Wideband unequal filtering power divider with high power dividing ratio based on line‐inserted method

Abstract

In this study, a type of wideband-filtering power divider (FPD) with high power dividing ratio (PDR) is proposed based on the line-inserted method. The proposed wideband FPD is implemented by inserting a quarter-wave line in front of the conventional wideband FPD. With the inserted line acting as part of each filtering branch, an additional in-band pole is generated, and the requirement for high input impedance can be relaxed. Consequently, both the fractional bandwidth (FBW) and maximum PDR can be enhanced. To enforce the effectiveness of the inserted line, a corresponding design method for the wideband FPD is proposed and demonstrated. Initially, a wideband filter involving the inserted line is synthesized. Then, the synthesized filter is used for implementing wideband FPD using voltage transformers. Finally, the voltage transformers are successfully absorbed into the filtering branches. Examples of 4:1 and 12:1 FPDs operating at 1.8 GHz are designed and fabricated with specified FBWs of 100% and 88%. The measured PDRs are 3.9:1 and 11.2:1 with corresponding bandwidths of 103.9% and 88.3% (|S 11|< –10 dB), respectively. The proposed wideband FPD exhibits a higher PDR, wider bandwidth, equal-ripple response, and filtering embedded compared with the conventional ones.