Every time I have to figure out ERP or dB gain I always have to search the Internet to find the formulas. Well, I figured I could just look them up here if I posted them, so here they are!<\/p>\n\n\n\n
Calculate dB gain based on actual output change. This is good for working out how much gain and amplifier gives you:\n\n10 X log(power\/refpower) = dBm Gain \/ loss\n\nExample using 65 Watt output from radio into an amp and seeing that the output power is 500 Watts.\n\n10 X log(500\/65) = 8.86 dBm gain\n\nCalculate dBm from output power:\n\n10 X log(1000 X output watts) = Total DB Output\n\nExample using a 100 Watt output.\n\n10 X log(1000 X 100) = 50 dBm Output\n\nCalculate output power from dBm\n\n10^(dBm\/ 10) \/ 1000\n\nCalculate ERP based on radio output and Antenna gain:\n\nRadio Power * 10^(dBm gain\/10) = ERP\n\nExample using 100 Watts radio output and a dB gain of 9 dBm from the antenna system:\n\n100 * 10^(9\/10) = 794 Watts\n\nCalculate percentage of gain or loss based on dB\n\n1 - (10^((-(dBm Loss\/10)))) = Percentage of Loss\n\n10^(dBm Gain\/10) = Percentage of Gain\n\nExample using a 3 dBm loss and gain:\n\nLoss:\n1 - (10^((-(3\/10)))) = 50%\n\nGain:\n10^(3\/10) = 200%\n\nCalculate SWR Power Loss Percentage:\n(SWR -1 )\u00b2 \/ (SWR + 1)\u00b2 = Percentage of Loss\n\nPower and Attenuation Calculations:\n(all voltages are RMS)\n\nDrop in dBm = 20 x log(R1 \/ R2)\nExample: 50dBm = 20 x log(8000 \/ 25)\n\nR1 = 10^(dBm \/ 20) x R2\nV = \u221a(Watts x 50\u03a9)\nWatts = V\u00b2 \/ 50\u03a9\nWatts Required = V\u00b2 \/ R1\n\nBulletin 65 Formulas:\n\nPower Density:\nS = PG \/ 4\u03c0R\u00b2\nWhere:\nS = power density as mW\/cm2\nP = power at input of antenna\nG = power gain of antenna in the direction of interest\nR = distance to the center of the radiation of antenna\n\nMax Power for Distance:\nMax Power Density X (4\u03c0 X (Distance\u00b2) = Max Power\n\nMinimum Distance:\nSquare Of((Power \/ Max PD) \/ (4\u03c0))\n\nAdding for Reflection:\nERP X (1.6)\u00b2\n\nThere are the two I use all the time. These two also serve as a really good platform for all sorts of calculations. One note, if you are looking for Voltage Gain, change the base 10 to base 20.<\/pre>\n\n\n\n— Stu<\/p>\n\n\n\n
<\/p>\n","protected":false},"excerpt":{"rendered":"
Every time I have to figure out ERP or dB gain I always have to search the Internet to find the formulas. Well, I figured I could just look them up here if I posted them, so here they are! Calculate dB gain based on actual output change. This is good for working out how […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[198,211],"tags":[203,202],"class_list":["post-1623","post","type-post","status-publish","format-standard","hentry","category-amateur-radio","category-radio-sport","tag-amateur-radio","tag-ham-radio"],"_links":{"self":[{"href":"https:\/\/www.stuartsheldon.org\/blog\/wp-json\/wp\/v2\/posts\/1623","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.stuartsheldon.org\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.stuartsheldon.org\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.stuartsheldon.org\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.stuartsheldon.org\/blog\/wp-json\/wp\/v2\/comments?post=1623"}],"version-history":[{"count":11,"href":"https:\/\/www.stuartsheldon.org\/blog\/wp-json\/wp\/v2\/posts\/1623\/revisions"}],"predecessor-version":[{"id":1709,"href":"https:\/\/www.stuartsheldon.org\/blog\/wp-json\/wp\/v2\/posts\/1623\/revisions\/1709"}],"wp:attachment":[{"href":"https:\/\/www.stuartsheldon.org\/blog\/wp-json\/wp\/v2\/media?parent=1623"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.stuartsheldon.org\/blog\/wp-json\/wp\/v2\/categories?post=1623"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.stuartsheldon.org\/blog\/wp-json\/wp\/v2\/tags?post=1623"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}