↑ Terminology related to HF radio propagation

This page is part of the project "Understanding HF Propagation."
by Doron Tal, 4X4XM
 

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

    Waves and radio propagation

  1. Frequency (f) is the number of cycles of a radio wave that occur in one second, measured in hertz (Hz).
  2. 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.
  3. 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.
  4. Skywave propagation is the phenomenon in which HF radio waves are bounced back to earth's surface, via the ionosphere, allowing long-distance communication beyond the line of sight.
  5. The ionosphere is the region of the earth's upper atmosphere (approximately 50 to 800 kilometers above the ground) where ionization occurs due to solar radiation. This region plays a crucial role in HF radio propagation by bouncing radio waves back to Earth. The ionosphere is continuously changing due to natural storms, as explained below: A storm represents a disturbed state of the natural environment, characterized by significant disruptions to normal conditions. In this project, we specifically refer to:
    1. Solar storms occur on the sun.
    2. Space weather storms occur in the space between the sun and Earth.
    3. Geomagnetic storms (also known as magnetic storms) are temporary disturbances of the Earth's magnetosphere caused by a solar wind shock wave.
    4. Ionospheric storms involve varying densities of energized free electrons in the ionosphere due to geomagnetic storms.
    5. Understanding the dynamics of solar and space weather storms reveals the intricate relationship between our sun and Earth. Solar storms, originating on the sun, unleash powerful energy that travels through space, affecting not only the celestial environment but also our planet's magnetic field. When these solar winds encounter Earth's atmosphere, they can trigger geomagnetic storms, which are temporary disturbances that disrupt communication systems and power grids. Additionally, the presence of energized free electrons in the ionosphere gives rise to ionospheric storms, further complicating our technological landscape.
  6. 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.
  7. 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.
  8. LUF (Lowest Usable Frequency) is the lowest frequency at which skywave propagation can be used effectively.
  9. Fading (QSB) is the variation in signal strength and quality experienced during radio transmission due to changes in ionospheric conditions, interference, or other factors.
  10. The F-region is the upper region of the ionosphere that consists of two sub-regions, F1 and F2, and is the primary region for HF propagation. The F2 is particularly important for long-distance communication.
  11. The E-region is the middle region located below the F-region. It is responsible for sporadic E propagation, which can enable HF communication at higher frequencies.
  12. The D-region is the lowest region of the ionosphere, located at an altitude of approximately 48 to 90 kilometers. The D-region absorbs HF radio waves during daylight hours, affecting propagation.
  13. The ionosphere bounces a radio wave at vertical incidence below the critical frequency (fc), regardless of transmitter power.
  14. The Optimum Working Frequency (OWF) is the frequency that provides the best propagation conditions for a given HF communication path.
  15. 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.
  16. 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.
  17. The K-index represents short-term (3-hour) geomagnetic activity at a specific geomagnetic station. It quantifies disturbances in Earth’s horizontal magnetic field by comparing geomagnetic fluctuations, measured by a magnetometer, to a quiet day. The K-scale is logarithmic, a scale from 0 to 9.

Extended index of terms

A list of terms that are explained on this website:


    A
  1. A guide for radio hams
  2. A review of the propagation indices — A review of skywave propagation indicators
  3. A-Index
  4. Absorption of skywaves
  5. ACE - Advanced composition explorer
  6. ALE — Automatic link establishment
  7. Amateur radio
  8. Amateur radio bands
  9. Amateur radio propagation today
  10. Angle elevation/transmission
  11. Applications for analyzing and forecasting HF propagation
  12. Applications used for forecasts and predictions (references)
  13. Aurora
  14. At what Kp index can I see aurora?

