Compact directional coupled-line coupler with independent power division ratios at dual bands

This paper presents the first coupled-line coupler that provides independent power division ratios at dual bands. In contrast with previous dual-band coupled-line couplers, the power division ratios k2 (f1) and k2 (f2) at each band (f1 and f2) can be independently controlled in order to satisfy the requirements of various communication protocols at different bands. Moreover, it has a compact size due to the usage of coupled lines rather than transmission lines. Explicit design equations and design guide of the coupler are provided. In this letter, one prototype of the proposed coupler is simulated, fabricated, and measured. It provides power division ratios k2 (f1) = 4 dB at f1 = 1 GHz and k2 (f2) = 8 dB at f2 = 2.4 GHz. The measured result agrees well with the simulation. © 2019, Electromagnetics Academy. All rights reserved.