Ultralow-Profile, Electrically Small, Pattern-Reconfigurable Metamaterial-Inspired Huygens Dipole Antenna

An ultralow-profile, electrically small, pattern-reconfigurable metamaterial-inspired Huygens dipole antenna is presented that operates near 1.5 GHz. The design incorporates two pairs of magnetic and electric near-field resonant parasitic (NFRP) elements and a reconfigurable driven element. A pair of p-i-n diodes is integrated into the driven element to enable the antenna pattern reconfigurability. By switching the ON/OFF states of the diodes, the antenna can realize two independent unidirectional endfire radiating states whose peaks point in antipodal directions and a bidirectional endfire radiating state. The measured results, in good agreement with their simulated values, demonstrate that although the antenna is electrically small ( ka = 0.98) and ultralow profile ( 0.0026\lambda _{0} ), it can realize uniform peak realized gains (RGs) of ~5.4 dBi, front-to-back ratios (FTBRs) of ~13.3 dB, and radiation efficiencies of (REs) ~85% in its two oppositely directed endfire states, and a RG of ~3.55 dBi and RE of ~87% in its bidirectional endfire state.