Abstract: To realize ridged waveguide-to-microstrip RF signal transition, a novel circuit without contact of ridged waveguide-to-microstrip adapter is provided in this paper. The adapter is very suitable for engineering application due to broadband, low insertion loss and stable electrical property. A method of covering C/X/Ku broadband power combining based on non-contact ridged waveguide-to-microstrip adapter and Lange coupler is proposed by theoretical analysis and simulation calculation. A high efficiency 2-way power combining module with ridged waveguide ports is designed by this method. Experimental results show that passive combining efficiency is above 87% within the band of 6-18 GHz. This cirtuit combines the output powers of 2 MMICs,each of which has the typical output power of 12W. Saturation power is above 20 W, and PAE is up to 28. 9%, within the operating band. This broadband power combining amplifier with ridged waveguide interfaces has high RF power capacity, and easy to use ridged waveguide power combiner to perform high efficiency secondary combination,it gives a solution for solid state power amplifier with higher output power at 6-8 GHz.