Broadband Inset Dielectric Guide Coupler

The inset dielectric guide (IDG) represents an easy-to-fabricate alternative to image line that is also less sensitive to loss by radiation at discontinuities. A multihole coupler has been realised showing a very flat coupling characteristic over a waveguide bandwidth. The frequency dependence of the pure coupled IDG structure is compensated by the use of holes in the separating wall between the two IDGs. The balance between the two coupling mechanisms creates the broadband flat frequency response. Measured values show very good agreement with predicted values, and this approach opens new avenues in the design of IDG devices and subsystems.