Compact Microstrip Filtering Power Dividers With Good In-Band Isolation Performance

Compact and high isolation microstrip filtering power dividers (PDs) have been presented in this letter. In order to effectively reduce circuit area, the compact folded net-type resonator is selected to build up the resonator-based PDs with a filtering response. The highly symmetric structure of the divider provides not only a good in-band isolation performance, but also a low magnitude imbalance and phase imbalance. For the demonstration, two design examples of in-phase and out-of-phase PDs with second-order Chebyshev filtering response have been designed and fabricated with microstrip technology. As a result, both dividers have an extremely small size of 0.19 λ_g by 0.19 λ_g. The measured results are in good agreement with the simulated predictions, showing that better than 30 dB isolation within the whole passband is achieved with a tradeoff of the bandwidth.