A Design of Multibeam Antenna With 2-D Beam Steerable Capability

In this letter, a design of multibeam antenna (MBA) with two-dimensional (2-D) beam steerable capability is proposed. The proposed MBA is composed of a circular 4 × 4 butler matrix (BM) and a 2 × 4 patch antenna array. And the 2 × 4 patch antenna array consists of four two-element subarrays uniformly arranged along the
E
-plane. By introducing the switching diodes in the subarray and controlling the switching diodes
on
and
off
, elements of the subarray are excited through the paths with different lengths, and the beam of the subarray is steered subsequently in the
H
-plane. The circular 4 × 4 BM is designed as the beamforming network to excite the four subarrays uniformly arranged along the
E
-plane and steer the beam in the
E
-plane. The proposed MBA can generate 12 beams by selecting the excitation port and controlling the
on
–
off
state of the switching diodes. To validate the performance of the proposed MBA, a prototype is fabricated and measured. By design, the dimension of the designed MBA has reduced to 2.9 λ
₀
× 1.3 λ
₀
. The designed MBA operates at 5.7 GHz, and the results show that the beams of the MBA can cover the range of ±36° in the
E
-plane and ±22° in the
H
-plane, respectively.