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40M X 80M NVIS Antenna for WFD event Jan 25th.

 

Hello David,

The 40M leg is too long.
The SWR and RL are rising with the increase in frequency.

The 80M leg is too short.
The SWR and RL are improving with the increase in frequency.

HTH...Bob VK2ZRE

On 20/01/2025 3:30 pm, David Gerhart wrote:
Hey,

I wired up a 118' X 68' crossed dipole antenna per the recipe here . I was able to get very good transmission 5x9 to a collaborator some miles away on 3.190MHz. The 40M leg seemed more difficult. So I hooked up my Nano VNA-H to the Feed Line. I set the calibration plane at the input to the VNA. The network is 75' of RG58 to a 1:1 Unun, then the Antenna.

NVA Sweep Results attached. I didn't fuss with markers, or other settings ...

What do the measurements suggest? I have some opinions, but thought to listen first.

My goal is to tune it up a bit for Winter Field Day...

Enjoy, and thanks in advance for any thoughts you share.
 

Yes the lengths are wrong but the DX Engineering one is even more off

John ve3ips

So 34 ft for 40 and 70 for 80m then tune for resonance
John ve3ips
 

thank you.

Interesting to find that my antenna tuner likes the 80m band better (not by a lot) than the 40.

What is interesting is how quiet they both are. NVIS being this close to the ground (an inverted v from 16' center.)

I made QSO's to day on 40m out to 400 miles.

I'll trim the 40. but the SWR min on the 80 lands in the middle of my license as a general. May not lengthen.

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