One big AP to cover whole place, possible ?

RouterOS Wireless Networking
1

Is it possible to use one big AP + Antennas to cover 1km square ?
Client devices will be Smart Phone or Laptop.

2

Absolutely. Especially if there are no buildings, no interference (say other wifi radios or devices), and a certain amount of users appropriate to the hardware you are selecting. If you scroll down a bit I started a discussion on the 435Gs that might help answer some of the questions I think you’re thinking of…the follow up to this one is what antennas, what hardware.

-Mac

3

Normal device like smart phone or laptop are able to transmit back to the AP ?

4

phones can only transmit some 100 meters. there is no way to achieve this for phones.