[Elecraft] [KX3] Urban stealth HF: Inside-the-backpack loop antenna?

[Jim Shepherd]

Cut a large double sided piece of double sided circuit board to fit the
backpack.
Etch the back side with a symmetric Hilbert curve split into 2 columns fed
at the bottom center and the two columns attached at the top.  Leave the
other side as a solid ground plane... It will take some work to make a
matching network, but the length of the 'curve' can easily be a half wave
on 20 meters. It will be directional to your rear as you walk along.

Jim W6US