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.