Does the EDGE mobile network function independently of an antenna?

I have an old iPhone 4 with a faulty antenna. The WiFi doesn’t work and neither does the 3G network, despite the fact that I have plenty of mobile data, but EDGE still seems to work – the icon shows at the top when mobile data is enabled, and it loads websites load about as fast as can be expected of it.

Does this mean that EDGE functions independently of an antenna? If so, how exactly does it function?