Compact Low Frequency Varactor Loaded Tunable SRR Antenna

An electrically small tunable split ring resonator antenna is presented. The resonance of the antenna is dependent on the resonance of the split rings. By loading the split ring with varactor diodes, the antenna operating frequency can be reduced and tuned. By applying a DC voltage of 1 to 9 V, the antenna is capable of tuning within the frequency range of 365 MHz to 500 MHz with the measured reflection coefficient of -10 dB. The antenna is compact and low profile. At the operation frequency of 365 MHz, it measures 0.095 λ×0.046 λ×0.001λ , where λ is the free space wavelength.