Compact microstrip antenna with metamaterial for wideband applications

An improved metamaterial antenna, with a compact size of 27.8 x 31.9 x 0.794 mm3, fed by an offset-microstrip line, is proposed. The total size is slightly reduced and the measured impedance bandwidth is 4.08-7.83 GHz for a return loss of \mid S11\mid < -10 dB. Compared with the original patch antenna, the bandwidth of the proposed antenna is 550 MHz broader and has a lower resonant frequency. The simulated gain of the antenna is more than 2 dB, with a peak of about 6 dB at 6.8 GHz. Moreover, the antenna has strong radiation in the horizontal direction for some specific applications within the entire band.