{"id":5013,"date":"2018-06-03T11:46:00","date_gmt":"2018-06-03T01:46:00","guid":{"rendered":"https:\/\/www.homebrewradio.us\/blog\/2018\/06\/03\/understanding-antenna-directivity-help-from-canada\/"},"modified":"2018-06-03T11:46:00","modified_gmt":"2018-06-03T01:46:00","slug":"understanding-antenna-directivity-help-from-canada","status":"publish","type":"post","link":"https:\/\/www.homebrewradio.us\/blog\/2018\/06\/03\/understanding-antenna-directivity-help-from-canada\/","title":{"rendered":"Understanding Antenna Directivity &#8212; Help from Canada"},"content":{"rendered":"<p><iframe loading=\"lazy\" allow=\"autoplay; encrypted-media\" allowfullscreen=\"\" frameborder=\"0\" height=\"247\" src=\"https:\/\/www.youtube.com\/embed\/md7GjQQ2YA0?rel=0\" width=\"440\"><\/iframe><\/p>\n<p> <b>I am in the process of repairing my beloved 17 meter fishing-pole Moxon. It was taken out of service by the last Nor&#8217;easter of the winter. This repair has caused me to review the theory behind antenna directivity. I find there is a lot of &#8220;hand waving&#8221; in the explanations of how directivity happens: &#8220;You put a reflector element next to the antenna. And it REFLECTS!&#8221; You are left wondering how that reflection happens. <\/b><br \/> <b><br \/><\/b> <b>The Royal Canadian Air Force made a video that does a pretty good job of explaining how the reflector reflects. See above. Thanks Canada! <\/b><br \/> <b><br \/><\/b> <b>While we are talking about antennas, I wanted to alert readers to a really nice antenna modeling program that is available for free. It is called 4nec2. You can find it here: <\/b><br \/> <b><a href=\"http:\/\/www.qsl.net\/4nec2\/\">http:\/\/www.qsl.net\/4nec2\/<\/a> <\/b><b> There is a bit of a learning curve, and I am still climbing it, but I can see how this software would be very useful. It has an optimization feature that runs the antenna through many versions and tells you how to optimize for F\/B, gain, SWR, or whatever you want to prioritize. <\/b><br \/> <b><br \/><\/b> <b>I have discovered that my Moxon was resonant below the 17 meter band. In other words, the antenna elements were too big. About 3.6% too big according to my calculations. This may be the result of my using insulated wire for the antenna elements. Apparently the MOXGEN software assumes the use of uninsulated wire. I&#8217;m thinking that an easy way to deal with this would be to use the frequency 3.6% above my target frequency and then use the dimensions given my the MOXGEN program. Any thoughts on this plan? <\/b><br \/> <b><br \/><\/b> <b>What a shame that Cebik&#8217;s web sites have all disappeared. <\/b><\/p>\n","protected":false},"excerpt":{"rendered":"<p>I am in the process of repairing my beloved 17 meter fishing-pole Moxon. It was taken out of service by the last Nor&#8217;easter of the winter. This repair has caused me to review the theory behind antenna directivity. I find there is a lot of &#8220;hand waving&#8221; in the explanations of how directivity happens: &#8220;You &hellip; <a href=\"https:\/\/www.homebrewradio.us\/blog\/2018\/06\/03\/understanding-antenna-directivity-help-from-canada\/\" class=\"more-link\">Continue reading<span class=\"screen-reader-text\"> &#8220;Understanding Antenna Directivity &#8212; Help from Canada&#8221;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[69,180,27,143],"tags":[],"class_list":["post-5013","post","type-post","status-publish","format-standard","hentry","category-antennas","category-moxon","category-propagation","category-software"],"_links":{"self":[{"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/posts\/5013","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/comments?post=5013"}],"version-history":[{"count":0,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/posts\/5013\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/media?parent=5013"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/categories?post=5013"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/tags?post=5013"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}