A novel Left-Handed NRD guide directional coupler without LSE11 mode conversion loss

In this paper, the possibility of eliminating LSE₁₁ mode conversion loss in LH-NRD guide asymmetric discontinuity structure is discussed and confirmed for the first time. A LH-NRD guide directional coupler which eliminates both radiation loss and mode conversion loss is proposed; the scattering and coupling characteristics of the coupler are carefully investigated by a method which combines the building block approach and multimode network theory with a rigorous mode-matching procedure. Numerical results are given to show the expected mode conversion loss free feature. It should be stressed that the proposed coupler is of high efficiency due to lack of both radiation and mode conversion loss, which makes it very promising in millimeter wave integrated circuit environment.