Dual-Band Multi-Beam Antenna Arrays Fed by Frequency-Dependent Feeding Network

This letter proposes a dual-band multi-beam antenna array (MAA) fed by a 4 × 8 frequency-dependent (FD) differential feeding network. Conventional dual-band MAAs predominantly employ dual-band couplers and phase shifters, which inherently restrict the dual-band operational bandwidth. A novel dual-band FD feeding network design method is proposed by employing components with FD characteristics in lower and higher bands, thereby expanding the dual-band operational bandwidth. The dual-band characteristics of the MAA are determined by a specific FD four-port component within the feeding network. A generalized design methodology for the FD four-port component applicable to all structures is introduced. This component functions as a through transmission line at the lower band and as a crossover at the higher band. By configuring the proposed dual-band frequency-dependent feeding network (FDFN), a dual-band MAA is designed, fabricated, and experimentally validated. This work demonstrates an innovative approach for maintaining improved bandwidth performance across two bands, offering significant advancements for applications requiring robust multi-beam capabilities.