this antenna is nothing special about gain, I think that is a similar like tactical 19 inch antennas.

You ask for the length of the cable, not the antenna. Unfortunately, I can’t find it listed anywhere. We can, however, “guesstimate” the length of the cable, using the length of the antenna, which we know is either 22 or 96cm. We will assume the antenna pictured, with the bundled cable beside it, is 96cm. The bundle of cable appears to be 2 thirds the length of the antenna or 64cm. It is hard to count how many loops of cable they have showing but the most loops I can count is 7 loops. Therefore 7 loops X 2 lengths per loop is 14 lengths. So, with each length guesstimated to be 64cm in length X 14 lengths of cable, equals (rounded off) 9.0m or 30ft, which sounds correct for mounting it on a car, especially if you mount it on the trunk lid and route it through the car. Mind you, the last antenna I bought had a 20ft or 6m cable on it. You can now guesstimate the length of the cable, for yourself, if the antenna pictured is the 22cm length. I hope this helps.

Dear, we haven't tried this project and can't help you. Perhaps you can consult on relevant professional forums.