so i finally got around to building a proper dipole instead of using that old vertical i borrowed from my buddy. used 14 gauge stranded copper wire i had lying around, cut each leg to roughly 16.5 feet for 40m, fed it with some RG-8X i had leftover. center insulator is just a piece of PVC i drilled holes through and used some stainless hardware from the hardware store, nothing fancy.

here's the thing though — SWR at the low end of the band like around 7.0 MHz is sitting around 1.4:1 which honestly i expected to be worse given my first attempt. but when i go up to 7.3 MHz it climbs to like 2.8:1 and my radio starts complaining a little. i thought dipoles were supposed to be relatively flat across 40m? the antenna is only up about 25 feet at the apex, kind of an inverted V shape because i dont have two trees far enough apart. both legs slope down to about 8 feet at the ends.

is this a length issue or is the inverted V shape doing something weird to the bandwidth? i checked my coax connections twice and they seem solid. using a Yaesu FT-891 if that matters at all. would trimming the legs help or would that just shift everything and make the low end worse?

yeah the inverted V geometry definitely affects the feedpoint impedance compared to a flat top dipole, the legs being angled down compresses the radiation resistance a bit which tends to narrow the SWR bandwidth. 40m is a fairly wide band so even a well-cut flat dipole can show that kind of swing across the whole 300 kHz. your 1.4 at the bottom tells me the antenna is resonating somewhere around 7.0 or maybe slightly below — if you actually want it centered more like 7.15 you might try trimming just a little off each leg, like 2-3 inches at a time and keep checking. trimming brings resonance up. i wouldnt worry too much about 2.8:1 on the high end honestly, the 891 should handle it fine with its internal tuner and if youre mostly doing SSB in the phone portion youre probably fine as-is.

i had almost the exact same thing happen with my first homebrew inverted V, ended up just using an LDG tuner between the radio and feedline and called it a day. not the most elegant solution but it works and i stopped obsessing over the numbers lol. what height are your end supports at? mine were dragging pretty low at first and i think that was absorbing some signal too