12/20/2025 – After putting up a new HF antenna for longer distance communications, I have decided that I will also need to employ an HF NVIS antenna. My first thought here is to use an old faithful version of an elmer’s off-centerfed dipole at a very low level. That is until I seen this:
https://www.w9xt.com/page_radio_gadgets_nvis_antenna.html
Concept is pretty sound and is basically a moxon in design. Radiating element employs a reflector that is pointing upwards. I wonder if I can incorporate this reflector in my new HF antenna? I need to source some 200′ of ladder line for this project. I am 3D printing some supports for 450 ohm ladder line using these prints.
End supports: https://www.thingiverse.com/thing:3839334
Center supports: https://www.thingiverse.com/thing:3614287
As for the reflector, I have several pieces of steel roofing that I plan on using to lay under this radiating element.
Supports will be 2 sections of fence top rail with pully’s on far supports and paint cans as a counter balance.
12/22/2025 – starting to build out this antenna using 3D printed designs and some left over wire. 265 wire spreaders are needed and being printed as of writing this. First print I had ran off 150 separators followed by another 150. at 6″ apart this should be more than enough.
Here are some calculations for Length for 80 Meters
https://k7mem.com/Ant_Folded_Dipole.html
L = (299.8 × 0.5 × VF) / ƒMHz = 131′ 10″, (40.183 M)
What we are looking at is a ~132 antenna and my yard is NOT privy to that size antenna. I had to change my layout slightly to allow one leg to be bent at a 90 degree angle to allow this to fit on my property. Here is a bit more data on this antenna.
Output Data
D1 = #12 AWG, 0-5/64″” (2.05 mm)
D2 = #12 AWG, 0-5/64″” (2.05 mm)
Impedance Ratio = 4.000
Feed Impedance = 200 Ω
S = 0.63″ (15.88 mm)ft of length covert to inches.
we need every 6″ a spacer
1582″ / 6″ = ~265 spacers at .625″ widthlines cut to 131 11″
12/26/2025 – Antenna has been errected and performs nicely on 80 meters without having to cut it. I have considerable difficulty tuning on 40, but that is nature of this antenna. I have yet to try this on 20 Meters or every other band.
These metrics are running WSPR at 65W.
Here is 80 Meters at 20:00 EST
Here is 40M during daytime 14:00 ET.
kd2kub.org 