Experimental study of dielectric waveguide Y-junctions for millimeter-wave integrated circuits

Symmetric and asymmetric Y-junctions have been fabricated from rectangular dielectric image line, and the transmission and reflection characteristics have been measured in the 20-26 GHz range. The tested symmetric Y-junction operates as a near-3-dB power divider for the junction half-angle below about 20 deg. The maximum allowable junction angle of the symmetric Y-junction is discussed, which is very important for millimeter-wave integrated-circuit applications. It is shown that the asymmetric Y-junction can be used as a directional coupler because of the controllable splitting ratio and high isolation. Results for the asymmetric Y-junction with a gap are also presented.