A Novel Design of Dual-Band Rat-Race Coupler With Reconfigurable Power-Dividing Ratio

This letter presents, for the first time, the design of a reconfigurable rat-race coupler with dual-band operation. This device can offer power-dividing ratio of K
²
or ∞ at two different frequency bands. The proposed design also features low insertion loss, high port isolation, compact size, single control voltage, and minimal number of RF switches. For demonstration, both simulation and measured results of a 0.9-/2-GHz reconfigurable rat-race coupler implemented on microstrip are given.