Comments on “An Asymmetric 2.4-GHz Directional Coupler Using Electrical Balance”

In the title paper, the authors proposed the model of the directional coupler using electrical balance based on a pair of coupled lines and presented its analysis. It is shown that the proposed equivalent circuit is incomplete without additional transmission line sections, and the analysis based on it cannot justify the claimed coupler performance or the design equations. A correct circuit model and the design equations are presented for the proposed coupler.