Compact dual band crossover for 5G low and mid band applications using a metamaterial branch line coupler

This research paper introduces a compact dual-band crossover designed for the low and mid-band 5G frequencies at 0.7 GHz and 3.5 GHz. The innovative design is achieved by cascading two dual band branch-line couplers (BLCs), which utilize T-shaped transmission lines (TLs) with folded arms and stubs to reduce their overall footprint significantly. Additionally, the integration of metamaterial (MTM) structures, incorporating interdigital capacitor (IDC) unit cells, contributes to an impressive 90% size reduction compared to conventional components. The BLC's and crossover's performances were rigorously evaluated using CST Microwave Studio (CST MWS) simulations. Following successful simulations, the BLC and crossover were fabricated on a Rogers Duroid/RT5880 substrate, characterized by a dielectric constant of 2.2 and a thickness of 0.787 mm. A thorough comparative analysis between the simulated and measured results, alongside similar reported works, signifies the exceptional performance of the proposed BLC and crossover. These findings confirm their suitability for sub-6 GHz 5G frequency spectrum applications.