My Homemade 40-Meter NVIS Linear-Loaded Dipole for POTA
by Tom VE3YTN
(Ontario (FN04), Canada)
Center feed point
Left hand side
Right hand side
I want to thank you for the design of the NVIS portable antenna.
I built it to the dimensions given in your article (see reference link to the article below) but folded each end back about 9 inches then moved its resonance point to the middle of the band by trial and error.
I am including 3 pics of how I deployed the antenna for POTA. The first pic shows the center feedpoint held up with a stick against a tree.
Although my antenna is not resonant on 20, I did try it with a tuner and worked California with it from home (FN04).
I built mine with twin lead heavier stuff that I picked up from a ham sale.
I used the same BNC twin banana plug connector that is described in your article. I did not put any chokes on the coax as I didn't have any RF feedback issue.
I ran some tests at home using a 50 ft and a 25 ft section of coax between antenna and radio.
Compared to the 17 ft vertical on the truck I would say signals were 2-3 S-units better on this antenna. I was getting 58 & 59 reports pretty much all night till 9:30 and then they started to fade.
I think it is definitely a worthwhile antenna to explore for its simplicity and simple deployment. I'm going to look into building some for other bands in the future.
My recent POTA activations were done using this antenna. It's strung up between 2 trees about 6 feet off the ground (see photos).
I have made over 200 QSOs at 100w and tonight logged 23 QSOs using only 5 watts!
My main reason for building your NVIS design was to improve the local contacts. I'm amazed how well it works across the North-East and even Florida as well as getting local Ontario stations. Maybe propagation was just that good. Time will tell.
It is easy to build and setup. It is simple and does not tangle up in tree branches. It also doubles as a clothes line when not being used on POTA. LoL.
Here (below) is a recording that VA3BLV made on October 10, 2022 at 01:11 UTC (recorded off KiwiSDR software-defined receiver in Jumonville, PA, Grid FM09dw), while I was using your 40 meter linear-loaded antenna design on 7.220 MHz on a POTA activation of parc number VE0140 in Ontario.