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Knowing the terminology used in HF radio propagation can help you understand long-distance communication via skywaves.
Find below a glossary of basic terms and an extended index of terms related to HF radio propagation:
A glossary of basic terms
- Frequency (f) is the number of cycles of a radio wave that occur in one second, measured in hertz (Hz).
- Wavelength (λ) is the distance between two consecutive points in a wave, usually measured in meters (m).
The relationship between wavelength and frequency is inverse, with higher frequencies corresponding to shorter wavelengths and vice versa.
- Groundwave propagation is the use of radio waves that travel along the earth's surface, providing communication over relatively short distances, typically up to a few hundred kilometers.
- Skywave propagation is the phenomenon in which HF radio waves are bounced back to earth's surface, allowing long-distance communication beyond the line of sight.
- The ionosphere is the region of the earth's upper atmosphere (approximately 50 to 600 kilometers above the ground) where ionization occurs due to solar radiation. This region plays a crucial role in HF radio propagation by reflecting and refracting radio waves.
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Skip Distance is the minimum distance from the transmitter for receiving skywaves, while Blind, or Dead Zone, refers to the region with poor or nonexistent reception.
- MUF (Maximum Usable frequency) is the highest frequency at which skywave propagation is reliably achievable between two points on earth during a specific time and under specific ionospheric conditions.
- LUF (Lowest Usable frequency) is the lowest frequency at which skywave propagation can be used effectively.
- Fading (QSB) is the variation in signal strength and quality experienced during radio transmission due to changes in ionospheric conditions, interference, or other factors.
- The F-layer is the upper region of the ionosphere that consists of two sub-layers, f1 and f2, and is the primary region for HF propagation. The f2 is particularly important for long-distance communication.
- The E-layer is the middle region located below the F-region. This layer is responsible for sporadic e-skip propagation, which can enable HF communication at higher frequencies.
- The D-layer is the lowest region of the ionosphere, located at an altitude of approximately 48 to 90 kilometers. The D-layer absorbs HF radio waves during daylight hours, affecting propagation.
- The critical frequency (fc) is the highest frequency that can be transmitted vertically and still return to earth via skywave propagation.
- The Optimum Working frequency (OWF) is the frequency that provides the best propagation conditions for a given HF communication path.
- The Solar flux Index (SFI) is a measure of the sun's radio emissions at a specific wavelength (usually 10.7 cm). It is used as an indicator of solar activity, which affects ionospheric conditions and HF propagation.
- The A-index is a daily measure of geomagnetic activity on a scale from 0 to 400, with lower values indicating quieter geomagnetic conditions. Geomagnetic activity can disrupt HF propagation.
Extended index of terms
A list of terms that are explained on this website:
- A-Index
- Absorption
- ACE - Advanced composition explorer
- ALE — Automatic link establishment
- Amateur radio
- Amateur radio bands
- Amateur radio propagation today
- Angle elevation/transmission
- Applications for analyzing and forecasting HF propagation
- Applications used for forecasts and predictions (references)
- Aurora
- At what Kp index can I see aurora?
