USB device to act as a wifi transmitter?

I have a wired computer in my shop.
I bought a Republic Wireless cell phone.
This cell phone is supposed to connect to the WIFI network at home and use VOIP and data for all its communication. It does but when I go out to my shop the WIFI connection is too weak. I bought a regenerator (they called it an extender) and that shows up as strong out in my shop but my phone won't connect to that signal.
I think my phone will only connect to one WIFI outlet at once. Is it possible that because I don't have a password on the regenerator that I cannot connect. If putting the same password on the regenerator as is on the WIFI network will fix the problem than I am good

However

If that won't work. Is there a device I can put in a USB port on my shop computer that will transmit a WIFI signal?
Can I get a splitter for my cable connection in my shop and then plug something into that?

What do I need to do to fix this?

Thanks for considering my problem.