Grating Lobe Suppression With Discrete Dipole Element Antenna Arrays

Antenna arrays with interelement spacing as integral multiple of wavelength λ have been absent in practical implementations despite their highly directive main lobe; the disuse is primarily attributed to the presence of grating lobes. This letter proposes a modification in a linear antenna array whereby the grating lobes are suppressed by up to 100% with an additional improvement in the directivity of main-lobe and reduction in other sidelobe levels. A new array factor is synthesized by replacing the individual elements in a linear array with a pair of elements called discrete dipole elements (DDEs); a background theory of spatial hard windowing is proposed for the synthesis of array factor. Array factors of linear array made of eight DDEs are compared to those of an eight-element linear isotropic array to validate the claims. The proposed DDE array is then fabricated using monopole antennas; a good agreement between measured, simulated, and analytical results is seen.