Design of millimeter wave substrate integrated waveguide diplexers

In recent years, the use of substrate integrated waveguide (SIW) has increased: there has been a flood of papers in the literature focusing on both passive and active devices, such as filters and amplifiers. In terms of passive devices, a lot of work has been done on filters. However, only a limited amount of work has been carried out on diplexers where experimental validation has been limited to below K band.