    B
  15. Band conditions
  16. Band conditions banners
  17. Band Opennings
  18. Beacons
  19. Benefits of the HAARP Project for Radio Hams
  20. Beyond line of site (BLOS)
  21. Blackouts; R1-5 scale
  22. Blind zone
  23. BLOS (Beyond line of site)
  24. Bt - total strength of the Interplanetary Magnetic field (IMF)
  25. Bz - orientation of the IMF

    C
  26. Carrington event
  27. ChatGPT learns about forecasting tools for radio amateurs
  28. Chirping
  29. Clouds of plasma in the ionosphere
  30. CME - coronal Mass ejection
  31. Compare DR2W propagation tool with VOACAP
  32. Compare forecasting tools for HF radio propagation
  33. Compare forecasting tools for radio amateurs
  34. Communication conditions
  35. Complex HF propagation Modes
  36. Conductive ground
  37. Coronal Mass ejection (CME)
  38. Current band conditions
  39. Current Ham radio conditions
  40. Current HF band conditions maps for radio operators
  41. Current HF band conditions online map
  42. Current HF propagation
  43. Current HF propagation conditions
  44. Current HF radio propagation
  45. Current propagation conditions
  46. Current shortwave propagation conditions
  47. Current solar activity
  48. Current solar events
  49. Critical frequency
  50. Critical frequencies concept
  51. Critical frequency map
  52. D-region
  53. Dead zone
  54. Digisonde directogram
  55. Direct wave propagation (LOS - Line Of Site)
  56. DX clusters DX Spots

    D
  57. DX propagation map
  58. DX propagation online map
  59. DX propagation prediction
  60. DXMAPS
  61. DXWatch
  62. DXZone

    E
  63. E-region
  64. Earth's magnetic field
  65. Earth's Magnetosphere
  66. Earth Magnetosphere vs Earth's magnetic field
  67. Earth observing system (EOS)
  68. Earth's magnetic field
  69. Effects of solar activity on amateur radio
  70. Electron densities
  71. Electron flux (Ef)
  72. Electromagnetic Radiation
  73. Electromagnetic Spectrum
  74. Electromagnetic Wave
  75. Electromagnetic Spectrum
  76. Electromagnetic Radiation
  77. Electromagnetic Wave
  78. Elevation Angle
  79. EME Deg - earth-Moon-Earth Degradation
  80. EsEU - Sporadic e europe
  81. EsNA - Sporadic e North America
  82. EUV sunlight

    F
  83. FAQ about HF propagation
  84. FAQ: Current HF propagation conditions
  85. F10.7
  86. F-region
  87. Flare
  88. foF2 - critical frequency
  89. foF2 map
  90. Forecast HF propagation conditions
  91. Forecast HF radio propagation - applications
  92. Forecast propagation
  93. Forecast propagation for radio amateurs
  94. Forecast vs prediction of HF band conditions
  95. Forecasting HF propagation for radio amateurs
  96. Forecasting MUF for a 3000 km path
  97. Forecasting tools for radio amateurs
  98. Free Electron Density

    G
  99. G1-G5 - scale of Geomagnetic storms
  100. Gamma rays
  101. Gama rays bursts (GRB)
  102. GRB - Gama-rays bursts
  103. "GeoMag" (index) - earth`s geomagnetic field activity
  104. Geomagnetic
  105. Geomagnetic activity | What is Geomagnetic activity
  106. Geomagnetic conditions
  107. Geomagnetic data
  108. Geomagnetic field activity
  109. Geomagnetic indices K, A
  110. Geomagnetic storms and HF communications
  111. Geomagnetic storms; G1-5 scale
  112. Global conditions
  113. Global HF propagation
  114. Global radio propagation conditions
  115. Greyline
  116. Greyline radio propagation explained
  117. Greyline vs "Solar Terminator"
  118. Ground wave
  119. Ground wave propagation
  120. Ground waves

