J-Pole antennas are one of the true works of electrical engineering that gives us a smaller footprint vertical with no need for a ground plane. But how do these things work?
Here is a great presentation from Dr. Ed Fong WB6IQN explaining.
Other articles and information on J-Poles available here:
The DBJ-1: A VHF-UHF Dual-Band J-Pole
DBJ-2 Dual Band Roll-Up Antenna