Mystery flexible Antenna located on the screen assembly LG V20 H918
I noticed this flexible antenna (see pictures) mounted on the top of the screen assembly just above the grille of the earpiece on LG’s V20 H918 (T-Mobile) phone. Some screen assemblies come with it, some do not. There are two contacts that connect to two contacts on the main logic board. I own several V20’s, and I replaced the screen on one of them that did not have this antenna pre-mounted on the screen assembly. I tried heating up and moving the antenna from the broken screen to the new one, but it was so delicate and it tore. The phone still appears to work fine. Does anyone have any idea what this antenna is for? I did some testing using one phone with the antenna intact, and another without this mystery antenna. Here is what I have ruled out so far:
WiFi: Comparing two phones side by side in several different locations, there is no difference in WiFi signal levels on both 2.4GHz and 5GHz. They are always within 1 dB of each other.
Bluetooth: Bluetooth appears to be working properly, and pairs with anything just fine. I used the Nordic BLE scanner to look at the signal from a few BT Beacons I have, and just like WiFi, signal level on both phones is the same. Since Bluetooth is 2.4GHz, I would imagine that the same WiFi radio is used for both.
Cellular Radio: The only bands I am able to test are 2, 4, 12, and 66. By using the “secret menu” - (dial 277634#*#) I was able to activate one band at a time on both phones, confirm LTE service with the engineering sub-menu, both band and signal level. Again, both phones were the same.
GPS: Using the phone without the mystery antenna, while driving around Google Maps worked perfectly. I disabled all the options to use cell towers, WiFi, and other means to determine location. Having both phone side by side on the passenger seat, the map showing my current location was identical.
FM Radio: I tested the FM radio app (which only works when a set of wired headphones are attached) and both phones had the same reception signal to noise ratio (subjective.) I know the headphone wire acts as the FM radio antenna. The mystery antenna is physically too small to work on the relatively low 88MHz thru 108MHz band.
The NFC antenna is a coil located on the back cover of the phone around the camera lens assembly - so I rule that out - unless there is something I am overlooking.
There is also Android Beam, which I believe uses Bluetooth.
There are only four ideas that I have that this antenna could be used for and am hoping someone can confirm or dismiss:
(1) ANT+ - According to the Internet (which never lies or has fake news) the LG V20 does not support ANT+. However “ANT Setting” shows up in the secret menu and only has one item “Calibration Status.” I am not sure if ANT in this secret menu is for the ANT+ service commonly used for wearable health monitoring devices, or simply ANTenna?
(2) A cellphone band that the LG V20 H918 supports that is not documented, and is not used with T-Mobile. Perhaps 850 MHz? I tried using an app called LTE Discovery, but that didn’t help.
(3) The screen used in the LG V20 series is a common part, and the H918 version I have does not use that antenna at all. However, there are in fact two contacts on the logic board that connect to it.
(4) Super secret (not so much a secret, really) transmitter that tells the government what I am doing at all times. LOL
Does anyone have any ideas? Thanks in advance.
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