    H
  121. Hale cycle
  122. Ham bands' activity
  123. Ham propagation map
  124. Ham radio HF propagation (real-time)
  125. Ham radio propagation conditions
  126. Ham radio propagation tutorial
  127. Ham Radio Range Guide: How Far Can You Talk?
  128. Ham solar
  129. Helium lines
  130. HF bands allocated for radio amateurs
  131. HF bands allocated for radio amateurs and their characteristics
  132. HF band conditions
  133. HF band conditions maps
  134. HF bands Info affected by solar conditions
  135. HF bands Monitoring
  136. HF conditions
  137. HF propagation
  138. HF propagation app
  139. HF propagation blackout
  140. HF propagation calculator
  141. HF propagation chart
  142. HF propagation conditions
  143. HF propagation conditions at a glance
  144. HF propagation experts
  145. HF propagation explained
  146. HF propagation explanation
  147. HF propagation fadeouts
  148. HF propagation for beginners and advanced
  149. HF propagation for radio amateurs
  150. HF propagation for radio hams
  151. HF propagation forecast for radio amateurs
  152. HF propagation forecast tools
  153. HF Propagation Forecasting
  154. HF propagation: fundamentals
  155. HF propagation live map
  156. HF propagation map
  157. HF propagation models
  158. HF propagation modes
  159. HF propagation online map
  160. HF propagation overview
  161. HF propagation now (real-time)
  162. HF propagation predictions
  163. HF propagation prediction online
  164. HF propagation prediction software
  165. HF propagation preface
  166. HF propagation reporter
  167. HF propagation Status
  168. HF propagation — The basics
  169. HF Propagation Today
  170. HF Propagation Tools
  171. HF radio propagation indices and scales
  172. HF radio propagation prediction
  173. HF radio propagation tutorial for radio amateurs
  174. HF propagation widget
  175. HF radio conditions
  176. HF radio propagation
  177. HF signals propagation
  178. HF skywave window: LUF—MUF
  179. HF radio propagation forecast
  180. HF radio propagation today
  181. HF radio wave propagation
  182. HF radio waves (basics)
  183. HF radio wave propagation factors
  184. HF radio propagation prediction
  185. HF Skywave propagation for radio amateurs
  186. HF wave propagation
  187. HFTA - High frequency Terrain Assessment
  188. Helium lines
  189. High frequency
  190. Highest Possible Frequency (HPF)
  191. HPF—Highest Possible Frequency


  192. I
  193. IMF - Interplanetary Magnetic field
  194. Impacts of space weather
  195. Incident angle
  196. Interplanetary Magnetic field (IMF)
  197. Introduction to HF propagation
  198. Ionisation
  199. Ionization
  200. Ionogram
  201. Ionosonde
  202. Ionosphere
  203. Ionosphere and HF radio propagation
  204. Ionosphere propagation of radio waves
  205. Ionosphere regions
  206. Ionosphere, radio waves
  207. Ionosphere probing
  208. Ionosphere regions
  209. Ionospheric absorption in particular within D-region
  210. Ionospheric bubbles
  211. Ionospheric clouds
  212. Ionospheric conditions
  213. Ionospheric data
  214. Ionospheric disturbances
  215. Ionospheric irregularities
  216. Ionospheric propagation
  217. Ionospheric refraction
  218. Ionospheric regions
  219. Ionospheric skywave propagation
  220. Ionospheric storms
  221. IRI ionospheric model
  222. ITU model

    K
  223. K-Index
  224. Key concepts of HF propagation
  225. Key Factors Affecting HF Propagation
  226. Kp index
  227. KiwiSDR map of remote public SDR receivers accessible via the Internet

    L
  228. Lagrange points
  229. Learning about space weather
  230. Line-Of-Sight propagation (LOS)
  231. Live HF propagation map
  232. Long-distance communication
  233. Live solar events and past solar activity
  234. LOS
  235. LOS - Line of sight propagation
  236. LUF - Lowest Usable frequency
  237. LUF Chart - The Lowest Usable frequency map

    M
  238. Magnetic field
  239. Magnetosphere (MS)
  240. Maximum usable frequency (MUF)
  241. Maximum usable frequency map
  242. Minimum usable frequency map
  243. Modes of HF radio propagation
  244. Modes of radio propagation
  245. Monitor band activity of radio amateurs🗗
  246. Monitring HF propagation
  247. MS — Meteor Scatter Activity
  248. MUF — Maximum Usable frequency
  249. MUF Indicators
  250. MUF How what, why?
  251. MUF factor
  252. MUF map
  253. MUF propagation map by KC2G for a 3,000 km hop
  254. MUF propagation online map

    N
  255. Near real-time regional maps
  256. NET ionospheric model
  257. NOAA National Oceanic and Atmospheric Administration
  258. Noise level
  259. NVIS
  260. NVIS map
  261. NVIS propagation
  262. NVIS propagation concept
  263. NVIS tutorial

    O
  264. Observations - Terrestrial & Solar
  265. On-Line HF propagation prediction
  266. Online propagation tools
  267. Online real-time propagation charts
  268. Optimal Sending frequency
  269. OWF - Optimum Working frequency

