{"id":791,"date":"2019-02-13T11:30:47","date_gmt":"2019-02-13T16:30:47","guid":{"rendered":"http:\/\/badger-fi.com\/?p=791"},"modified":"2019-02-13T11:30:47","modified_gmt":"2019-02-13T16:30:47","slug":"nvis","status":"publish","type":"post","link":"https:\/\/www.badger-fi.com\/?p=791","title":{"rendered":"Near Vertical Incidence Skywave (NVIS) Antenna for Local HF Contacts"},"content":{"rendered":"

The Virginia QSO Party<\/a> is just around the corner and this year I am going to be better prepared for making local HF contacts.\u00a0 In the last few years of contesting, I have been plagued with poor local performance from my HF operating station.\u00a0 I employed two multi-band HF antennas for making contacts but found that I could mostly reach non-Virginia stations, typically > a 500 mile radius from my location.\u00a0 My current antenna setups are great for long distance contacts, often times reaching all over the US and Europe.\u00a0 The antennas are great for making DX contacts due to their take off angle, but not as great for local contacts for the same reason they are great for DX.\u00a0 My current HF station is comprised of an Icom 7300 HF radio, seven band off center fed (OCF)\u00a0Buckmaster dipole<\/a>, and six band MFJ 1796 vertical<\/a>.\u00a0 I can switch between antennas using an\u00a0LDG AT-100ProII antenna tuner<\/a> which also has an Alpha Delta antenna switch<\/a> hanging off the ANT2 connection (more to come on that later).\u00a0\u00a0A little research yielded interesting results and a positive outlook to my local contact problem.<\/p>\n

When researching my problem I found a solution that the military has used for a very long time to establish local coms with ground units using HF.\u00a0 They use a technique called Near Vertical Incidence Skywave (NVIS), which generally speaking, shoots the signal at an extreme angle into the air.\u00a0 The signal then bounces off of the Ionosphere and comes back to Earth, proving effective 30-500 miles from the originating station.\u00a0 This type of antenna is said to work best between 2 and 10 MHz (primarily 80m and 40m bands).\u00a0 Further research led me to a plan for an NVIS antenna that can be built easily and\u00a0 inexpensively.<\/p>\n

DX Engineering<\/a>, which is my favorite place to source my amateur radio needs, has a great PDF<\/a> that explains the technical details behind the NVIS antenna as well as the plan and parts list to build an antenna for yourself.\u00a0 Please check out the PDF<\/a> for a deeper technical explanation as well as the parts list.\u00a0 I ordered all the parts I needed to build an NVIS antenna and also purchased a very sturdy, telescoping fiberglass painters pole<\/a>\u00a0from Lowes to mount the antenna to.\u00a0 Once the parts were received, which for me usually only takes a day from DX Engineering (another reason I love them), I was able to assemble the entire antenna in an hour or so.\u00a0 The listed “kit” includes the assembly instructions which are easy to follow.\u00a0 I chose to only build the 40m NVIS dipole due to the location where I was going to be mounting it.<\/p>\n

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After assembly I attached the center “T” to my telescoping fiberglass pole and set it to a height of 15 feet.\u00a0 I mounted the fiberglass pole to a fence in my back yard which runs parallel with some evergreen trees that boarder my property.\u00a0 The pole extends upwards into the evergreen trees with it’s wire “legs” making an inverted “V”\u00a0 with the ends extending out and mounted roughly 3 feet off of the ground.\u00a0 This position is what I found to work best during testing after installation.\u00a0 Results may vary and should be tested to meet your needs.<\/p>\n

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After getting everything mounted and attached, I ran a new length of RG-8X into my basement and connected it to my Alpha Delta antenna switch.\u00a0 I tuned the Icom 7300 to the 40m band and put the LDG AT-100ProII through a tuning process to see how things turned out.\u00a0 According to the tuner, I achieved a 1.1 : 1<\/strong> SWR on 40m which is what I expected.\u00a0 Just for fun, I tuned to the\u00a0 80m band and ran the tuning process to see what would happen.\u00a0 I was pleasantly surprised to find that it tuned almost as perfect as 40m!\u00a0 Since I received such great results on 80m and 40m, I decided to try 20m\u00a0 and found that it tuned perfect there too (as well as a few more bands)!\u00a0 With that said, I do realize that this is not a formal antenna analyzer so other numbers may be off.\u00a0 Regardless, I was very happy that the NVIS antenna was tuned in and was working properly!<\/p>\n

Antenna building is a very fun part of the amateur radio hobby, especially when the expected results are so easily achieved.\u00a0 Not only was I able to build an effective antenna for very little cost, I was able to solve a problem that had been occurring for the last few years during the Virginia QSO Party.\u00a0 Next month will mark my 3rd Virginia QSO Party and I look forward to making contact with many local Virginia stations as well as out of state contacts with the new NVIS antenna!<\/p>\n

Look for me on the airwaves on March 16-17.<\/p>\n

73 de W4LAN<\/p>\n

If you have any comments or questions about my NVIS antenna, feel free to leave them in the comments section below.<\/p>\n

 <\/p>\n

**The Virginia QSO Party is sponsored by the Sterling Park Amateur Radio Club<\/a> (SPARC).<\/p>\n

**Although I am not affiliated with DX Engineering, I HIGHLY<\/strong> recommend them.\u00a0 They have great products (and prices that almost always beat Amazon<\/strong>), great information,\u00a0 and shipping is VERY fast!<\/p>\n","protected":false},"excerpt":{"rendered":"

The Virginia QSO Party is just around the corner and this year I am going to be better prepared for making local HF contacts.\u00a0 In the last few years of contesting, I have been plagued with poor local performance from my HF operating station.\u00a0 I employed two multi-band HF antennas for making contacts but found […]<\/p>\n","protected":false},"author":1,"featured_media":806,"comment_status":"open","ping_status":"open","sticky":true,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2],"tags":[17,20,29,49,50,67,69,71,72,76,95,101,110,111,112,128],"class_list":["post-791","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-amateur-radio","tag-antenna","tag-arrl","tag-buckmaster","tag-dx","tag-dx-engineering","tag-ham-radio","tag-hf","tag-icom","tag-icom-7300","tag-ldg-at-pro100ii","tag-near-vertical-incidence-skywave","tag-nvis","tag-qso","tag-qso-party","tag-radio","tag-virginia-qso-party"],"_links":{"self":[{"href":"https:\/\/www.badger-fi.com\/index.php?rest_route=\/wp\/v2\/posts\/791","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.badger-fi.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.badger-fi.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.badger-fi.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.badger-fi.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=791"}],"version-history":[{"count":0,"href":"https:\/\/www.badger-fi.com\/index.php?rest_route=\/wp\/v2\/posts\/791\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.badger-fi.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=791"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.badger-fi.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=791"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.badger-fi.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=791"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}