Attenuator using lossy left-handed transmission line and its applications

This paper proposes a design of a variable attenuator based on meta-material structuring and its application. The unit-cell of attenuator, based on the lossy transmission line, consists of the composite right/left-handed transmission line (CRLH-TL) and PIN diodes to control internal loss according to resistance variation of diode. Also, to reduce the initial losses, a parallel connection of PIN diodes is used. Because of constituting a periodic structure to increase attenuations, an attenuator with a cascade unit-cell is connected. The attenuation quantities of the unit-cell are about 10 dB and phase variations are a maximum of 15° at 1.5 GHz ~ 2.5 GHz. To attenuate more than 10 dB, the unit-cell of attenuator must be connected to a cascade. Also, its application is represented by a vector modulator.