Sparse Antenna Array with Flat-Top and Sharp Cutoff Radiation Patterns

A sparse antenna array with flat-top and sharp cutoff radiation patterns is presented in this work. The array consists of 16 antenna elements, which is realized by applying a symmetrical sparse configuration with uniform excitation phase. This configuration simplifies the excitations of the array while maintaining excellent radiation performance. The dual-band dual-polarized base station antenna based on the proposed sparse antenna arrays in the bands of 1.71-2.17 and 2.30-2.69 GHz is fabricated and measured. The measured results are in very good agreement with the predicted ones, showing that the port reflection coefficient is less than -15.0 dB, and the isolation is greater than 28.5 dB. In addition, the array has a gain of 10.1-12.3 dB, a half-power beamwidth (HPBW) of $45^{\circ } \pm 5^{\circ }$ in both the horizontal and vertical planes, a cutoff transition of less than 17.4° from -3 to -20 dB between the main beam and the sidelobe area, and a sidelobe level suppressed to below -21.1 dB. Apart from the good radiation performance, the proposed sparse antenna array has a compact size with very few antenna elements, which is very suitable for communication in a crowded scene.