Tunable stripline circulator with isolation control using metamaterial cells

In this paper, a tunable stripline circulator with isolation control is designed using metamaterial cell. Our cells have two different configurations: the first one consists of the case 00 where each of the gaps g1 and g2 is closed. The second one represents the case 11 where the structure is in the open switch state (gaps g1 and g2 are open). We can flip between the desired behaviors by external commutation systems (using MEMS or PIN diode). Circulator’s frequency tunability is usually achieved by varying the static external magnetic bias. However, the isolation control arises by changing the states of the unit cell (11 or 00). The results show that it is possible to control the isolation characteristics of our circulator by operating the switching devices. The maximum isolation contrast between the cases 11 and 00 is 8.09 dB with a bandwidth of about 0.52 GHz for Hi = 1.1 kOe.