↑ Terms 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 reflects 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. Blackouts; R1-5 scale
  20. Blind zone
  21. Bt - total strength of the Interplanetary Magnetic field (IMF)
  22. Bz - orientation of the IMF

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

    D
  53. DX propagation map
  54. DX propagation online map
  55. DX propagation prediction
  56. DXMAPS
  57. DXWatch
  58. DXZone

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

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

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

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


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

    K
  217. K-Index
  218. Key Factors Affecting HF Propagation
  219. Kp index
  220. KiwiSDR map of remote public SDR receivers accessible via the Internet

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

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

    N
  249. Near real-time regional maps
  250. NOAA National Oceanic and Atmospheric Administration
  251. Noise level
  252. NVIS
  253. NVIS map
  254. NVIS propagation
  255. NVIS tutorial

    O
  256. Observations - Geo (Terrestrial) & Solar
  257. On-Line HF propagation prediction
  258. Online propagation tools
  259. Online real-time propagation charts
  260. Optimal Sending frequency
  261. OWF - Optimum Working frequency

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

    Q
  294. Quick guide to HF propagation using solar indices

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

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

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

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

    V
  471. Variations in HF radio propagation
  472. Very High frequency (VHF)
  473. Very Low frequency (VLF)
  474. VHF propagation map
  475. View HF bands conditions at a glance
  476. Visualizing HF propagation
  477. VOACAP

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

    X
  490. X-Ray flares
  491. X-Ray flux levels (scale)
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