so ive been putting off building my own dipole for like two years now because i kept telling myself id just buy something eventually. finally broke down and built a simple 40m dipole out of some 14 gauge stranded wire i had in the garage. used the standard 468/f formula and cut each leg to about 33.3 feet. fed it with 50 ohm coax through a SO-239 i salvaged off an old HF rig that died.

hung it in an inverted-V config off my chimney at maybe 25 feet at the center, legs drooping down to about 8 feet at the ends. when i swept it with my antenna analyzer the resonant point came in around 6.9 MHz instead of the 7.150 i was aiming for. SWR at 7.150 is sitting around 2.1:1 which my tuner handles fine but i kinda want to understand WHY its off before i just trim and forget it.

is the inverted-V configuration affecting the resonant frequency? i read somewhere that the drooping legs can lower resonance compared to a flat top. or is it the wire type, like stranded vs solid? also the ends are pretty close to some bushes, maybe 2 feet off the ground. could that be pulling it down that far? im not even sure what variable to start with here

yeah the inverted-V thing is real, drooping legs definitely lowers the resonant freq compared to a flat dipole. the rule of thumb ive always used is figure on needing to shorten by a few percent when you go from flat to inverted-V. but honestly 6.9 vs 7.15 is a bigger shift than id expect from geometry alone. the ends being that close to the ground and near vegetation is probably contributing a lot more than people give credit for. soil moisture, leaves, all that stuff loads the antenna electrically. id try raising the ends up off the bushes as much as you can first, even a foot or two makes a difference, then re-sweep before you start trimming. trim conservatively, like an inch at a time, you can always take more off but you cant put it back.

also 2.1:1 at your target freq isnt terrible honestly, a lot of guys would just run it with a tuner and call it done, but i get wanting to understand it first.

stranded wire runs a bit longer electrically than solid from what ive read, so that might be nudging things too. not a huge effect but stacks up with everything else you got going on. im dealing with something similar on a 20m dipole i threw up last month, mine resonates like 400kHz low and i still havent figured out if its the wire or the fact that half of it runs along the roofline of the house