Added about a 1' chunk to the 80m segment of the 80/40/20 fan dipole. Below is a comparison of the antenna before and after the addition. Not allot of change , especially with the 80m band. Next up adding a few feet to the 80m segment!
VSWR VSWR After 1' added to VSWR After 5' added to 80m
Original 80m segment segment 2" removed 20m
80m
Freq
3.7 3:1 3:1 3:1
3.75 1.5:1 1.5:1 1.5:1
3.8 1:1 1:1 1:1
3.85 1.5:1 1.6:1 1.5:1
3.9 2.5:1 2.3:1 2.2:1
40m
Freq
7.0 1.2:1 1.3:1 same
7.05 1.2:1 1.3:1
7.1 1.5:1 1.6:1
7.15 1.6:1 1.9:1
7.2 1.9:1 2.2:1
20m
Freq
14.0 2.2:1 3.1:1 >3 wont tune
14.05 1.7:1 2.3:1 3.2:1
14.1 1.2:1 1.6:1 2.1:1
14.15 1.2:1 1.6:1 1:1
14.2 1.6:1 2.1:1 2.3:1
Just had to sweep it with the Nano VNA
500 kHz to 60 mHz
80m
40m
20m
Sure looks like the 40m segment is a wee bit long. 80m is sure narrow band would really prefer it closer to 3.5 MHz 20m is anyones guess. The IFL is 500' long and because of this I get allot of standing waves created on the IFL which makes it a little difficult to judge resonance. One way of "tuning " the antenna is to add or remove IFL....doesn't make it resonant just makes it load better.
Ultimate goal is to get the desired freq under 2:1 VSWR keeping in mind a 2:1 VSWR equates to a 1 db loss in TX Power.
So the plans is ....#1 lengthen the 80 segment then test again #2 depending on the results after lengthening the 80m segment I may want to shorten the 40m a bit. #3 look at 20m after wrapping up the first two steps.
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