{"id":5382,"date":"2025-03-31T17:38:15","date_gmt":"2025-03-31T21:38:15","guid":{"rendered":"https:\/\/w2so.org\/?page_id=5382"},"modified":"2025-03-31T17:49:13","modified_gmt":"2025-03-31T21:49:13","slug":"hf-propagation-basics","status":"publish","type":"page","link":"https:\/\/w2so.org\/index.php\/hf-propagation-basics\/","title":{"rendered":"HF Radio Propagation Basics"},"content":{"rendered":"<h1 class=\"\" data-start=\"62\" data-end=\"91\"><\/h1>\n<h2 class=\"\" data-start=\"138\" data-end=\"170\"><strong data-start=\"141\" data-end=\"168\">What is HF Propagation?<\/strong><\/h2>\n<p class=\"\" data-start=\"171\" data-end=\"351\">Without propagation, all radio communication would be limited to line-of-sight. Unlike VHF and UHF, HF (10M-160M) interacts with the atmosphere, enabling long-distance communication.<\/p>\n<h2 class=\"\" data-start=\"353\" data-end=\"382\"><strong data-start=\"356\" data-end=\"380\">Why is HF Different?<\/strong><\/h2>\n<ul data-start=\"383\" data-end=\"564\">\n<li class=\"\" data-start=\"383\" data-end=\"477\">\n<p class=\"\" data-start=\"385\" data-end=\"477\">Lower frequencies mean longer wavelengths, which interact with the ionosphere differently.<\/p>\n<\/li>\n<li class=\"\" data-start=\"478\" data-end=\"564\">\n<p class=\"\" data-start=\"480\" data-end=\"564\">HF propagation depends on many various factors, including frequency, solar activity, and time of day.<\/p>\n<\/li>\n<\/ul>\n<h2 class=\"\" data-start=\"566\" data-end=\"608\"><strong data-start=\"569\" data-end=\"606\">Key Factors Affecting Propagation<\/strong><\/h2>\n<ul data-start=\"609\" data-end=\"830\">\n<li class=\"\" data-start=\"609\" data-end=\"675\">\n<p class=\"\" data-start=\"611\" data-end=\"675\"><strong data-start=\"611\" data-end=\"625\">Frequency:<\/strong> Determines range and time-of-day effectiveness.<\/p>\n<\/li>\n<li class=\"\" data-start=\"676\" data-end=\"753\">\n<p class=\"\" data-start=\"678\" data-end=\"753\"><strong data-start=\"678\" data-end=\"692\">Grey Line:<\/strong> The transition between night and day enhances propagation.<\/p>\n<\/li>\n<li class=\"\" data-start=\"754\" data-end=\"830\">\n<p class=\"\" data-start=\"756\" data-end=\"830\"><strong data-start=\"756\" data-end=\"771\">Ionosphere:<\/strong> The upper part of Earth&#8217;s atmosphere which refracts and reflects HF radio waves back to earth. It is Influenced by sunspots, K-index, solar storms, and CMEs.<\/p>\n<\/li>\n<\/ul>\n<h2 class=\"\" data-start=\"832\" data-end=\"857\"><strong data-start=\"835\" data-end=\"855\">Useful Resources<\/strong><\/h2>\n<ul data-start=\"858\" data-end=\"1068\">\n<li class=\"\" data-start=\"858\" data-end=\"989\">\n<p class=\"\" data-start=\"860\" data-end=\"989\"><strong data-start=\"860\" data-end=\"873\">Websites:<\/strong> <a class=\"\" href=\"https:\/\/www.hamqsl.com\/solar.html\" target=\"_new\" rel=\"noopener\" data-start=\"874\" data-end=\"921\">hamqsl.com<\/a>, <a class=\"\" href=\"https:\/\/prop.kc2g.com\" target=\"_new\" rel=\"noopener\" data-start=\"923\" data-end=\"961\">prop.kc2g.com<\/a> for real-time solar data.<\/p>\n<\/li>\n<li class=\"\" data-start=\"990\" data-end=\"1068\">\n<p class=\"\" data-start=\"992\" data-end=\"1068\"><strong data-start=\"992\" data-end=\"1005\">Software:<\/strong> VOAProp (signal strength maps), HamClock (Linux &amp; Rasp. Pi App).<\/p>\n<\/li>\n<\/ul>\n<h2 class=\"\" data-start=\"1070\" data-end=\"1099\"><strong data-start=\"1073\" data-end=\"1097\">Choosing a Frequency<\/strong><\/h2>\n<p class=\"\" data-start=\"1100\" data-end=\"1166\">The best frequency to use depends on location, time, and solar conditions. General trends:<\/p>\n<ul data-start=\"1167\" data-end=\"1301\">\n<li class=\"\" data-start=\"1167\" data-end=\"1222\">\n<p class=\"\" data-start=\"1169\" data-end=\"1222\"><strong data-start=\"1169\" data-end=\"1203\">Below 10 MHz (&#8220;Vampire Bands&#8221;)<\/strong> \u2013 Best at night.<\/p>\n<\/li>\n<li class=\"\" data-start=\"1223\" data-end=\"1301\">\n<p class=\"\" data-start=\"1225\" data-end=\"1301\"><strong data-start=\"1225\" data-end=\"1258\">Above 10 MHz (&#8220;Farmer Bands&#8221;)<\/strong> \u2013 Favor daylight, dependent on sunspots.