Voltage controlled variable attenuator with adaptive frequency characteristics

In the broadband wired communication, it is strongly required to equalize attenuation characteristics in transmission lines. In this paper, the variable attenuator equalizer using 90-degree hybrid coupler is proposed which has the lowest return coefficient. Experimental results show the variable attenuator can be realized in the 700 to 1050MHz frequency range. Further result shows that the attenuation profile can be controlled in real time with variable attenuation equalizer using PIN diode. From these results, adaptive attenuator with variable attenuation characteristics can be realized. © 2018 The Institute of Electrical Engineers of Japan.