If you're looking for a solution that enables POE and Data to run over a long length of coax cable then the Veracity VLS-1P-BC LONGSTAR Base and Remote Unit is worth consideration.
The typical application would be to run an IP Camera over a long cable run, however any data related product can be connected where a 100mbps connection is suitable.
Normal CAT5E/CAT6 cable is only suitable for 100 Metres, especially when being used with POE, some of this is due to the thin gauge of the wires inside the data cable.
Depending on the coax cable used, 200mbps is possible at 1.4km (Using RG11 Cable) however this distance is reduced when using lower grade cable, i.e. 690 metres for RG59 Cable.
75ohm is recommended, however 50ohm can be used as well.
Above, you can see that the POE Range is reduced when the power requirements of the camera or POE Device increase, and to achieve long distance you need to use Veracity's only Power Supply Unit.