A DUAL-POLARIZED TAPERED SLOT ANTENNA ARRAY WITH REDUCED PROFILE HEIGHT
Abstract
An element of a planar Vivaldi antenna array designed to operate on two linear polarizations is considered. The antenna array element is made of a dielectric substrate with double-sided metallization and consist of a tapered slot, a balun and a short section of microstrip line. At the same time, the length of the balun is reduced by making it sine-shaped and, thus, the longitudinal size of the Vivaldi element and the profile height of the entire antenna array are reduced. The connection between adjacent elements of the antenna array is carried out using metal posts placed on a metal screen. The results of a numerical study of the matching and radiation characteristics of a unit-cell with periodic boundary conditions on the faces are presented. It is shown that despite the reduction of the length of the Vivaldi antennas, due to the miniaturization of the balun, there is no narrowing of the operating frequency band in the antenna array. The calculated gain of the unit-cell is close to the theoretically achievable directivity of the aperture of the same area as the unit-cell. The broadside radiation efficiency does not fall below 75% over the entire operating frequency range. A study of the radiation characteristics when scanning the beam of the radiation pattern in the E-, H- and D-planes showed the possibility of deflecting the beam by an 60º angle without the appearance of antenna array blinding effects. The effect of small isolation between the nearest orthogonal elements of the antenna array on the matching at the input of the elements when scanning a beam in a diagonal plane is shown. The presented results of a study of the cross-polarization characteristics of the element when the beam is deflected at an angle of 45º in the D-plane show that the crosspolarization gain of the unit-cell is less than the co-polarization gain by an amount from 6 to 15 dB. The operating frequency band, determined by the VSWR≤3 level, ranged from 915 to 7500 MHz
