Dual-Band Multibeam Antenna Arrays Fed by Frequency-Dependent Feeding Network

This letter proposes a dual-band multibeam 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 FD 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 multibeam capabilities.