A Millimeter Wave Metamaterial Based Array Antenna Structure with Dual-Band Resonance

The metamaterial (MTM) structures are widely used in characterizing antenna response in terms of bandwidth, gain, impedance, and isolation. This article presents a novel MTM structure through which the desired resonance is generated. To fully demonstrate its functionality, the array of MTM unit cells is laid before the array antenna structure on the same layer. The designed array antenna has a resonance at 30 GHz with broadside radiation. The designed MTM has dual pass-band and dual stop-band. We have used the dual pass-band characteristics to generate the dual resonance. The MTM inherits tranverse electric (TE) mode at 30 GHz and traverse magnetic (TM) mode at 32.5 GHz. The energy to the MTM is capacitively coupled through the array antenna, as a result, the impedance matching is greatly affected due to the spacing between the array and MTM. Thus, the proposed structure is able to achieve dual resonance at 30 GHz and 34 GHz with |S11| =10 dB impedance bandwidth ranging from 29.6-30.56 GHz and 32.48-34.76 GHz for 0.3 mm spacing. Similarly, for 0.2 mm spacing, bandwidth ranges from 29.8-30.68 GHz and 32.2-34.84 GHz. The proposed structure is able to achieve a maximum gain of 10 dBi and \mathbf{5.7 dBi, at respective bands.