Your not being rude question away until you understand I dont mind.
Antenna diversity or to be more correct in RF terms spacial diversity is used to combat the effects of mutil path loss.
Multi path loss is caused when a wave radiates out from a transmitter but some of the wave is reflected of an object, this reflected wave now also reaches the receiver.
As radio waves travel at very close to the speed of light ( doest matter at what speed as long as its a constant) and the 2 paths are of different lengths
Path one is direct
Path two is via the object we reflect of
This means that the waves will arrive at 2 different times.
Now think of 2 sine waves and of set one by 90degrees (the amount of time that it takes for that wave to travel half a wave length) If you look at these 2 sine waves you will see at some points in time the 2 waves areat their peak but in oposite and other times they are at their minimum. At the time they are at their peak but oposite the average vaule of these 2 waves is close to 0 they cancel each other out and at the other times they add together to make the average value bigger. If we hit 180 degress out of phase they will completly cancel each other at all points
Back to our radio waves, they have taken different times to get to the reciever so they are out of phase, this will mean that these waves may either add together or cancel each other out if you move the receiver over by a few inches then the results of adding and subtracting will be very different.
The 2 anttenna play of this fact that if one antenna is receiving 2 signals that are 180deg phase shifted then a few inches away the 2nd antenna will not be seeing these same 2 signals at 180 deg phase shift.
I hope from this you will see that you need 2 anntena for diversity.
If you have only 1 but configure diversity then it is of no harm as the port with no antenna should always be the lowest signal strength and blocked but this is not antenna diversity and you have no immunity to multi path loss.
