Researchers introduced a novel one-dimensional switching matrix that achieves a reduction in the number of layers when compared to conventional matrices.
Antennas are central to wireless communication technologies. With emerging wireless technologies such as 5G, there will be an increasing demand for multibeam antennas that are capable of efficiently handling multiple beams. This is because the millimeter-waves are prone to interference, so transmitting multiple waves from multiple beams would increase the probability of waves reaching the receiver.
The multibeam antennas use beamforming networks (BFNs) like the Butler and Nolen matrices that control and direct output signals using a combination of electrical components including phase shifters and directional couplers. The type of BFNs determine the structure of the circuit and the number of layers the circuit would need to generate a certain number of beams.
Researchers from Tokyo Institute of Technology look to improve the BFNs to provide low cost-solutions for single-layer printed circuit board (PCB) implementation. The researchers have introduced a novel one-dimensional switching matrix that achieves a reduction in the number of layers when compared to conventional matrices.
Prof. Jiro Hirokawa from Tokyo Tech explains, “We have numerically found the parameters of the directional couplers (including crossovers) and phase shifters that determine the structure of the circuit for an arbitrary number of beams in the generalized configuration of the orthogonal matrix forming multiple antenna beams. The discovery improves over previously known solutions addressing the specific challenges of planar implementation.”
The novel topology overcomes the limitations of conventional beamforming matrices. Compared to conventional Butler and Nolen matrices, the novel matrix topology also reduces the number of layers when the number of beams is five and above, reaching a reduction ratio of 38 percent with eight beams.
“This reduction ratio is very useful for passive antenna orthogonal beamforming matrices. It is expected to benefit the design of next-generation wireless mobile systems and satellite communication microwave payloads,” explains Prof. Hirokawa.
The work is described in the IEEE Journal of Microwaves.