Electrically small tunable antennas using split ring resonators

Presented are tunable electrically small antennas composed of split ring resonators (SRRs), which are used to reduce antenna size. To control the resonance frequency, a lumped inductor is inserted between the SRRs and the ground. The proposed antenna operates within Korean personal communication services (PCS) frequency bands of 1750-1870-MHz, and the size of the antenna is 1-33-₀×1×33×₀ with an operating frequency of 1800 MHz. In spite of its small size, the radiation efficiency and 10 dB bandwidth were measured as 82 and 2.4 , respectively. Good agreement between the predicted and measured results ensures the validity of the design method to provide a frequency adjustment using lumped inductors in small SRR antennas.