so ive been meaning to do this for a while and finally just built a simple 40m dipole out of some 14 gauge stranded wire i had laying around in the garage. cut each leg to about 33.3 feet going by the 468/f formula, fed it with some RG-8X i had left over from a previous project. center insulator is just a piece of PVC i drilled holes through, nothing fancy.

here's the thing though - on 40m the SWR is sitting around 1.4:1 which honestly is fine, better than i expected for a first attempt. but when i tried it on 15m (which should be the 3rd harmonic right?) the SWR is like 4:1 and my tuner is struggling with it. i thought dipoles were supposed to play nice on odd harmonics. maybe my legs are slightly off? or is this just the nature of end effects and i need to trim a bit. the antenna is in a slight inverted V configuration, apex maybe 30 feet up tied to my chimney and the ends drooping down to about 10-12 feet off the ground. just wondering if anyone else has seen this on homebrewed dipoles before i start hacking at the wire.

yeah the inverted V configuration changes things a bit compared to a flat-top dipole, the drooping angle affects the resonant frequency and the harmonic behavior isnt always as clean. 4:1 on 15m isnt shocking honestly. a decent tuner should still be able to handle it though - what tuner are you running? some of the cheaper auto tuners give up around 3:1 or so and call it a day.

also 14 gauge stranded with any insulation on it means you probably need to trim a little anyway, insulated wire usually needs to be cut a bit shorter than bare copper for the same resonant frequency, something like a 2-3% reduction depending on the insulation. so your 40m resonance might not be exactly where you think it is and that would cascade to the harmonic being off too. id start by confirming the 40m resonant point with an antenna analyzer if you have access to one, then go from there.

built basically the same thing last spring. mine was only up about 25 feet at the apex and i had the same kind of issue on 15. ended up just using a tuner and calling it good, got it to match well enough for normal operation. honestly for a first homebrew antenna id say dont overthink the trimming, just throw a tuner at it and work some DX. you can always refine it later once you understand how the antenna behaves across a few weeks of use.