(b)
Fig. 3 parameter sweep of Cp and Lp. (a) S21 with a variation of Cp.(b) S21 with a variation of Lp.
Adding matching circuits for each port, a very good isolation with 50dB, and good system efficiency near 100% are achieved in Fig.4. Fig.5 shows that the common mode is excited in the x-axis of Port1, and differential mode is excited in the y-axis of Port2. In the 90-degree rotation, the differential mode is excited in the x-axis of Port1, and common mode is excited in the y-axis of Port2. There is a characteristic of orthogonal radiation patterns.