A Compact Dielectric-Loaded Log-Periodic Dipole Array (LPDA) Antenna

A compact, dielectric-loaded, and wideband log-periodic dipole array antenna operating between 200 and 803 MHz for VSWR less than 2 is presented in this letter. The antenna consists of sinusoidal dipoles and parallel stripline printed on a substrate partially loading an air layer, as well as two stepped dielectric materials with ε
_r
= 10. These two stepped dielectric materials are placed on both sides of the substrate. It is found that a remarkable lower frequency performance is obtained by using these two stepped dielectric materials, and the antenna's impedance matching performance is improved through the air layer partially loaded in the substrate. Good agreement is achieved between simulated and measured results. The antenna is also shown to work normally through the experimental results of VSWR under the 100 W continuous-wave power excitation for 30 min.