Hi, I am in the Real Estate business and have been looking into Part 15 transmitters to help with Sales. We all know how the market is right now. After extensive research I have ruled out FM, the limited range (200ft) Just didn’t seem enough. I then went to a radio engineer to help me with my search, legality questions and my search of which system would work best for me. Glad I did! He had said that some of the systems I had been looking at in his opinion would be illegal to operate. It seems that the systems with the roof mount antennas in which the transmitter is in the house weren’t legal because Part 15 limits the connection between the antenna and the transmitter to 3 meters, including the antenna length. It was his opinion that these transmitters weren’t certified with these remote antennas and that Part 15.203 makes using any antenna except the one the transmitter was certified with illegal. I am asking your opinion as to if this is all true and if this product is widely used as it appears how can all this be? If this system is used in this manner it is illegal to use?