Using heat-activated nitinol metal, researchers have devised a reversible, shape-shifting, conical spiral antenna that needs ...

these can be loading or phasing coils to change the antenna’s performance. Usually they are to help pack a larger antenna into a smaller space, which makes the overall length less useful as a guide.

PCB motors are useful things. With coils printed right on the board, you don’t need to worry about fussy winding jobs, and it’s possible to make very compact, self contained motors.