- Band conditions
- Band conditions banners
- Beacons
- Blackouts; R1-5 scale
- Blind zone
- Bt - total strength of the Interplanetary Magnetic field (IMF)
- Bz - orientation of the IMF
- Carrington event
- ChatGPT learns about forecasting tools for radio amateurs
- Chirping
- Clouds of plasma in the ionosphere
- CME - coronal Mass ejection
- Compare DR2W propagation tool with VOACAP
- Compare forecasting tools for HF radio propagation
- Compare forecasting tools for radio amateurs
- Communication conditions
- Complex HF propagation Modes
- Conductive ground
- Coronal Mass ejection (CME)
- Current band conditions
- Current Ham radio conditions
- Current HF band conditions maps for radio operators
- Current HF band conditions online map
- Current HF propagation
- Current HF propagation conditions
- Current HF propagation conditions fAQ
- Current HF radio propagation
- Current propagation conditions
- Current shortwave propagation conditions
- Current solar activity
- Current solar events
- Critical frequency Map
- D-layer
- Dead Zone
- Digisonde Directogram
- Direct wave propagation
- DX clusters DX Spots
- DX propagation map
- DX propagation online map
- DX propagation prediction
- DXMAPS
- DXWatch
- DXZone
- E-layer
- Earth's magnetic field
- Earth's Magnetosphere
- Earth Magnetosphere vs Earth's magnetic field
- Earth observing system (EOS)
- Earth's magnetic field
- Effects of solar activity on amateur radio
- Electron densities
- Electron flux (Ef)
- Electromagnetic Radiation
- Electromagnetic Spectrum
- EME Deg - earth-Moon-Earth Degradation
- EsEU - Sporadic e europe
- EsNA - Sporadic e North America
- EUV sunlight
- FAQ about HF propagation
- F10.7
- F-layer
- Flare (Solar physics)
- foF2 - critical frequency
- foF2 map
- Forecast HF propagation conditions
- Forecast HF radio propagation - applications
- Forecast propagation for radio amateurs
- Forecast vs prediction of HF band conditions
- Forecasting HF propagation for radio amateurs
- Forecasting MUF for a 3000 Km path
- Forecasting tools for radio amateurs
- G1-G5 - scale of Geomagnetic storms
- Gamma rays
- Gama rays bursts (GRB)
- GRB - Gama-rays bursts
- "GeoMag" (index) - earth`s geomagnetic field activity
- Geomagnetic
- Geomagnetic conditions
- Geomagnetic data
- Geomagnetic field activity
- Geomagnetic indices K, A
- Geomagnetic storms; G1-5 scale
- Geophysical activity
- Global conditions
- Global HF propagation
- Global radio propagation conditions
- Greyline
- Greyline radio propagation explained
- Greyline vs "Solar Terminator"
- Ground wave
- Ground wave propagation
- Ground waves
- Groundwave
- Hale cycle
- Ham bands' activity
- Ham propagation map
- Ham radio HF propagation (real-time)
- Ham radio propagation conditions
- Ham radio propagation tutorial
- Ham solar
- Helium lines
- HF bands allocated for radio amateurs
- HF bands allocated for radio amateurs and their characteristics
- HF band conditions
- HF band conditions maps
- HF bands Info affected by solar conditions
- HF bands Monitoring
- HF conditions
- HF propagation
- HF propagation app
- HF propagation blackout
- HF propagation calculator
- HF propagation chart
- HF propagation conditions
- HF propagation conditions at a glance
- HF propagation experts
- HF propagation explained
- HF propagation explanation
- HF propagation fadeouts
- HF propagation for radio amateurs
- HF propagation for radio hams
- HF propagation forecast for radio amateurs
- HF propagation forecast tools
- HF propagation forecast tools
- HF Propagation Forecasting
- HF propagation: fundamentals
- HF propagation live map
- HF propagation map
- HF propagation model
- HF propagation modes
- HF propagation online map
- HF propagation overview
- HF propagation now (real-time)
- HF propagation predictions
- HF propagation prediction online
- HF propagation prediction software
- HF propagation preface
- HF propagation reporter
- HF propagation Status
- HF propagation — The basics
- HF propagation today
- HF propagation Tools
- HF radio propagation prediction
- HF radio propagation tutorial for radio amateurs
- HF propagation widget
- HF radio conditions
