fullsquare

there's a couple of amusing hells inside that job, you either have to deal with construction crews and contractors, jump between power poles including in cold and rain, wrangle with paperwork for permits for new lines, or fix horrors left by someone before you, it can be also dirty and people-facing

i still think that lots of people damaged by chatbots will stop in their tracks when this vc money burning charade ends, they won't be able to set up it all locally because chatbots brainrotted them even if it was possible in the first place

If you don't care about precise size, balls can be made cheaply by dropping drops of metal down tower where they are cooled by air as they fall, and then by water after they solidify. Then just sort by size

Ferrite beads allow you to use old calibration. If you make 1:1 balun just by threading coax through toroid, you can use old calibration as well provided it's the same coax. Keep in mind minimum bending radius of coax. There are other designs, like using twisted pair on toroid, then you have to include balun in calibration as well (it adds some electrical lenght). If you noticed changes after making air core, this suggests that you do have some common mode current, this will make your measurements sensitive to random changes as rf current flows on the outside of cable where it shouldn't

I've seen people using PE-Al-PE pipe for variables, this gives you layer of good dielectric (polyethylene) (but not as good as air) in dimensionally stable form. One connection is aluminum layer inside the pipe, and for the other you'll have to figure it out on your own. Retuning might be required anyway within the band (magloops are narrowband) Common way to make variables is to bolt two of them in series, so that no sliding contact is used, moving part is the same for both. This is good for high voltages also but i'm not sure if you'll need it

they do that anyway, there's a lot of ground. balls have lowest drag per mass for randomly oriented tumbling object

you can just pour balls in but any other shape has to be arranged one by one

~~Yeah this lower one looks better but still probably your capacitor value in loop is way off, try to find frequency where impedance is real (purely resistive; green line on smith chart crosses horizontal line in the middle) and work from there, then you'll know whether to increase or decrease it.~~ what LH0ezVT said makes more way sense than that, i forgot how magloops work. but you still might want variable capacitor

resonance is narrow so you might miss it. there's a reason why magloops are made with variable capacitors (sometimes retuning is required due to changes in ex. humidity)

how have you made your capacitor anyway?

you can put some ferrite beads on your coax close to feedpoint in order to eliminate common mode currents. better yet, use a balun. this might help you in getting more reproductible results

e: note how swr gets much higher when off resonance with properly calibrated nanovna. when measuring antenna with cable, you're seeing loss in cable as a degree of lowered swr but only with high swr, because energy is lost in cable when it bounces around and never goes back to nanovna

i'll add that in a way SWR chart is more resistant to misuse, because if nanovna is calibrated with wrong length of 50 ohm feedline, or without feedline at all, then smith chart will be rotated by angle depending on difference in length of that feedline, while SWR chart should look the same. for example, if real part of impedance at resonance is too low (ex. 20 ohm), and feedline is quarter wavelength different from what nanovna was calibrated with, then impedance will be still real but too high (ex. 125 ohm), while SWR chart should look the same (1:2.5 SWR minimum) (barring losses in feedline). (this works the same way as quarterwave long feedline impedance matching scheme). for different feedline length differences (non-multiple quarterwave) impedance will be complex at antenna resonance. this problem is avoided by calibrating nanovna with feedline

idk how you have done that, maybe i have older version but for me this marker just reads CH0 SWR 1.00/(value), this is some random vhf/uhf dipole that i found

you can pull up a smith chart, this will tell you whether impedance is too low or too high, since it's still not matched at resonance. if matched it'll be much milder for your transmitter but make sure that nanovna is calibrated (with feedline)

you can get away with very inefficient antennas on HF reception, so i wouldn't take SDR reading very seriously. (atmospheric noise dominates all noise, so amplification will get you useful signal with amplifier not introducing significant noise on its own. reverse is true on vhf, and especially on uhf and up)

resonance should happen no matter what power level. do you mean SWR 50 or 50 ohm? i'm not even sure if nanovna can measure SWR that high. it sounds like you have a short or open somewhere it shouldn't be? you need to calibrate it after changing tested frequency range, have you done that? (calibration can be saved). at the vhf-ish frequencies, it would make sense that your loop becomes full wave or even larger. circular loop has impedance of some 100 ohms, but you have capacitor at the ends of it so it's gonna be different

with magloops, with set size of loop, tune is via changing capacitance, match is via changing position (closer or further from loop, tilt away from plane of loop), shape or size (cross sectional area) of feed loop, you can match it exactly this way. coax stub can be lossy, if it's just 4W then probably not a problem but with higher powers check if it's not overheating

They could state it's Saudi right in the title

you're on lemmy which means you're around non-idiots a bit more often than usual. normal people don't use adblocks and treat chatbots like literal magic, you have to lower your expectations