In this paper, we demonstrate six types of metamaterial absorbers （MMAs） by measuring their absorptivities in an X-band （8 12 GHz） rectangular waveguide. Some of the MMAs have been demonstrated previously by using the free space measurement method, and the others are proposed firstly in this paper. The measured results show that all of the six MMAs exhibit high absorptivities above 98%, which have similar absorbing characteristics to those measured in the free space. The numerically obtained surface current densities for each MMA show that the absorbing mechanism is the same as that under the free space conditions. Such a demonstration method is superior to the conventional free space measurement method due to the small-scale test samples required, the simple measure device, and its low cost. Most importantly, the proposed method opens a way to enable MMAs to be used in microwave applications such as matched terminations.
基片集成波导（SIW）技术正广泛应用于微波毫米波集成电路中。在W波段,为了对SIW元器件进行测试,必须对矩形波导-基片集成波导过渡结构进行研究。采用HFSS软件仿真和优化设计了一种耦合探针结构的矩形波导-SIW过渡。测试结果表明,一对过渡转换器与一段SIW所组成的背靠背结构在整个W波段的反射系数都小于-10 d B,而总插损在75~106 GHz的频率范围内都小于2 d B。
