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