{"id":2916,"date":"2024-03-08T12:25:15","date_gmt":"2024-03-08T12:25:15","guid":{"rendered":"https:\/\/m0aws.co.uk\/?p=2916"},"modified":"2024-03-08T12:25:15","modified_gmt":"2024-03-08T12:25:15","slug":"stray-capacitance-effects-on-swr-at-868mhz","status":"publish","type":"post","link":"https:\/\/m0aws.co.uk\/?p=2916","title":{"rendered":"Stray capacitance effects on SWR at 868Mhz"},"content":{"rendered":"\n

Following on from my last article on improving the Heltec ESP32 v3 antennas<\/a> I found during the installation of the 90 degree SMA connector that the device was very sensitive to stray capacitance from things around it. After reconnecting my VNA<\/a> I found the SWR curve would change substantially depending on what the device was near and so I set about rectifying this.<\/p>\n\n\n\n

I decided to remove all the insulation from the single radial inside the unit and then added two more radials to increase the ground for the antenna to tune against. I then removed the N type plug with the antenna connected to it and made a new antenna from a piece of 1.5mm solid core insulated mains wire connected directly to the N type socket, without using an N type plug. Tuning to resonance was much easier than before and I soon had the SWR down to 1.2:1. Moving the device around and placing near to other objects the SWR curve was now much more stable than before with only very slight changes in curve shape.<\/p>\n\n\n\n

\"M0AWS
M0AWS Updated 868Mhz Antenna<\/figcaption><\/figure>\n\n\n\n

Making this change to the 868Mhz antenna has shown an improvement in signal strength from my node-1 device of almost +0.5dB, every dB counts when you only have 100mW to play with!<\/p>\n\n\n\n

The Bluetooth antenna update has made a massive improvement to the usability of the device via the iOS Meshtastic<\/a> app. Being able to have a reliable, solid connection from anywhere in the house is great and I no longer lose messages because I’ve strayed outside the range of the Bluetooth connection.<\/p>\n\n\n\n

I now have 2 new Heltec ESP32 v3 devices<\/a> on the way to me and will be getting those configured and operational outside with external antennas in the hope of hearing some nodes locally to me.<\/p>\n\n\n\n

More soon …<\/p>\n","protected":false},"excerpt":{"rendered":"

Following on from my last article on improving the Heltec ESP32 v3 antennas I found during the installation of the 90 degree SMA connector that the device was very sensitive to stray capacitance from things around it. After reconnecting my VNA I found the SWR curve would change substantially depending on what the device was … <\/p>\n

Continue reading “Stray capacitance effects on SWR at 868Mhz”<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[276,6,274,280,20,282,4,271,285,65,254,272,186,130,227,17,106],"tags":[],"class_list":["post-2916","post","type-post","status-publish","format-standard","hentry","category-868mhz","category-antenna","category-bender","category-bluetooth","category-digitalmodes","category-esp32","category-ham-radio","category-heltec","category-heltecesp32v3","category-home-brew","category-impedance","category-meshtastic","category-nodes","category-qrpp","category-swr","category-weak-signals","category-wireless"],"_links":{"self":[{"href":"https:\/\/m0aws.co.uk\/index.php?rest_route=\/wp\/v2\/posts\/2916","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/m0aws.co.uk\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/m0aws.co.uk\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/m0aws.co.uk\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/m0aws.co.uk\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=2916"}],"version-history":[{"count":6,"href":"https:\/\/m0aws.co.uk\/index.php?rest_route=\/wp\/v2\/posts\/2916\/revisions"}],"predecessor-version":[{"id":2923,"href":"https:\/\/m0aws.co.uk\/index.php?rest_route=\/wp\/v2\/posts\/2916\/revisions\/2923"}],"wp:attachment":[{"href":"https:\/\/m0aws.co.uk\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2916"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/m0aws.co.uk\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=2916"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/m0aws.co.uk\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=2916"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}