Log periodic design problem

Hi Guys


I am designing log periodic and trying to keep s11 below -10 i achieved but in frequency band of (.5GHz to .6GHz ) it gives higher s11(-5) how can i locate the problem , or the elements which are causing it. experts plz help.

In Log Periodic Antenna the individual components are often λ/2 dipoles, with alternating elements driven with 180° of phase shift from one another.
Check dimension and tune the spacing with near elements of the dipole element having length about 0.27m (λ/2 of 550MHz).
The characteristic of this dipole element should affect S11 at the frequency range you mentioned.