Gain-Enhanced Planar Log-Periodic Dipole Array Antenna Using Nonresonant Metamaterial

In this communication, a novel nonresonant metamaterial (MTM) structure is proposed to enhance the gain of the clamped-mode planar log-periodic dipole array (CMPLPDA) antenna fed by substrate integrated waveguide. The proposed MTM structures composed of a series of metallic semiring patches are printed on both sides of the antenna substrate, featuring low loss, broadband, and easy integration. Different arrangements of the nonresonant MTM with respect to the dipoles of the CMPLPDA antenna are investigated and compared. The proposed gain-enhanced method based on the nonresonant MTM has been studied through both numerical simulations and experiments. Compared to the original CMPLPDA antenna without any MTM inclusions, the proposed CMPLPDA antenna fully loaded with nonresonant MTM inclusions exhibits a gain enhancement of at least 1.6 dB (up to 4 dB at 27 GHz) within the operating band of 26-40 GHz in the simulations, which is also validated by the experiments.