{"id":15936,"date":"2025-11-19T07:50:28","date_gmt":"2025-11-19T02:20:28","guid":{"rendered":"https:\/\/johnsonfrancis.org\/techworld\/?p=15936"},"modified":"2025-11-19T07:50:29","modified_gmt":"2025-11-19T02:20:29","slug":"how-high-is-rf-voltage-at-ends-of-dipole-antenna-running-100w","status":"publish","type":"post","link":"https:\/\/johnsonfrancis.org\/techworld\/how-high-is-rf-voltage-at-ends-of-dipole-antenna-running-100w\/","title":{"rendered":"How high is RF voltage at ends of dipole antenna running 100W?"},"content":{"rendered":"<iframe loading=\"lazy\" width=\"560\" height=\"315\" src=\"https:\/\/www.youtube.com\/embed\/eqpJ77Vg2bk?si=Lde7jdXkipgOv0CU\" title=\"YouTube video player\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe>\n\n<p class=\"wp-block-paragraph\">While learning the basics of inverted V dipole antenna, we are asked to keep the ends of the antenna out of reach for humans and animals. The reason is that the antenna RF voltage is highest at its ends for a dipole. Direct contact with a live antenna can cause difficult to heal RF burns. We will look at a simple calculation of approximate voltage of a dipole antenna with impedance of around 73\u03a9, running 100W power from the radio. Feedpoint impedance of inverted V may be lower at about 50\u03a9. RF voltage at the feed point will be lowest. For resonant dipole antenna, the impedance at the ends will be high, of the order of 4000\u03a9, similar to the feed point impedance of an end fed half-wave dipole antenna.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">We know that P = (V<sub>RMS<\/sub>)<sup>2<\/sup>\/Z, where P is the power, V<sub>RMS<\/sub> the root mean square voltage and Z the impedance. Rearranging, we get V<sub>RMS<\/sub> = \u221a(P*Z) = \u221a(100W * 73\u03a9) = 85.44V, at the feed point with impedance 73\u03a9. Peak voltage at the feed point will be 85.44V * \u221a2 = 120.8V.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">If the impedance at the tip of the dipole antenna is 4000\u03a9:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">V<sub>Peak<\/sub> = \u221a(P*Z) * \u221a2 = \u221a(100W * 4000\u03a9) * \u221a2 = 632.46 *  \u221a2 = 894.4 V<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Now you can get an idea about the importance of keeping the ends of the dipole well insulated and out of reach of human beings and animals! This calculation is based on the situation at 1:1 VSWR and presumed impedance of dipole at the end of 4000\u03a9, though it may vary from 1800\u03a9 to 5000\u03a9. <\/p>\n","protected":false},"excerpt":{"rendered":"<p>While learning the basics of inverted V dipole antenna, we are asked to keep the ends of the antenna out of reach for humans and animals. The reason is that the antenna RF voltage is highest at its ends for a dipole. Direct contact with a live antenna can cause difficult to heal RF burns. [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":15938,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[],"class_list":["post-15936","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-amateur-radio-ham-radio"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.8 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>How high is RF voltage at ends of dipole antenna running 100W? - Johnson&#039;s Techworld<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/johnsonfrancis.org\/techworld\/how-high-is-rf-voltage-at-ends-of-dipole-antenna-running-100w\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"How high is RF voltage at ends of dipole antenna running 100W? - Johnson&#039;s Techworld\" \/>\n<meta property=\"og:description\" content=\"While learning the basics of inverted V dipole antenna, we are asked to keep the ends of the antenna out of reach for humans and animals. 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