Dyne's LD-F1 (D-O concept) build

[kresty]

I wonder how a power car antenna does it?

I believe they have a spool that works somewhat like a measuring tape (i.e. flexible enough to coil, rigid enough to extend the antenna without collapsing when unspooled).  

My friend suggested something like that, but I don't think I have anything that'd work as the tape (except maybe filament, and even then it'd probably require the spool to have a large diameter or it'd break unless it's nylon).  It probably also relies on the tube having a large enough ID for said tape to run all the way to the top, though, and this tubing has a pretty narrow hole, almost too small for the screw attaching it to the retainer.

I used to have one in an old car, and I think the spool might be more like a bowden tube. The nested bits of the antenna were solid.  So, I could imagine a cable being attached to the inside of the top.  Shoving the cable up makes it go up, pulling it down makes it go down.  When up it was "solid", like a normal antenna that you could manually push up & down.