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

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

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

    D
  55. DX propagation map
  56. DX propagation online map
  57. DX propagation prediction
  58. DXMAPS
  59. DXWatch
  60. DXZone

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

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

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

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


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

    K
  220. K-Index
  221. Key Factors Affecting HF Propagation
  222. Kp index
  223. KiwiSDR map of remote public SDR receivers accessible via the Internet

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

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

    N
  251. Near real-time regional maps
  252. NET ionospheric model
  253. NOAA National Oceanic and Atmospheric Administration
  254. Noise level
  255. NVIS
  256. NVIS map
  257. NVIS propagation
  258. NVIS tutorial

    O
  259. Observations - Terrestrial & Solar
  260. On-Line HF propagation prediction
  261. Online propagation tools
  262. Online real-time propagation charts
  263. Optimal Sending frequency
  264. OWF - Optimum Working frequency

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

    Q
  298. Quick guide to HF propagation using solar indices

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

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

    T
  443. T Index map
  444. TEC - Total electron content
  445. Terminator line
  446. Terrestrial geomagnetic indices
  447. Terrestrial observations
  448. The Rebirth of Shortwave radio communication
  449. The recent HF propagation conditions
  450. The recent propagation conditions
  451. The recent skywave propagation conditions
  452. The Super Dual Auroral Radar Network (SuperDARN)
  453. Thermosphere
  454. TID (Traveling ionospheric disturbances)
  455. Tools for analyzing and forecasting HF propagation
  456. Total electron content — TEC
  457. Transmission Angle
  458. Traveling ionospheric disturbances (TID)
  459. Troposphere
  460. Twilight zone

    U
  461. Ultraviolet
  462. Understanding Ham bands conditions banner
  463. Understanding Ham radio propagation
  464. Understanding HF propagation
  465. Understanding HF Propagation
  466. Understanding HF propagation Numbers
  467. Understanding HF radio propagation
  468. Understanding LUF and MUF
  469. Understanding NVIS
  470. Understanding Skywave propagation
  471. Understanding the basics of HF band conditions
  472. Usable Frequency Range from LUF to MUF
  473. Usable HF frequencies
  474. Using HF beacon tracking programs

    V
  475. Variations in HF radio propagation
  476. Very High frequency (VHF)
  477. Very Low frequency (VLF)
  478. VHF propagation map
  479. View HF bands conditions at a glance
  480. Visualizing HF propagation
  481. VOACAP

    W
  482. Wave propagation
  483. What is Radio?
  484. What is Space weather?
  485. What is the current LUF?
  486. What is the current minimum useable frequency?
  487. What is the current Maximum Frequency?
  488. What is the current MUF?
  489. Wide-band WebSDR
  490. Window of useful frequencies from LUF to MUF
  491. World-wide Space Weather agencies & services
  492. Worldwide LUF Chart
  493. WSPR - Weak Signal propagation reporter * WSPR Live * WSPR Rocks * WSPRnet

    X
  494. X-Ray flares
  495. X-Ray flux levels (scale)

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