Increasing the bandwidth of electrically small supergain antennas using low-Q electric dipoles

The quality factor (Q) of electrically small two-element supergain arrays with realized gains approaching 7 dB rapidly increases and thus the bandwidth rapidly decreases with decreasing electrical size of the array. To increase the bandwidth we replace the original two electrically small resonant electric-dipole antenna elements of the supergain array with the recently designed magnetic-shell electric-dipole antennas with Q values that approach the Q lower bounds for their shape (the Chu lower bound for spherically shaped antennas). We find that a 15%increase in the bandwidth of the resonant elements produces a 40% increase in the bandwidth of the two-element supergain array.