Active Metamaterial-Inspired Broad-Bandwidth, Efficient, Electrically Small Antennas

Realistic designs of broad-bandwidth metamaterial-inspired electric and magnetic antennas are characterized numerically. By augmenting their narrow bandwidth counterparts with internal non-Foster elements, active metamaterial unit cells are introduced as near-field resonant parasitic (NFRP) elements. The driven and NFRP elements in each presented case are designed to achieve nearly complete matching of the entire system to a 50- Ω source without any matching network and to yield high radiation efficiencies over their FBW_{10 dB} bandwidths that are more than 75 times their original values.