unless you buy all your antenna from dealers you will need some way to check your antenna
a cheap and useful bit of kit is a NanoVNA the older 2.8″ display version (SMA ports on short side) is available for under £30 on ebay or £40-50 on amazon, the newer v2 version with a larger 4.3″ display (SMA ports on long side) for under £50 on ebay or about £80 on amazon
just put NanoVNA in the search of your favourite shopping site to find one
its a little piece of kit with an internal battery so useful in the field or in the shack
it can be used stand alone at your antenna feed point (but the menu system can be confusing) or with a program on a computer and the rig end of your coax
the NanoVNASaver program is downloaded from https://github.com/NanoVNA-Saver/nanovna-saver/releases there are releases for linux, windows and mac
it unit needs calibrating before each use see https://www.youtube.com/results?search_query=nanovna+calibration , calibrate it for the range you want to check, as it has a max 101 calibration points, so the tighter the band the more accurate the calibration
if calibrating for HF set the frequency limits 1 – 50mhz
if calibrating for VHF / 2m set the frequency range for 120-180mhz
if calibrating for UHF / 70cm set the frequency range to 350-500mhz
you get the idea
once calibrated you can then check your antenna, see https://www.youtube.com/results?search_query=nanovna+swr+test
the beauty is you can see where the antenna is resonant if it is low, shorten it, if it is high lengthen it
these little toys can not only be used for SWR, but also cable length, filter response curves (low pass, high pass and band pass) and much more, plenty of how to video’s on youtube to explore
enjoy and have fun