Linear Antenna Array With Large Element Spacing for Wide-Angle Beam Scanning With Suppressed Grating Lobes

An array with large element spacing is designed for wide scanning. The element is designed to suppress the grating lobe by combining two radiation modes. The two modes are the
$\mathrm{T}{\mathrm{E}_{\boldsymbol{1}\delta 1}}$
mode of a square dielectric resonator antenna (DRA) and the TM
₀₁₁
mode of a monopole. The proper phase and magnitude combine the two modes to achieve the required radiation pattern. The element radiation pattern has an asymmetric radiation pattern with the main beam pointing to the anticipated scanning region and a low radiation level in the region of the expected grating lobe. A linear four-element array with an interelement spacing of 0.95
λ
₀
(
λ
₀
is the operation wavelength) is designed, fabricated, and measured for beam scanning in the E-plane to verify the design concept. The array's grating lobe is reduced by more than 11 dB within the scan angle of 15°–60° and bandwidth of 4.51–5.32 GHz. Good agreements between simulated and measured results are observed.