencies above 30 MHz is included.