so i finally got around to building a proper dipole for 40 meters instead of just running my random wire forever. cut both legs to about 33 feet based on the 468/f formula, soldered up a SO-239 at the center with some 14 gauge stranded i had in the garage. got it up in an inverted-V config, apex at maybe 25 feet which i know isnt ideal but its what i have.

thing is the SWR is reading like 1.4:1 around 7.150 but then climbs pretty fast toward the high end of the band, like 2.8:1 by 7.250 or so. low end of the band is fine, like almost flat. i was expecting it to be a bit off center but it almost feels like one leg is longer than the other even though i measured both. feeding it with about 50 feet of RG-8X into the shack.

should i just trim a few inches off each leg and see where it lands, or is the coax doing something weird here? i dont have a antenna analyzer, just the built-in SWR meter on my 7300 which i know isnt the most accurate thing in the world.

the inverted-V geometry does shift the resonant point a bit compared to a flat dipole, usually pulls it down in frequency a little. 25 feet apex is workable but yeah the angle of the legs affects the feedpoint impedance too, you might not be seeing a true 50 ohm match even at resonance which would explain why the curve looks lopsided. i wouldnt go trimming yet until you know where actual resonance is sitting.

if you can borrow a nanoVNA from someone in your club even for an afternoon it would tell you a lot more than the 7300 meter will. that said, 1.4 to 1 at your target frequency is honestly fine, most rigs and tuners handle that easy. the climb toward 7.250 is expected with a dipole that narrow, 40m is a pretty wide band for a simple dipole to cover flat. might just be the antenna doing what dipoles do.

i had the same thing happen with mine and it turned out one of my solder joints at the center insulator was intermittent, like it would read fine when i checked it on the bench but once it was up in the air and the coax was pulling on it at a slightly different angle it was making a bad connection. worth checking with a multimeter before you start trimming legs. also 14 gauge stranded is fine but make sure you got good strain relief at that center point or it'll work itself loose eventually.