Wideband folded mushroom zeroth-order resonance antenna

In this study, a wideband folded mushroom zeroth-order resonance (ZOR) antenna is presented. To obtain a wide bandwidth, the frequency of the TM₀₁₀ (λ₀/2) mode is down-shifted to the frequency of the ZOR mode by folding a mushroom structure without any additional structure. Thus, the folded mushroom antenna operates over two modes, resulting in a wide bandwidth. The antenna has a dimension of 0.365λ₀ × 0.247λ₀ × 0.182λ₀ at the centre frequency. Its 10 dB fractional bandwidth is measured as 68.3%. The maximum gains of 3.32 and 3.41 dBi are measured at the ZOR mode and the TM₀₁₀ mode, respectively. Finally, the measured results show good agreements with the simulated results.