Metamaterial-based wideband shorting-wall loaded mushroom array antenna

A shorting-wall loaded metamaterial mushroom array antenna is proposed for bandwidth enhancement and compact design. Owing to the shorting-wall loading, the lower frequency region of the right-handed branch of the composite right/left-handed (CRLH) mushroom structure is exploited. The operating modes of the antenna are investigated. The antenna prototype at 5-GHz band exhibits 26% impedance bandwidth (|S<sub>11</sub>|<;-10 dB) with a compact size of 0.65λ<sub>0</sub> × 0.61λ<sub>0</sub> × 0.06λ<sub>0</sub> (λ<sub>0</sub> is the center operating wavelength in free space).