What does the radiation pattern of such a microwave antenna look like on the board?

Question

WiFi

Dear radio operators, signalmen, graduates of radio departments, I greet you!
There is such a device Zyxel Keenetic 4G (home Wi-Fi router, model 2011). The device is quite old, but moderately smart and advanced, and most importantly: the software is updated and supports almost all high-speed LTE subscriber terminals of the latest models. Powered by 12V, you can buy for pennies, an excellent consumable for summer cottages with thunderstorms and poor power supply. It was produced in two editions: Revision A and Revision B. The latter is just different in that the external Wi-Fi whip antenna (2.4GHz, KU 5dbi) is supplemented with an internal one (in the photo below it is supposedly, but I'm not a specialist).

The diagonal of the white "silk-screen" rectangle around the copper is a little less than an inch. It is located in the most empty and farthest corner from the external whip antenna Wi-Fi 2.4GHz 5dbi. There is nothing special on the back of the board.

whole device assembly

The manufacturer said the following:

Added internal Wi-Fi antenna. Now the device uses both external and internal antennas (Diversity technology). The internal antenna does not increase the coverage area, but provides additional sensitivity, increases the reliability of communication when working with a wireless access point and is designed to deal with "dead zones" of reception.

As I understand it, the external whip antenna of the device has a diagram in the form of a spheroid flattened along the axis of the antenna (the gain of the antenna is only 5dBi, i.e. it is unlikely to be a pancake).
If the found rectangular structures on the board still have a second antenna, then I have three questions:
1) Where does it shine? "Dumbbells" perpendicular to the plane of the board? It would be logical to cover the half-sighted "poles" of the whip antenna, especially in a private house with three floors and a basement...
2) In what range are the KU of such antennas on the board usually? I'm guessing it's very small.
3) If you unscrew the external whip antenna at 5dBi and screw on the "whip" at 8-10dBi, will the electronics on the board not get sick from such mockery?
Another picture in the spoiler to understand the dimensions: below the Winbond chip on the right, you can see two rows of five patches with a pitch of 2.54mm (sorry for the electronic pun).
I understand that there is little practical use for this information, I rather broaden my horizons than coverage. Thanks in advance.

surrounding board (larger)

UPD: Guys, I appreciate the references on spatial diversity, MIMO and other things, but in these places my horizons are already expanded, do not waste time. Apparently, this is a weakly directional PIFA antenna, but what does its DN look like?

Answer 1

If the found rectangular structures on the board still have a second antenna

Of course, it's her.

1) Where does it shine? "Dumbbells" perpendicular to the plane of the board? It would be logical to cover the blind "poles" of the whip antenna, especially in a private house with three floors and a basement ...

Since its shape is not regular, but is a set of conductors of arbitrary length and width, it is hardly possible to accurately estimate its DN "by eye". I don't think any math can do it. Well, for starters, as a first approximation, consider it spherical. At the same time, it will fill the pauses of the pin at any inclination of the pin.

2) In what range are the KU of such antennas usually located on the board? I'm guessing it's very small.

You guess correctly. It is unlikely that there is even 5 dB there.

3) If you unscrew the external whip antenna at 5dBi and screw on the "whip" at 8-10dBi, will the electronics on the board not get sick from such mockery?

Absolutely not sick, I have done this more than once. It is only necessary to match the antenna with the 50 ohm cable as accurately as possible in order to prevent standing waves. Well, position the new pin in such a way as to make the most efficient use of its pancake-shaped DN, and in those directions where it has dips, rely on a weak built-in one.

Answer 2

as said, this is the second antenna for Diversity, it does not increase the coverage area. what is Diversity can be read in Google.
If you need to increase the coverage area, then you need to change the antenna.
electronics on the board will not be anything.

Answer 3

Looks like a ball. Perhaps slightly flattened in some direction (by 1-2 dB). Within the measurement error, it can be considered a ball.