Running dual antenna WiFi card with only one antenna?

Hello, I am wondering if I can do this.

I have read that running a WiFi card with no antenna can damage it.

I am wondering if that applies to this scenario as well.

I know I will lose bandwidth, I am only concerned about damaging the card.

Thank you

Wouldn’t know about H/W damage, but it’ll operate [VERY] poorly
Can always buy a set of individual antennae or a single cabled base

The firmware in the card is supposed to decide how to initialize the radio and the amplifier and whether to turn on and try using the secondary antenna or not.

Modern cards have electrical protections in place that are supposed to be prevent flaky antenna from burning out the amplifier…

(same way usbkill doesn’t kill usb ports of laptops… well at least on a macbook where they’re opto coupled, and same way POE doesn’t kill gigabit ethernet, because it’s mag coupled by spec… but reality and specs aren’t really the same in practice)

… but if the signal processors are trying hard to use the antenna that’s not there for mimo, and they see noise and weird reflections from e.g. the case or a nearby big piece of metal, I have no idea how that’ll behave… probably similar to just attaching one nice antenna and one very bad one.

Can I ask more about your use case?

Do you have a 2x2 mimo card, and are trying to steal your neighbors wifi with biquads and pringle can antennas?

… or are you after something else?

You know you can get relatively cheap, relatively high gain, point to point “antennas” . e.g. like these LiteBeam thingies that speak “airmax” instead of 802.11 for simpler bridging and more throughput (tdma instead of csma/cd).
There’s other’s that will talk plain 802.11 wifi as well – if you really want that over a long distance.

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That is a great reply. This is all about my laptop.

Some locations I visit have poor reception so I have to use a directional antenna.

I was thinking of modifying my thinkpad so that the internal WiFi card uses one of the thinkpad’s antennas and replace the second one with an external RP-SMA connector. That way I can just bolt on my APA-M25 when needed. I can’t have it always on because the laptop won’t fit in the bag and I don’t want to screw/unscrew an antenna every time.

I also have an Alfa awus036ACM I can use but that means that I have move the laptop around with a USB that can break (I am prone to breaking them) and also possibly having to modify my network config each time I am changing adapters (networkd + WPA_supplicant).