Demonstration of an antenna gain enhancement by a metal hole array at 125 GHz

We show a metal hole array (MHA) with wavelength-sized periodic apertures in a metal plate can be applied as an antenna gain enhancer in the millimeter-wave range. In the proof-of-concept experiment, the MHA was placed in front of the horn antenna (gain: 23 dBi) and antenna gain enhancement and the wavefront conversion were demonstrated, where the spherical wavefront of the millimeter-wave (125 GHz) was transformed into a planar shape by the MHA. We experimentally demonstrated that the MHA enhances the antenna gain by approximately 1.9 dB. The bandwidth of the gain enhancement was approximately 1.2 GHz.