HF Communications

Courses on RF Systems
  • Course:HF Communications
  • Course ID:HF Duration:1-2 days Where: Your Office (7+ Persons)
  • Available as a private, customized course for your group at your offices or ours and in some cases as a WebLive(TM) class.

  • Download Course Description (PDF)

Course Outline

  • Introduction
    • History of HF communications
    • Terrestrial wireless communications challenges:  Attenuation, reflection, diffraction, scattering, multipath effects, interference
  • Spectrum Basics
    • Electromagnetic spectrum:  Bands and uses, regulation
    • More about the HF band
    • Spectrum issues:  Line of Sight (LOS) transmission, path loss, etc
  • Radio Propagation
    • Electromagnetic field
    • Ground and surface waves:  What, when
    • Direct waves:  Direct LOS, Fresnel theory, free space loss, sum operating margin
    • Sky waves (Ionosphere)
      • Key concepts
      • Structure of the Ionosphere:  D, E, F1, F2
      • Critical frequencies:  MUF, LUF
      • Propagation effects:  Daily, seasonal, geographic, sunspots, interference, weather, solar flares
      • Propagation indices:  K, Ap, Solar flux, Sunspot number
    • Tropospheric waves
  • Antennas
    • Characteristics:  Dimensions, gain (dB), polarization, F/B ratio, VSWR, radiation diagrams, HPB
    • Types:  Directional, omnidirectional
      • Whip, dipole, inverted Vee, Loop, beams
      • Practical examples
  • Modulation and Communication Modes
    • Modulation
      • Analog:  AM, SSB, FM, PM
      • Digital:  xFSK, xASK, xPSK, xQAM
    • Modes
      • CW-Morse
      • AM voice/SSB voice
      • FM voice
      • Digital:  Modems/examples
  • HF Radios
    • Types:  Analog, digital, portable, vehicle, nomadic, fixed
    • Types:  analog, digital, portable, vehicle-mounted, nomadic, fixed
    • Architecture
    • Characteristics
      • Power
      • Channels
      • Modulation
  • Uses of HF Communications
    • Long distance/amateur radio
    • Emergency (including disasters) communications
    • Maritime uses
    • Military applications
    • Examples
  • Link Budget Calculations
    • Basic principles
    • Tools
    • Calculation exercise
  • Emerging Trends
    • Automatic link establishment
    • Digital new services
  • Conclusion
    • Comparison of satellite and HF communications
    • Advantages and disadvantages
    • Course recap, Q/A, and Evaluations



Course Overview

Course in a Nutshell

For decades, HF communications have been an important, in some cases the only, way of providing long distance communication. HF makes it possible to reach people wherever they may be located, whether in the jungles of Congo, bushes of Australia, or the sands of Sahara.

In this course you will learn both the technology and applications of HF communication, both speech and digital uses such as modem utility, browsing, and mailing, to cite a few examples. For anyone involved with long-distance connectivity, understanding HF technology is a must.

We will start the course by learning the essential RF propagation concepts. We will then review the challenges offered by HF communications and how we can go about addressing them. We will place particular emphasis on the antenna technology that makes worldwide connectivity possible. We will go on to learn about modulations schemes and communications modes, architecture and design of an HF radio system, and the applications of HF. We will conclude with a comparison of HF with competing technologies and a look at the future of HF. All in all, the course will provide you with a thorough and practical introduction to HF communications.


Customize It!

We can customize this course to the background and needs of your specific audience. For example, we can extend the course to include the prerequisite material or tailor the course topics to include the applications or issues of particular interest to you.


Learn How To

  • List the key components of an HF system and describe how they fit together
  • Explain how radio waves operate in different environments
  • Design an HF communications system
  • Describe the current markets and applications for HF communications


Audience / Prerequisites

Aimed At

Those involved in the military or commercial uses of HF communications who wish to learn more about this technology.



Some prior familiarity with the basics of radio will be helpful.