    P
  270. Past solar activity
  271. PCA—polar cap absorption
  272. Plasma
  273. Plasma clouds
  274. Polar cap absorption (PCA)
  275. Practical applications
  276. Predict conditions
  277. Predict HF radio propagation
  278. Predict MUF
  279. Predict propagation
  280. Predict skywave propagation now
  281. Predict sunspot numbers
  282. Prediction of sky-wave propagation conditions
  283. Predicting propagation
  284. Prediction vs forecast of HF band conditions
  285. Propagation conditions
  286. Propagation DX
  287. Propagation factors and conditions
  288. Propagation forecast
  289. Propagation indices single: propagation index
  290. Propagation modes
  291. Propagation of high frequency radio waves
  292. Propagation of HF radio waves - Global conditions and Regional conditions
  293. Propagation of shortwave radio
  294. Proton flux
  295. Propagation | modes of HF radio propagation
  296. Propagation forecast
  297. propagation of high frequency radio waves | the rebirth of hf
  298. Propagation of radio waves explained
  299. Propagation prediction
  300. Propagation prediction programs and forecasts
  301. Proton flux (Pf)
  302. PSKR - PSK reporter

    Q
  303. Quick guide to HF propagation using solar indices

    R
  304. Radio Amateur
  305. Radio amateurs HF bands charactaristics
  306. Radio blackouts / fadeouts; R1-5 scale
  307. Radio frequency
  308. Radio propagation
  309. Radio propagation beacon
  310. Radio propagation forecast
  311. Radio propagation free software
  312. Radio propagation online tools
  313. Radio propagation properties
  314. Radio propagation software
  315. Radio propagation tool
  316. Radio propagation tutorial
  317. Radio wave propagation in the ionosphere
  318. Radio spectrum
  319. Radio waves
  320. Radio waves propagation
  321. Radio wave propagation model
  322. Radio-wave HF propagation models
  323. Radio-wave propagation modes
  324. Ray tracing (Optics)
  325. RBN - Reverse beacon Network
  326. Real-time activity of radio amateurs
  327. Real-time band conditions
  328. Real-time DX data
  329. Real-time DX propagation conditions
  330. Real-time HF band conditions
  331. Real-Time hf propagation charts
  332. Real-time HF propagation prediction
  333. Ham radio HF propagation real-time
  334. Real-time HF propagation reports
  335. Real-time ham band activity using the internet
  336. Real-time MUF 3000 km propagation map
  337. Real-Time MUF and solar indices
  338. Real-time MUF map
  339. Real-time propagation and band conditions
  340. Real-time radio propagation reports
  341. Real-time reports of HF propagation
  342. Real-time reports of radio propagation
  343. Real-time reports of space weather
  344. Real-time space weather reports
  345. Real-time watching of worldwide hams' activity
  346. Real-time watching of worldwide ham activity
  347. Recent geophysical & solar observations
  348. Recent MUF distribution
  349. Recent observations - Geo (Terrestrial) & Solar
  350. Recent sunspot number
  351. Regional conditions
  352. Regional HF conditions
  353. Regional MUF and solar indices
  354. Regional vs Global HF propgation conditions
  355. Regional vs Global propgation conditions
  356. Regions of ionization
  357. Region vs. Layer: Earth's Atmosphere and Ionosphere
  358. Remote sensing of the ionosphere
  359. Reports of space weather
  360. RSG scales of Space Weather

