05-08-2024, 09:40 PM
Colin
There doesn't appear to be much antenna height above the shed roof - or is that an optical illusion ? Close proximity is not going to help your cause.
Secondly, the image of the nanoVNA is too low in resolution for me to see the scales so the frequency and SWR plot (assumed) simply doesn't present useful info. Is it feasible to grab a better image of the nanoVNA screen and re-submit ?
Don't forget that the stainless scourers in the 50mm PVC pipe will also keep out snakes if you stuff the pipe such that they can't push it through/out.
My recollection of a multi-band G5RV-like antenna I used at one time was that there were lots of resonances across HF, and your VNA display doesn't show that. How confident are you that your BALUN is the correct Z-ratio ? (my memory says that I used a 4:1 but this was some 20 years ago so that might be in error..) Similar resonance responses happened when I tried an OCF dipole for multiband use too, still a 4:1 BALUN. Yours is lacking that effect and the only thing obvious to me is that the impedance transformation ratio could be a long way from optimum.
My multiband wire antennas these days are 'ray dipole' sets, one for 1.8/3.5/7/10/14 MHz and a second one at near right-angles for 3.5/7/10. [ yes, I can fit a full size 160M dipole in my yard..] Somewhat tedious to tune in the beginning but easy-ish once you get the process sorted, and then provides good results without significant tuning interaction. I used 3mm stainless steel stranded wire (7x7) in lieu of copper so that I would forever lose the moving-frequency effect through wire-stretch. Set up probably 8 years ago now and never needed to re-adjust dipole lengths...
I know stainless is not recommended by the antenna-bible-bashers (due skin resistance losses at RF) but it is still a good enough option for mechanical reasons.
Keep up the reports Colin, it's always interesting to see how others fare with their antenna experiments/installs.
Doug
There doesn't appear to be much antenna height above the shed roof - or is that an optical illusion ? Close proximity is not going to help your cause.
Secondly, the image of the nanoVNA is too low in resolution for me to see the scales so the frequency and SWR plot (assumed) simply doesn't present useful info. Is it feasible to grab a better image of the nanoVNA screen and re-submit ?
Don't forget that the stainless scourers in the 50mm PVC pipe will also keep out snakes if you stuff the pipe such that they can't push it through/out.
My recollection of a multi-band G5RV-like antenna I used at one time was that there were lots of resonances across HF, and your VNA display doesn't show that. How confident are you that your BALUN is the correct Z-ratio ? (my memory says that I used a 4:1 but this was some 20 years ago so that might be in error..) Similar resonance responses happened when I tried an OCF dipole for multiband use too, still a 4:1 BALUN. Yours is lacking that effect and the only thing obvious to me is that the impedance transformation ratio could be a long way from optimum.
My multiband wire antennas these days are 'ray dipole' sets, one for 1.8/3.5/7/10/14 MHz and a second one at near right-angles for 3.5/7/10. [ yes, I can fit a full size 160M dipole in my yard..] Somewhat tedious to tune in the beginning but easy-ish once you get the process sorted, and then provides good results without significant tuning interaction. I used 3mm stainless steel stranded wire (7x7) in lieu of copper so that I would forever lose the moving-frequency effect through wire-stretch. Set up probably 8 years ago now and never needed to re-adjust dipole lengths...
I know stainless is not recommended by the antenna-bible-bashers (due skin resistance losses at RF) but it is still a good enough option for mechanical reasons.
Keep up the reports Colin, it's always interesting to see how others fare with their antenna experiments/installs.
Doug
Doug VK4ADC @ QG62LG51
http://www.vk4adc.com
This Forum is only going to be as interesting as the posts it contains.
If you have a comment or question, post it as it may trigger or answer the query in someone else's mind.
http://www.vk4adc.com
This Forum is only going to be as interesting as the posts it contains.
If you have a comment or question, post it as it may trigger or answer the query in someone else's mind.