Dual‐band balanced‐to‐unbalanced filtering power divider by coupled ring resonators

A dual‐band balanced‐to‐unbalanced filtering power divider by coupled ring resonators is proposed. Two passbands can be easily realised by the two coupled ring resonators. Three transmission zeros near the two passbands are used to improve the selectivity. The common mode can be easily suppressed by the bandstop performance of the open stubs. A fabricated prototype ( ε r = 2.65, h = 1 mm, tan δ = 0.003) with centre frequencies located at 2.82 and 3.22 GHz is designed and measured to prove the proposed methods.