Proximity coupled fed wideband printed magneto–electric dipole antenna

Abstract

Results are presented fora wideband printed magneto-electric dipole antenna. The printed electric dipole and reflector are separated by an air-gap and is fed with a coaxial transmission line and a printed proximity coupled T-shaped feeding strip. The slot between the electric dipole halves forms the magnetic dipole radiating aperture. This feeding mechanism allows for good impedance matching at adjacent resonances of the electric and magnetic dipoles to achieve wideband operation. The two printed electric dipole halves are DC shorted to the reflector. The results show that this antenna can operate over a wide bandwidth with good gain, stable unidirectional radiation patterns and low cross polarization. The effect of the air-gap height and the relative permittivity of the substrate on which the dipole is printed are investigated. Results show that an optimum air-gap height for a specific substrate permittivity can be determined that will result in a gain with a small variation over the entire impedance bandwidth of the antenna. Simulated as well as measured results are presented for a prototype antenna with a small gain variation and overall dimensions of 1.33λ0 × 1.33λ0 × 0.19λ0. A measured impedance bandwidth of 54% with an average gain of 9.2 dBi is achieved.