In this paper, a simple and effective side-lobe suppression technique is proposed by using integrated high refractive index matematerial (HRIM). It is known that current reversal, which occurs at the third harmonic of the dipole natural frequency, disturbs the omnidirectional radiation pattern of a dipole antenna, and the main beam splits into two side lobes. For suppressing the two side lobes and maintaining consistent radiation pattern purposes, two regions of HRIMs are integrated along the side-lobe radiation direction of a reflector-backed dipole antenna to tilt the two side lobes toward the broadside radiation direction. The HRIM is constructed with 2X3 H-shaped unit-cells periodically printed on the single side of dielectric substrates. The beam-tilting approach described here uses the phenomenon that the EM wave undergoes a phase shift when entering a medium of different refractive indices. Simulation and measurement results show that by implementing the HRIMs, the two side lobes are tilted toward the broadside radiation direction, and as a result, the side lobe is suppressed, and radiation consistency for the first and third harmonic resonances is realized. Moreover, the antenna gain for the third harmonic is achieved as high as 7.8 dBi, which is an increase of approximately 3 dBi compared with the fundamental resonance.
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