Design, fabricate and test of a new kind of high power microwave directional coupler

In this paper, a new kind of high power microwave directional coupler operating at 1.72GHz to 2.61GHz is presented. To get a directional coupler with very weak coupling but high power capacity, a two-stage coupling strategy is proposed. Multi-holes coupling structure is used for the first coupling stage, and double cross-aperture is used for the second coupling stage. The coupling factor´s variation trends of these coupling structures can be designed to be opposite. Then a very flat frequency response will be got. The two-stage directional coupler is designed and fabricated. The measurement results show that this directional coupler has a good performance. The deviation of the coupling is smaller than 0.8dB, and this directional coupler can work normally when a 2MW pulse microwave power put in it. The potential peak power capacity of this directional coupler could be much higher.