Ultracompact Pattern-Reconfigurable Huygens Dipole Antenna With Uniform Polarization and Quasi-Isotropic Coverage

An ultracompact broadside and backfire pattern-reconfigurable Huygens dipole antenna (HDA) is developed, which achieves a quasi-isotropic and uniformly polarized radiation pattern. A novel reconfiguration scheme is adopted that only switches the phase of the electric dipole (ED) by 180° in an electrically small Huygens (complementary) source antenna. Its magnetic dipole (MD) is left unchanged. The system is realized by an Egyptian axe dipole (EAD), a reconfigurable capacitively loaded loop (CLL) with one PIN diode, a reconfigurable short driven dipole with one PIN diode, one capacitor, four dc biasing lines, and four RF chokes. The antenna radiates a broadside Huygens pattern when both the diodes are off. By turning on the diode in the middle of the additional thin strip below the top strip of the CLL, a 180° phase alteration will be obtained and a backfire Huygens pattern will be realized. To achieve an overlapped operating band for the two pattern modes, the diode in the short driven dipole is turned on to extend its length to compensate for the ensuing impedance mismatch. The measured results confirm the simulations. The antenna is attractive for wireless applications that require compact antennas with large radiation coverage and uniform polarization.