Theory behind the UltraWide Band character in the attached paper.

[vishal_sonam]

Hello I working on the attached paper and i want to know to the reason behind the enhanced bandwidth.
What happened to it using the L shaped ground plane that helped to have wide band characteristic.

with best regards.
Vishal

 

[AndreyG]

If vertical part of L is removed the resulting structure is typical uvb antenna.
Vertical part works as reflector i think, makes the antenna directional.