S400 is the same as LMR400. It uses the same connectors and such. Loss in the coax is 2.4 Ghz - 22.5db/100m 5.8 Ghz - 35.5db/100m as you can see there is a 50% increase in loss between 2.4 and 5.8 Ghz. You also need to remember that this loss is bi-directional so you have the same loss on the transm...