so i finally got around to building a center-fed dipole for 40m, been putting it off for months because i kept second guessing myself on the math. used the 468/f formula and cut my wire to around 66 feet total, split in the middle with a SO-239 chassis connector i had in the junk box. wire is just 14 gauge stranded from the hardware store, nothing fancy.

hung it up in an inverted-V configuration with the apex at about 35 feet off a fiberglass push-up mast and the ends drooping down tied off to fence posts maybe 8 feet up. fed it with about 50 feet of RG-8X into my 7300.

problem is my SWR at 7.200 is reading like 2.8:1 which i wasnt expecting. i trimmed a little off each side and got it down to about 2.3 but that still seems high. the radio is tuning it fine with the internal tuner but i kinda want to understand whats going on rather than just let the tuner handle it. is the inverted-V shape throwing off the resonant frequency or did i just cut it wrong? ive read that the angle of the legs affects things but i dont really know how much

yeah the inverted-V thing will definitely shift your resonant point compared to a flat dipole. the closer those legs get to being vertical the more it shifts, and with your ends only at 8 feet and apex at 35 that's a pretty steep angle. generally you want to add a few percent to your wire length to compensate, some people say up to 5% depending on how severe the droop is. also the ground beneath and whatever the wire is near (fences, your mast material, anything conductive) all loads the antenna and moves things around. 2.8:1 at 7.2 is actually not terrible for a first build honestly, means you're probably resonant somewhere just not right where you want it. id try adding a foot or so to each leg before trimming more, easier to cut than to splice back in. and check your connector too, a bad solder joint on a chassis SO-239 will mess with your readings

i had almost the exact same issue with my first 40m dipole, drove me nuts for a weekend. turned out one of my legs was like 4 inches longer than the other because i measured wrong off a spool that had kinks in it. once i actually straightened the wire out properly and remeasured i was way off on total length. might be worth double checking your physical measurements with the wire stretched straight before messing with the formula. also 14 gauge stranded from the hardware store is totally fine btw, thats basically what most people use