What can be seen is that the noise floor drops from ~59 to ~49 to ~47 for the three receivers (-98.5dB, -103.5dB, -104.5dB).<\/p>\n
The noise floor drops by 6 dB with the best antenna.<\/p><\/blockquote>\n
This gains is impressive and enables the reception of much weaker signals. The transmit-ON level varies a lot more. As the height of the antenna’s above the working surface differed somewhat, those figures are less trustworthy. In fact further experiments showed that with careful antenna positioning signal-ON levels are comparable over antenna design, while noise levels (signal-OFF) are always in the range of the reported values above.<\/p>\n
Finally it is good to move the antenna away from the microcontroller or microcomputer used. Moving away the Nucleo STM32 80cm while keeping the Conrad antenna at the same position<\/p>\n
Conrad, Nucleo 80cm away<\/h4>\n
30893 5 1 FS20 88400031214C (45\/98)
\n 30954 61 2 FS20 88400031214C (44\/94)
\n 31016 62 3 FS20 88400031214C (44\/91)<\/p>\n 36086 5 1 FS20 88400031214C (46\/92)
\n 36147 61 2 FS20 88400031214C (47\/93)
\n 36209 62 3 FS20 88400031214C (44\/92)
\nRSSI: 46(v 40-s 7-m134) THD:fix\/peak\/maxp:61\/61\/122
\n<\/code>
\nThe noise floor is now around 45 (=100.5dB), an gain of 7dB!<\/p>\n","protected":false},"excerpt":{"rendered":"
The antenna design of a module like the RFM69 is important for the sensitivity to sognal and noise. Also antenna positioning is important. Putting an Nucleo STM32 with RFM69CW very close to a PC will result in a increase of several dBm’s in noise floor. Gain 7 dB sensitivity with JeeNodes The basic antenna design […]<\/p>\n","protected":false},"author":1,"featured_media":514,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_mi_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"footnotes":""},"categories":[12,7,15],"tags":[50,38,45,28,33,58,51,52,49,46],"class_list":["post-525","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-jeenode","category-ook","category-rfm69","tag-antenna","tag-jeelib","tag-jeelink","tag-jeenode","tag-nucleo","tag-ook","tag-quarte-wavelength","tag-quarter-lambda","tag-rfm69","tag-stm32"],"_links":{"self":[{"href":"https:\/\/www.sevenwatt.com\/main\/wp-json\/wp\/v2\/posts\/525","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.sevenwatt.com\/main\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.sevenwatt.com\/main\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.sevenwatt.com\/main\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.sevenwatt.com\/main\/wp-json\/wp\/v2\/comments?post=525"}],"version-history":[{"count":8,"href":"https:\/\/www.sevenwatt.com\/main\/wp-json\/wp\/v2\/posts\/525\/revisions"}],"predecessor-version":[{"id":578,"href":"https:\/\/www.sevenwatt.com\/main\/wp-json\/wp\/v2\/posts\/525\/revisions\/578"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.sevenwatt.com\/main\/wp-json\/wp\/v2\/media\/514"}],"wp:attachment":[{"href":"https:\/\/www.sevenwatt.com\/main\/wp-json\/wp\/v2\/media?parent=525"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.sevenwatt.com\/main\/wp-json\/wp\/v2\/categories?post=525"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.sevenwatt.com\/main\/wp-json\/wp\/v2\/tags?post=525"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
![\"quarterwavelengthantenna\"](\"\/\/www.sevenwatt.com\/main\/wp-content\/uploads\/2015\/06\/quarterwavelengthantenna.png\")
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