so ive been putting off building my own antenna for about two years now because i kept telling myself id mess it up and just buy something. finally bit the bullet last weekend and built a simple half wave dipole for 40m. used 14 gauge stranded copper wire i had lying around from an old extension cord project, cut each leg to about 33.5 feet based on the 468/f formula, fed it with some RG-8X i had leftover, and threw it up in an inverted-V config between two trees maybe 25 feet at the apex.

problem is my SWR at 7.200 is sitting around 2.8:1 which is higher than i expected. at 7.100 its closer to 2.1 which is more usable but still not where i want it. i trimmed the ends once already and it got a little better but not dramatically. im using a Yaesu FT-891 and its internal tuner can handle it but i dont really want to rely on the tuner if the antenna itself is the problem. anyone have thoughts on what could be throwing it off? i double-checked the center connection and it looks clean to me.

the stranded copper from extension cords is fine electrically, dont let anyone tell you otherwise. but 25 feet apex in inverted-V is probably compressing the radiation angle and also slightly shortening the electrical length compared to a flat dipole — the inverted-V legs being angled down like that actually means the antenna acts a bit shorter than it measures. try adding maybe 6 inches to each leg before you do anything else and see if the dip shifts down toward where you want it.

also — and this might sound dumb but ive been burned by it — are you sure your feedline isnt picking up RF? stranded wire at the feedpoint with no choke balun can cause the coax braid to become part of the antenna and that'll mess with your SWR readings in weird ways. a couple ferrite beads or a simple 1:1 choke wound on a toroid right at the feedpoint fixes that and sometimes completely changes the SWR picture. worth ruling out before you keep trimming.

yeah 2.8 on 40 with a homebrew first attempt honestly isnt that bad lol. my first dipole was like 4.5:1 because i didnt account for velocity factor on the coax when i was doing some calculation i half understood. anyway the choke balun thing the other guy mentioned is real, i thought it was kind of voodoo at first but it genuinely made a difference on mine. also what does the SWR curve look like across the whole band? if its a clean curve thats dipping somewhere predictable you just need to trim or extend, if its weird and lumpy theres probably something else going on with common mode current or a connection issue.