Small antenna using 2-D interdigital composite right/left-handed (CRLH) transmission lines

In this paper, a small antenna is proposed based on the 2-D interdigital CRLH TL and the principle of design is described by the dispersion diagram. The interdigital capacitor is employed to enhance series capacitance so that it lowers a resonant frequency, while keeping a physical size same. The proposed idea is verified by way of the 3 × 3 interdigital CRLH TL. It is observed that the resonant frequencies are 3.028-GHz and 2.724-GHz corresponding to n=−1 and −2 modes, respectively. The realized antenna size is 13.5 mm by 13.5 mm, which is only 0.16λ
g
× 0.16λ
g
at n=−2 mode. Therefore, 90 % size reduction is achieved thanks to the 2-D interdigital CRLH TL, compared to a conventional patch antenna.