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 λg by 0.19 λg. 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.