Phase Center Variation Stabilization for Log-Periodic Antennas

Proposed is a novel method for stabilizing phase center location variation (PCLV) of Log periodic antennas based on modifying excitation current phase (ECPh). To validate this technique, an ultra wideband planar log-periodic dipole array antenna (PLPDA) was designed for operating in L and S bands (1-4GHz) with 12 dipoles. Defected microstrip structure (DMS) and microstrip meander structure (MMS) investigated for ECPh linearization and so, MMS was used to modify ECPh as the best structure with highest dynamic range based on limited length between adjacent elements and antenna impedance matching. Finally, modified PLPDA (MPLPDA) was designed and fabricated with 6 MMS structures without any changes in antenna dimensions. Measurement and simulation results show that radiation patterns of both antennas have a good conformity while the PCLV of MPLPDA is stabilized. Moreover, MPLPDA has a -10dB bandwidth of 4.5 GHz.