- HF radio propagation
- HF signals propagation
- HF radio propagation forecast
- HF radio propagation today
- HF radio waves (basics)
- HF radio wave propagation factors
- HF radio propagation prediction
- HF Skywave propagation for radio amateurs
- HF wave propagation
- HFTA - High frequency Terrain Assessment
- Helium lines
- High frequency
- IMF - Interplanetary Magnetic field
- Impacts of space weather
- Incident angle
- Interplanetary Magnetic field (IMF)
- Introduction to HF propagation
- Ionisation
- Ionization
- Ionogram
- Ionosonde
- Ionosphere
- Ionosphere and HF radio propagation
- Ionosphere layers
- Ionosphere propagation of radio waves
- Ionosphere, radio waves
- Ionosphere probing
- Ionosphere regions
- Ionospheric absorption
- Ionospheric bubbles
- Ionospheric clouds
- Ionospheric conditions
- Ionospheric data
- Ionospheric disturbances
- Ionospheric irregularities
- Ionospheric layers
- Ionospheric layers summary
- Ionospheric propagation
- Ionospheric reflection
- Ionospheric refraction
- Ionospheric skywave propagation
- Ionospheric storm
- ITU model
- K Index
- Kp index
- KiwiSDR map of remote public SDR receivers accessible via the Internet
- Lagrange points
- Layers of ionization
- Learning about space weather
- Line-Of-Sight propagation (LOS)
- Live HF propagation map
- Long-distance communication
- Live solar events and past solar activity
- LOS
- LOS - Line of sight propagation
- LUF - Lowest Usable frequency
- Magnetic field
- Magnetosphere (MS)
- Maximum usable frequency (MUF)
- Maximum usable frequency map
- Modes of HF radio propagation
- Modes of radio propagation
- Monitor band activity of radio amateurs
- Monitring HF propagation
- MS — Meteor Scatter Activity
- MUF — Maximum Usable frequency
- MUF Indicators
- MUF How what, why?
- MUF factor
- MUF map
- MUF propagation map by KC2G for a 3,000 Km hop
- MUF propagation online map
- Near real-time regional maps
- NOAA
- Noise level
- NVIS
- NVIS map
- NVIS propagation
- NVIS tutorial
- Observations - Geo (Terrestrial) & Solar
- On-Line HF propagation prediction
- Online propagation tools
- Optimal Sending frequency
- OWF - Optimum Working frequency
- Past solar activity
- Plasma
- Plasma clouds
- Polar cap absorption (PCA)
- Practical applications
- Predict conditions
- Predict HF radio propagation
- Predict MUF
- Predict propagation
- Predict skywave propagation now
- Predict sunspot numbers
- Prediction of sky-wave propagation conditions
- Predicting propagation
- Prediction vs forecast of HF band conditions
- Propagation conditions
- Propagation DX
- Propagation forecast
- Propagation indices single: propagation index
- Propagation modes
- Propagation of high frequency radio waves
- Propagation of HF radio waves -
Global conditions and Regional conditions
- Propagation of shortwave radio
- Proton flux
- Propagation | modes of HF radio propagation
- Propagation forecast
- propagation of high frequency radio waves | the rebirth of hf
- Propagation of radio waves explained
- Propagation prediction
- Propagation prediction programs and forecasts
- Proton flux (Pf)
- PSKR - PSK reporter
- Quick guide to HF propagation using solar indices
- Radio Amateur
- Radio amateurs HF bands charactaristics
- Radio blackouts / fadeouts; R1-5 scale
- Radio frequency
- Radio propagation
- Radio propagation beacon
- Radio propagation forecast
- Radio propagation free software
- Radio propagation online tools
- Radio propagation software
- Radio propagation tool
- Radio propagation tutorial
- Radio wave propagation in the ionosphere
- Radio waves
- Radio waves propagation
- Radio wave propagation model
- Radio-wave HF propagation models
- Radio-wave propagation modes
- Ray tracing (Optics)
- RBN - Reverse beacon Network
- Real-time activity of radio amateurs
- Real-time band conditions
- Real-time DX data
- Real-time DX propagation conditions
- Real-time HF band conditions
- Real-Time hf propagation charts
- Real-time HF propagation prediction
- Ham radio HF propagation real-time
- Real-time HF propagation reports
- Real-time MUF 3000 Km propagation map
- Real-Time MUF and solar indices
- Real-time MUF map
