Good antenna for 2.4 GHz (Zigbee, Bluetooth)

[raven karma]

Hi all!

I've been diagnosing why my Zigbee coordinator has such a poor signal while my (Zigbee) routers are fine. And then I tested the antenna using a VNA. I found out that pretty much all those 2.4 GHz antennas you can get for 2 EUR are useless as the VSWR is never under 5 (or even 10) at 2.4 GHz. And both of the antennas I got from AliExpress that claim to be "2.4 GHz Zigbee antenna" are even worse. Most of the antennas that come with ESP32 modules have similar issues.

The funny thing is that antennas from my old wifi AP are also pretty bad. But Liligo's LoRa antennas are amazing for 868 MHz. I also found one good antenna in between all those I got for my ESP modules but I have no clue where that came from.

Anyway, can anyone please recommend a good omnidirectional antenna for 2.4 GHz? Preferably from AliExpress or somewhere in the EU.

PS: Yes, the coordinator is on a shielded USB 2.0 extension cable.

[rigid skiff]

a higher gain antenna is not normally a benefit with zigbee. it's a very low power protocol, and having one device broadcast at higher power than others can sometimes cause more interference. Are you having any actual problems or are you just complaining that "number is low"?

if your zigbee coordinator is near your wifi access point, double check your zigbee vs. wifi channels for possible interference.

[raven karma]

I am very much complaining that "number is high" (not low). And I'm talking about VSWR (how well the antenna is tuned), not gain. Cheap antennas suck. They resonate everywhere except at the frequency I want them to.

The coordinator is nowhere near any 2.4 GHz transciever.

I just want a tip for a good antenna. That's all. My coordinator did not come with one and, as I said, every antenna I tried sucked.

Also, yes. As I said, I am experiencing problems. To elaborate: RSSI of devices connected to the coordinator is way lower than of those connected to any of the routers. And devices in direct line of sight about five meters away keep dropping out if they're connected directly to the coordinator.

[rigid skiff]

very strange that you didn't get an antenna with the coordinator; which one did you get? fwiw, the home assistant ZBT-1 and most zigbee devices use PCB antennas rather than external antennas.

it's unlikely that you'll run into anyone here who is using a zigbee coordinator with a replacement antenna and has the radio experience to evaluate it objectively... but you never know, maybe there is someone :/