{"id":45,"date":"2015-01-23T20:13:34","date_gmt":"2015-01-24T03:13:34","guid":{"rendered":"http:\/\/ve6sar.northernsmiths.ca\/?p=45"},"modified":"2015-03-12T13:25:00","modified_gmt":"2015-03-12T20:25:00","slug":"uhf-hentenna","status":"publish","type":"post","link":"https:\/\/ve6sar.northernsmiths.ca\/?p=45","title":{"rendered":"UHF Hentenna"},"content":{"rendered":"

I wanted a portable some what directional UHF antenna that I could use for path testing for linking for some time and after looking over a bunch of different Google search results I decided to try making a Hentenna. The Hentenna from the research I’ve done has 2 – 3 dbd gain in a bi-directional pattern. The directions I based my build on are located at Ham Universe<\/a>.<\/p>\n

They give you the formulas for the dimensions and the lay out.<\/p>\n

I had a piece of 1\/4″ copper tubing sitting around so I figured for my first attempt at a Hentenna it would work great.<\/p>\n

For the actual I didn’t have a tubing bender handy at the time but I did have some 3\/16″ stainless steel cable that I fed through the tube to keep it from collapsing when I bent the tube into the rectangular shape of the antenna.<\/p>\n

My first bend was at 5.6mm from one end (half of the short side distance) then worked my way around until I completed all four bends. Then I verified the short side length and cut the extra copper tubing off the end so that when the two ends but together I got 11.2mm centre to centre.<\/p>\n

I joined the two ends by inserting a short piece of #12 stranded bare copper wire in the tube to provide some rigidity while I soldered the to end together.<\/p>\n

For the feed point I cut a length of #14 bare copper wire and laid it across the antenna at the calculated feed point location and curled the ends around the tubing.<\/p>\n

I then marked the centre point of #14 copper wire.<\/p>\n

On the coax feed line I stripped back approximately 1″ of outer sheath then pulled back the braid and twisted off to one side. I striped about 3\/8″ of the centre conductor.<\/p>\n

I formed the end of the coax into a “T” shape, centred the “T” on the #14 copper wire then soldered the shield and the centre conductor to the #14\u00a0wire. Once they where soldered I used my flush cutters to cut the #14 wire between the two solder joints out.<\/p>\n

\"s_hentenna-feed-point\"<\/p>\n

I tie wrapped the coax on the the antenna to relieve the strain on the feed points.<\/p>\n

\"s_hentenna-coax-tie\"<\/p>\n

Now it was time to tune the antenna.<\/p>\n

I used my antenna analyser to check the SWR of the antenna and I adjusted it for the minimum SWR at 446 mhz by sliding the #14 wires up slightly from the measured feed point. I was able to get less then 1.5 SWR across most of the band.<\/p>\n

\"s_hentenna-swr-10mhz\"<\/a>
\"s_hentenna-swr-100mhz\" 10 mHz and 100 mHz scan widths centred on 446 mHz<\/figcaption><\/figure>\n

 <\/p>\n

After tuning I soldered the 2 pieces of #14 wire to the 1\/4″ tubing then verified the antenna was still in tune.<\/p>\n

\"s_hentenna-feed-point-2\"<\/p>\n

Here’s the completed antenna.<\/p>\n

\"s_hentenna-complete-1\"<\/p>\n

For horizontal polarization mount the antenna on a non-conducting mount with the short sides at the top and bottom. For vertical polarization, mount the antenna with the short sides vertically.<\/p>\n

Initial testing shows that it is an improvement over a 1\/4″ wave ground plane antenna.<\/p>\n

 <\/p>\n

 <\/p>\n

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I wanted a portable some what directional UHF antenna that I could use for path testing for linking for some time and after looking over a bunch of different Google search results I decided to try making a Hentenna. The …<\/p>\n

UHF Hentenna<\/span> Read More »<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"jetpack_post_was_ever_published":false},"categories":[3],"tags":[],"class_list":["post-45","post","type-post","status-publish","format-standard","hentry","category-ham"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p4JDFz-J","_links":{"self":[{"href":"https:\/\/ve6sar.northernsmiths.ca\/index.php?rest_route=\/wp\/v2\/posts\/45","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ve6sar.northernsmiths.ca\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ve6sar.northernsmiths.ca\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ve6sar.northernsmiths.ca\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/ve6sar.northernsmiths.ca\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=45"}],"version-history":[{"count":5,"href":"https:\/\/ve6sar.northernsmiths.ca\/index.php?rest_route=\/wp\/v2\/posts\/45\/revisions"}],"predecessor-version":[{"id":57,"href":"https:\/\/ve6sar.northernsmiths.ca\/index.php?rest_route=\/wp\/v2\/posts\/45\/revisions\/57"}],"wp:attachment":[{"href":"https:\/\/ve6sar.northernsmiths.ca\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=45"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ve6sar.northernsmiths.ca\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=45"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ve6sar.northernsmiths.ca\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=45"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}