Can I connect wifi without Coax cable?
A coax cable is required to connect your modem/gateway to the Comcast network. The modem/gateway or a connected router provides a WiFi signal locally for you. Your WiFi devices may also receive other WiFi signals from other gateways/routers which you might be able to connect to without your own modem/gateway/router, in which case, no coax cable is required.
Presumably you are asking how to hook up a home wifi setup. But one way to connect to wifi without using a coax cable is to just connect to xfinity or XFINITY hotspot - they are ubiquitous and there may be one within range of you in case you really really don't like coax cables (like my cat).