Wireless access point with multiple user groups

I have seen this function before on a router, it was called Guess something, like guess pass or something. I was awhile ago, so i don't remember, i think it was a cheep Blink router my friend bought at target or something
But you can do this with another way. You will need two routers with wireless capabilities.
I am not sure how your network is setup. I am assuming a standard house hold where it is internet router of some sort, then your internal network.
Ok first router 1 this is going to be your "public" network router, your are going to plug your internet in to this one WAN port, and then plug router 2 WAN ports in to one of routers 1 normal ports. Then add security or what every so only the people/devices your want to have access to router 2's wireless. and plug the rest of the network in to router 2.
Router 2 will see router 1 and what ever is connected to it as the internet. and keep it blocked from the rest of the network.
I am sure there is a lot better solution for this, but i am not that good with networking yet.  .
I know there are virtual networks, and based on your MAC address puts you on to what network your belong, that might work to.

Thank you for the reply, but I am constructing this network for a small business with multiple buildings. Some of the buildings need to have public and private network access, and I am trying to avoid using multiple access points or routers at every building.

Thank you, that helps.

Best answer selected by Wafip.

i know you've already found one answer, but i thought you should know that the pepwave officepoint can do the same, for much less than the aironet.

(note: i am a marketing consultant for pepwave & peplink)