Critical analysis for design of HF radio link in Brazil

Radio frequency (RF) transmission between 3 and 30 MHz by ITU convention is called high frequency (HF) or shortwave radio. HF is widely used communication band for long distances. The use of HF radio transmission has been experiencing a renewal of interest and investment in Europe and USA, because of the realization that satellite and terrestrial communication modes are vulnerable to electronic countermeasures and physical destruction HF radio transmission, although of much lower overall reliability and limited data bandwidth than other communication bands, allow communication over long distances the level of recovery furnished by HF is much more improved than the case of satellite and terrestrial communication modes. In Brazil meanwhile this frequency mode is quite unusual and the official documentation provided by the Brazilian official agency called ANATEL for the radio link conception is not complete and it has many mistakes. This paper propose to make an overall about the topics that are important in the radio-link conception and also propose some differential steps in the HF prediction, some useful aspects of system design not afforded in the rules of the Brazilian agency and a critical analysis of the possible used HF antennas.