What's the difference between these antennas?

[Thermoelectric]

Hey all,

Bit of background, these antennas are for LoRaWAN hotspots (specifically Helium) and there's a lot of noise about some antennas being better than others. I bought a couple of each and haven't seen massive differences in performance, however the antennas seem reasonably physically different to eachother. I tried delving into researching antenna design to make sense of it and it seems like quite the rabbit hole.



The grey one is a 6dBi "tuned" 915MHz antenna VSWR 1.02 (this is the "better" antenna), the white one is 5.8dBi 915MHz VSWR 1.13.

Given they're about the same gain, why does one have more "sections" than the other? A friend suggested this could be due to one being half wave vs full wave etc. but that's well over my head and wasn't overly apparent from information I could find online.

Here are some other cheapies from Aliexpress, same design but also with differing numbers of segments



My guess is they're some weird collinear design, like figure 3 here. This also seems to be some RF voodoo



Thanks for any help!

edit: seems I can't make the inline attachments work but you get the idea

[cdev]

The bottom antenna appears to be missing its top.

These are collinear antennas. You found the patent which explains how they work. You can make them yourself, easily, and they work, well, for UHF, but it makes sense to measure the exact velocity factor of that specific batch/kind of coax.