    S
  361. Satellites for space weather observations
  362. SDO - Solar Dynamic Obervatory (NASA)
  363. SDR - Software Defined radio
  364. SDR spectrum
  365. Seasonal variations in HF radio propagation
  366. Seasons affect HF radio propagation
  367. SEP
  368. SFI - Solar flux Index
  369. Shortwave propagation
  370. Shortwave propagation conditions
  371. Shortwave propagation forecast
  372. Shortwave radio propagation
  373. SID - Sudden ionospheric disturbances
  374. Significant frequencies relevant to skywaves
  375. Skip distance
  376. Skip zone
  377. Skywave
  378. Skywave HF radio propagation
  379. Skywave propagation
  380. Skywave propagation concept
  381. Skywave propagation conditions
  382. Skywave propagation for radio amateurs
  383. Skywave propagation forecast
  384. Skywave propagation tutorial
  385. Software for HF propagation prediction
  386. Solar activity
  387. Solar Activity & Ham radio propagation
  388. Solar activity affects HF propagation
  389. Solar activity affects skywaves
  390. Solar activity for radio amateurs
  391. Solar conditions affect HF radio propagation
  392. Solar conditions and HF radio propagation
  393. Solar cycle
  394. Solar Cycle Ham Radio
  395. Solar data
  396. Solar electromagnetic spectrum
  397. Solar events
  398. Solar energetic Particle (SEP)
  399. Solar events
  400. Solar flares
  401. Solar flux index (SFI)
  402. Solar flux today
  403. Solar Ham
  404. Solar indices
  405. Solar observations
  406. Solar maximum
  407. Solar minimum
  408. Solar Particle event (SPE)
  409. Solar phenomena
  410. Solar radiation
  411. Solar radiation storms (flares); S1-5 scale
  412. Solar radio flux
  413. Solar spectra
  414. Solar storms
  415. Solar Storms Ham Radio
  416. Solar synoptic map
  417. Solar terminator (i.e. Greyline)
  418. Solar wind; The impact of the solar wind on HF radio transmission.
  419. Solar wind reports
  420. Solar X-Ray (Phenomenon)
  421. Solar X-ray Imaging system (SXI)
  422. Solar X-Ray flux levels
  423. Space wave
  424. Space Weather
  425. Space weather data and plots
  426. Space weather definitions and explanations
  427. Space weather events
  428. Space weather forecasts
  429. Space weather ground-based observatories
  430. Space weather observations
  431. Space weather observations from satellites
  432. Space weather prediction
  433. Space weather prediction center (NOAA)
  434. Space Weather predictions for radio amateurs
  435. Space weather reports
  436. Space weather scales
  437. SPE
  438. Spread F
  439. Sudden ionospheric disturbances
  440. Sunspots
  441. SuperDARN
  442. SWPC = Space Weather prediction center (NOAA)
  443. Sporadic e
  444. Stratosphere
  445. Sudden ionospheric disturbances (SID)
  446. Sunlight
  447. Sunspots
  448. Sunspot cycle
  449. Sunspot number (SSN)
  450. Sunspots recent days
  451. Sunspots today
  452. Surface wave propagation
  453. Space Weather prediction center (NOAA)

    T
  454. T Index map
  455. TEC - Total electron content
  456. Terminator line
  457. Terrestrial geomagnetic indices
  458. Terrestrial observations
  459. The Rebirth of Shortwave radio communication
  460. The recent HF propagation conditions
  461. The recent propagation conditions
  462. The recent skywave propagation conditions
  463. The Super Dual Auroral Radar Network (SuperDARN)
  464. Thermosphere
  465. TID (Traveling ionospheric disturbances)
  466. Tools for analyzing and forecasting HF propagation
  467. Total electron content — TEC
  468. Transmission Angle
  469. Traveling ionospheric disturbances (TID)
  470. Troposphere
  471. Twilight zone

    U
  472. Ultraviolet
  473. Understanding Ham bands conditions banner
  474. Understanding Ham radio propagation
  475. Understanding HF propagation
  476. Understanding HF Propagation
  477. Understanding HF propagation Numbers
  478. Understanding HF radio propagation
  479. Understanding LUF and MUF
  480. Understanding NVIS
  481. Understanding Skywave propagation
  482. Understanding the basics of HF band conditions
  483. Usable Frequency Range from LUF to MUF
  484. Usable HF frequencies
  485. Using HF beacon tracking programs

    V
  486. Variations in HF radio propagation
  487. Very High frequency (VHF)
  488. Very Low frequency (VLF)
  489. VHF propagation map
  490. View HF bands conditions at a glance
  491. Visualizing HF propagation
  492. VOACAP

    W
  493. Wave propagation
  494. What is Radio?
  495. What is Space weather?
  496. What is the current LUF?
  497. What is the current minimum useable frequency?
  498. What is the current Maximum Frequency?
  499. What is the current MUF?
  500. Wide-band WebSDR
  501. Window of useful frequencies from LUF to MUF
  502. World-wide Space Weather agencies & services
  503. Worldwide LUF Chart
  504. WSPR - Weak Signal propagation reporter * WSPR Live * WSPR Rocks * WSPRnet

    X
  505. X-Ray flares
  506. X-Ray flux levels (scale)

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