lusty glen
Here are some antennas Ive made. Image 1 , the one of the left is for 2.4ghz using coaxial cable while the one on the right is a 1/4 wave antenna for 925mhz with the antenna made from a thin copper rod. Image two larger antennas one being flattened 5mm copper pipe the other being stainless steel tube both are ideal for a wide range of frequencies including 2.4ghz, 5ghz and 6ghz; also a 5v amplifier and a power supply (diy). Image three assorted small antennas some for 2.4ghz some for 433hmz and surrounding subghz, also an esp32 that I've connected a 2.4ghz antenna to as well as a ebyte nrf24. Image 4 a lily go cc1101 tembed, a (very dodgy) diy meshtastic device (I'm too cheap to buy a standalone so i2c it is) and a flipper zero.
I get a bit disheartened looking at the quality of ipex to sma adaptors (which we are often limited to with microcontrollers). I think its worth the investment buying a roll of RG316 coaxial cable, sma and ipex bits and pieces, a crimping tool and we can't forgot the heat shrink.
Remember its the frequency ÷ the speed of light (how cool is that) to work out the size. Here is a handy calculator for simple dipole antenna.
https://www.onesdr.com/dipole-antenna-calculator/
If you've made an antenna post it, I'd love to see it!
fringe willow