<\/p>\n<\/li>\n<\/ul>\n<h2 class=\"\" data-start=\"1303\" data-end=\"1325\"><strong data-start=\"1306\" data-end=\"1323\">Band Overview<\/strong><\/h2>\n<ul data-start=\"1326\" data-end=\"1837\">\n<li class=\"\" data-start=\"1326\" data-end=\"1411\">\n<p class=\"\" data-start=\"1328\" data-end=\"1411\"><strong data-start=\"1328\" data-end=\"1351\">160M (1.8-2.0 MHz):<\/strong> Short-range by day, long-range at night, noisy in summer.<\/p>\n<\/li>\n<li class=\"\" data-start=\"1412\" data-end=\"1500\">\n<p class=\"\" data-start=\"1414\" data-end=\"1500\"><strong data-start=\"1414\" data-end=\"1439\">75-80M (3.5-4.0 MHz):<\/strong> Local during the day, long-range at night, great for NVIS.<\/p>\n<\/li>\n<li class=\"\" data-start=\"1501\" data-end=\"1596\">\n<p class=\"\" data-start=\"1503\" data-end=\"1596\"><strong data-start=\"1503\" data-end=\"1519\">60M (5 MHz):<\/strong> Medium-range by day, long-range at night, shared with government\/military.<\/p>\n<\/li>\n<li class=\"\" data-start=\"1597\" data-end=\"1669\">\n<p class=\"\" data-start=\"1599\" data-end=\"1669\"><strong data-start=\"1599\" data-end=\"1621\">40M (7.0-7.3 MHz):<\/strong> Local\/regional by day, excellent DX at night.<\/p>\n<\/li>\n<li class=\"\" data-start=\"1670\" data-end=\"1740\">\n<p class=\"\" data-start=\"1672\" data-end=\"1740\"><strong data-start=\"1672\" data-end=\"1697\">30M (10.1-10.15 MHz):<\/strong> Digital\/CW only, consistent propagation.<\/p>\n<\/li>\n<li class=\"\" data-start=\"1741\" data-end=\"1837\">\n<p class=\"\" data-start=\"1743\" data-end=\"1837\"><strong data-start=\"1743\" data-end=\"1776\">20M (14.0-14.35 MHz) &amp; Above:<\/strong> Primarily daytime bands, dependent on MUF and solar cycle.<\/p>\n<\/li>\n<\/ul>\n<h2 class=\"\" data-start=\"1839\" data-end=\"1855\"><strong data-start=\"1842\" data-end=\"1853\">Summary<\/strong><\/h2>\n<p class=\"\" data-start=\"1856\" data-end=\"2003\">By understanding propagation trends and solar conditions, you can always find an open band. Experience makes prediction easier\u2014so get on the air!<\/p>\n<hr \/>\n<h2 data-start=\"1856\" data-end=\"2003\"><strong>More Resources<\/strong><\/h2>\n<p><a href=\"https:\/\/w2so.org\/wp-content\/uploads\/2025\/03\/Something-is-open.pdf\">Here&#8217;s a link to the slide show presentation file that was used to write this guide up, courtesy of Steve AG2AA<\/a><\/p>\n<p><a href=\"https:\/\/solar.w5mmw.net\/\">Here&#8217;s a link to the easy-to-read Solar Conditions &amp; Ham Radio Propagation, Courtesy of W5MMW<\/a><\/p>\n<p><a href=\"https:\/\/pskreporter.info\/\">Digimode Automatic Propagation Reporter &#8211; PSKReporter<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>What is HF Propagation? Without propagation, all radio communication would be limited to line-of-sight. Unlike VHF and UHF, HF (10M-160M) interacts with the atmosphere, enabling &hellip; <a title=\"HF Radio Propagation Basics\" class=\"bnm-read-more\" href=\"https:\/\/w2so.org\/index.php\/hf-propagation-basics\/\"><span class=\"screen-reader-text\">HF Radio Propagation Basics<\/span>Read more<\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_mc_calendar":[],"footnotes":""},"class_list":["post-5382","page","type-page","status-publish","hentry","bnm-entry"],"_links":{"self":[{"href":"https:\/\/w2so.org\/index.php\/wp-json\/wp\/v2\/pages\/5382","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/w2so.org\/index.php\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/w2so.org\/index.php\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/w2so.org\/index.php\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/w2so.org\/index.php\/wp-json\/wp\/v2\/comments?post=5382"}],"version-history":[{"count":4,"href":"https:\/\/w2so.org\/index.php\/wp-json\/wp\/v2\/pages\/5382\/revisions"}],"predecessor-version":[{"id":5387,"href":"https:\/\/w2so.org\/index.php\/wp-json\/wp\/v2\/pages\/5382\/revisions\/5387"}],"wp:attachment":[{"href":"https:\/\/w2so.org\/index.php\/wp-json\/wp\/v2\/media?parent=5382"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}