so i finally got tired of paying stupid money for commercial antennas and decided to just build a 40m dipole from scratch. used 14 gauge stranded copper wire i had lying around from some old electrical work, nothing fancy. cut each leg to about 33.5 feet based on the 468/f formula and threw it up in an inverted V configuration off my 35 foot mast with the ends tied off to some trees maybe 10 feet off the ground.

tuned up with my antenna analyzer and got like 1.8:1 SWR at 7.150 which honestly surprised me, i was expecting to have to trim a bunch. did a few contacts and signals seemed fine, got a 59 from a station in ohio on 100 watts which i mean maybe that doesnt tell me much but still.

my question is kind of dumb but — is that SWR just luck or is the formula actually that reliable for a first cut? i feel like i must have done something wrong because it was too easy. also wondering if the inverted V shape is hurting me compared to a flat top, the ends are definitely drooping quite a bit.

youre not lucky, the formula just works pretty well especially on 40 where the wire length is long enough that small errors in cutting dont throw things off as badly as they would on say 10m or 6m. the 468 constant already accounts for the velocity factor of bare copper wire in free space and most people end up within trimming distance on the first cut. that said your environment matters too — being close to trees and having the ends low like that can actually load the antenna a bit and pull the resonant point down slightly, which in your case probably helped if anything.

inverted V vs flat top is a real tradeoff but honestly for general HF use the inverted V is totally fine. you lose a little off the ends in terms of radiation angle and the feedpoint impedance drops a bit from the classic 72 ohm flat top value, more like 50-60 ohms depending on the angle, which actually makes it match coax better without a balun in some cases. the main thing you lose is some low angle radiation which matters more for DX than for domestic contacts. for 40m ragchewing and general use youre good.

yeah the formula is legit, ive built probably a dozen dipoles over the years and i almost always end up trimming less than a foot off each side at most. the bigger variable is honestly what the wire is near — buildings, gutters, wet ground right under the feed point, all that stuff shifts things around more than the cut length does in my experience. your inverted V is fine dont overthink it, mine has been up for three years in basically the same config and works great for everything except serious DX chasing where id want something with lower takeoff angle anyway.