Radiation Efficiency Improvement of Zeroth-Order Resonator Antenna

The radiation as well as antenna efficiency of very thin profile zeroth-order resonator (ZOR) antenna, implemented in negative phase velocity (NPV) microstrip transmission line (TL) structure, has been solved by the method of moment simulator IE3D. The radiation is investigated using individual portions of the ZOR antenna that shows significant values of the surface current density. Dominantly radiating parts have been identified, geometrically emphasized by means of the increase in the antenna height over the ground plane from 1/105 to 1/8 lambda(0). The measured parameters of the improved antenna prototype have been enhanced so they reached the following values (compared to original ones): gain 5.0 dBi (-3.0 dBi), antenna efficiency 97.7% (9.5%).