The ASRock Phantom Gaming PG34WQ15R3A has a 7 dBi Wi-Fi 4/5/6/6E/7 antenna integrated into the stand. The idea behind this feature, unique to several Phantom Gaming monitors as far as I'm aware, is to improve the wireless networking performance of your PC, especially if your case is located under the table, which greatly hinders both wireless signal reception and speed.
The implementation is straightforward: the stand has a pair of RP-SMA antenna connectors, and the monitor is supplied with a pair of extension cables, which you have to use to connect to your motherboard's RP-SMA plugs. You don't need to do anything else; your computer's Wi-Fi card will start using the monitor's 7 dBi antenna automatically.
To test the actual benefit of this feature, I used the OpenSpeedTest app, installed on my Synology NAS, to test the wireless network performance with several different antennas connected to the Wi-Fi card integrated on my test system's motherboard. The motherboard in question is the ASUS ROG Maximus Z690 Formula, which is a high-end motherboard equipped with the Intel AX210 Wi-Fi 6E module, and bundled with a capable 2T2R wireless antenna, which can be attached to any metal part of the case or even placed on the table, as its magnetic base doubles as a table stand.
It's also worth mentioning my house has an elaborate wireless network, built around a total of seven Asus Wi-Fi 6E mesh nodes, which ensure excellent Wi-Fi coverage in every corner of my home. I didn't want the Wi-Fi card to hop between mesh nodes for this test, looking for the optimal one, so I've bound my test system to a single mesh node. I picked the one that would best represent the usual wireless router placement in a typical home environment. The tests were done with the external Wi-Fi antenna supplied with the motherboard, a pair of regular Wi-Fi antennas taken from an old TP-Link Archer C9 router, and the 7 dBi antenna integrated into the monitor's stand. I did the tests both with the PC case placed on the table and under it.
The 7 dBi antenna integrated in the monitor's stand brings a substantial boost to the wireless performance, even when the motherboard is already bundled with a capable wireless antenna. Looking at the numbers, ASRock is on to something with this feature, and I'd love to see it on more monitors in the future.