so ive been putting this off for way too long but last weekend i finally just went ahead and built a simple half wave dipole for 40m out of some 14 gauge stranded copper wire i had in the garage. cut each leg to about 33.5 feet based on the 468/f formula, used a SO-239 chassis connector as the center feedpoint mounted in an old PVC junction box, and ran some RG-8X down to the shack. the whole thing is in kind of an inverted-V config with the apex at maybe 25 feet off the ground tied to a tree and the ends staked pretty low, like 4 feet on one side and maybe 6 on the other because of the yard slope.

anyway the swr at 7.150 is reading around 1.8:1 which i guess isnt horrible but i expected it to be closer to 1.5 or better given i followed the formula pretty carefully. also its resonant point seems to be down around 6.9 something, lower than i wanted. my question is do i just trim the legs or is the inverted-V shape messing with the resonant frequency and making it act longer than it should. ive read conflicting stuff about this. also one leg is running more or less over a chain link fence for about 10 feet and im wondering if that could be part of the issue or if im overthinking it.

yeah the inverted-V thing is definitely real, the closer those ends get to the ground the more the antenna electrically lengthens itself so your resonant point dropping toward 6.9 makes total sense. the formula gives you a good starting point but for an inverted-V with low ends you usually end up needing to trim a bit more than you'd expect. i'd try taking 3 or 4 inches off each leg and remeasure, do it in small steps. dont just cut a foot off and wonder why you went past resonance.

the chain link fence is probably contributing some capacitive loading too which could be pushing it further down. if you can route that leg away from the fence even a little it might clean things up. honestly 1.8 at 7.150 isnt bad and most tuners will handle that no problem but if you want it cleaner its just a trimming exercise. resonance and low swr arent always exactly the same point either depending on your feedline situation so worth checking where the actual minimum swr dip is across the band first before you start cutting.

the fence thing would bug me personally. ive had chain link just completely mess up a low dipole before, like changed the pattern in ways i never fully figured out. moved the antenna and everything improved. might be worth ruling that out before you spend a lot of time trimming.