- Real-time propagation and band conditions
- Real-time radio propagation reports
- Real-time reports of HF propagation
- Real-time reports of radio propagation
- Real-time reports of space weather
- Real-time space weather reports
- Real-time watching of worldwide hams' activity
- Recent geophysical & solar observations
- Recent MUF distribution
- Recent observations - Geo (Terrestrial) & Solar
- Recent sunspot number
- Regional conditions
- Regional HF conditions
- Regional MUF and solar indices
- Regional vs Global HF propgation conditions
- Regional vs Global propgation conditions
- Regions of ionization
- Remote sensing of the ionosphere
- Reports of space weather
- RSG scales of Space Weather
- SDO - Solar Dynamic Obervatory (NASA)
- SDR - Software Defined radio
- SDR spectrum
- Seasonal variations in HF radio propagation
- Seasons affect HF radio propagation
- SEP
- SFI - Solar flux Index
- Shortwave propagation
- Shortwave propagation conditions
- Shortwave propagation forecast
- Shortwave radio propagation
- SID - Sudden ionospheric disturbances
- Significant frequencies relevant to skywaves
- Skip distance
- Skip zone
- Skywave
- Skywave HF radio propagation
- Skywave propagation
- Skywave propagation conditions
- Skywave propagation for radio amateurs
- Skywave propagation forecast
- Skywave propagation tutorial
- Software for HF propagation prediction
- Solar activity
- Solar Activity & Ham radio propagation
- Solar activity affects HF propagation
- Solar activity affects skywaves
- Solar activity for radio amateurs
- Solar conditions affect HF radio propagation
- Solar conditions and HF radio propagation
- Solar cycle
- Solar data
- Solar events
- Solar energetic Particle (SEP)
- Solar events
- Solar flares
- Solar flux index (SFI)
- Solar Ham
- Solar indices
- Solar observations
- Solar maximum
- Solar minimum
- Solar Particle event (SPE)
- Solar phenomena
- Solar radiation
- Solar radiation storms (flares); S1-5 scale
- Solar radio flux
- Solar spectra
- Solar storms
- Solar synoptic map
- Solar terminator (i.e. Greyline)
- Solar wind; The impact of the solar wind on HF radio transmission.
- Solar wind reports
- Solar X-Ray (Phenomenon)
- Solar X-ray Imaging system (SXI)
- Solar X-Ray flux levels
- Space wave
- Space weather
- Space weather data and plots
- Space weather events
- Space weather forecasts
- Space weather prediction
- Space weather prediction center (NOAA)
- Space Weather predictions for radio amateurs
- Space weather reports
- Space weather scales
- SPE
- Sudden ionospheric disturbances
- Sunspots
- SuperDARN
- SWPC = Space Weather prediction center (NOAA)
- Sporadic e
- Stratosphere
- Sudden ionospheric disturbances (SID)
- Sunlight
- Sunspots
- Sunspot cycle
- Sunspot number (SSN)
- Sunspots recent days
- Sunspots today
- Surface wave propagation
- Space Weather prediction center (NOAA)
- T Index map
- TEC - Total electron content
- Terminator line
- Terrestrial geomagnetic indices
- Terrestrial observations
- The Rebirth of Shortwave radio communication
- The Super Dual Auroral Radar Network (SuperDARN)
- Thermosphere
- TID (Traveling ionospheric disturbances)
- Tools for analyzing and forecasting HF propagation
- Total electron content — TEC
- Traveling ionospheric disturbances (TID)
- Troposphere
- Twilight zone
- Ultraviolet
- Understanding Ham bands conditions banner
- Understanding Ham radio propagation
- Understanding HF propagation
- Understanding HF Propagation
- Understanding HF propagation Numbers
- Understanding HF radio propagation
- Understanding NVIS
- Understanding Skywave propagation
- Usable HF frequencies
- Using HF beacon tracking programs
- Variations in HF radio propagation
- Very High frequency (VHF)
- Very Low frequency (VLF)
- VHF propagation map
- View HF bands conditions at a glance
- Visualizing HF propagation
- VOACAP
- Wave propagation
- Wide-band WebSDR
- World-wide Space Weather agencies & services
- WSPR - Weak Signal propagation reporter * WSPR Live * WSPR Rocks * WSPRnet
- X-Ray flares
- X-Ray flux levels (scale)
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Terms related to HF radio propagation