One portable field encoder that looks like a powerful way to deliver a live broadcast is the Live U Solo. The live U has options to interface directly with Facebook Live as well as a number of other destinations. It supports a number of different connection protocols, including ethernet, wifi, and has two slots for 3G/4G cellular modems. Any of these signals can be bonded together so you essentially get an aggregate of all the connections the device can manage, capping at a bit rate of 5.5Mbps. This makes the Live U ideal for any situation in which you would otherwise be relying on a single connection point you were worried might not operate reliably on its own.
An option with SDI retails for about $1500.00, and there is an HDMI only version for $995.00.