I am new to CCTVs/Security Cameras in general so please bear with me …I’m trying to replace 2 wired analog security cameras at my aunt’s commercial property due to loss of video connection. The system is 8-10 years old, part of a Lorex L19LD800 8-camera dvr system. At this point, she prefers not to replace the dvr unless absolutely necessary. I suspect the BNC line has an interruption at some point but because the line is several hundred feet long and is routed through a warehouse up about 20-30 feet in the air along I-beams, I think it would be easier to replace them with 2 wireless cameras instead. The problem is that there is a building in the way which is an obstacle between the camera position of one of the two planned wireless cameras and the office where the dvr is located. The other wireless camera has line-of-sight to the office dvr. 

From hours of Googling, I have seen discussions which seem to suggest that it is possible to set up a relay or repeater, which could route the signal around the corner of the obstacle building. I’ve included a diagram below to hopefully clarify the situation. I have no idea what such a repeater might be and would appreciate any advice or help in finding an appropriate device. I’m aware of wifi repeaters, of course, but since this is not wifi, don’t know what to even look for. I’ve seem a few during my web search that looked like they might be what I’m looking for:

http://www.securitycamera2000......eater.html

Here are the specs:

Wireless cameras: Revo RCWBS30-1BNC 2.4 GHz with added TP-Link TL-ANT2408CL 8dBi Omni-directional Antenna

Antennas on office building for dvr receiver: TRENDnet TEW-AO08O 8dBi Outdoor Omni Directional Antenna

Thank you in advance for your help!