Miniaturized zeroth-order resonant antenna using coupling-enhanced meandered structure

A zeroth-order resonant (ZOR) antenna based on the coupling-enhanced meandered unit cells is presented. The proposed unit-cell prototype is able to efficiently increase both the parasitic inductance L_R and coupling capacitance C_L in the series branch of its equivalent circuit model. By connecting one end of the meandered cells to the ground plane, the resulting structure with such unit cells resonates at the resonant frequency of the series LC tank in the circuit model and can be considerably miniaturized by means of effective increases in L_R and C_L. The proposed ZOR antenna is composed of two meandered cells, each of which occupies only 0.036λ₀ × 0.083λ₀ at the resonant frequency. Experimental results show that our ZOR antenna provides a fractional bandwidth of 3.6% and the peak radiation gain of 1.24 dBi while requiring a noticeably compact footprint of 0.05λ₀ × 0.25λ₀ at the operating frequency.