A compact diplexer using meander-line resonators and a new coupled junction for 5G and WiMAX application

In this paper, a miniaturized microstrip diplexer designed on an FR4 substrate material is presented. The diplexer operates at 2.4 and 3.5 GHz, responding to the demands of 5G and WiMAX applications, respectively. It consists of two distinct bandpass filters (BPFs) formed using the meandrous line, which are combined using a coupled-junction. An electromagnetic (EM) simulator was used to characterize the frequency responses of the designed diplexer. The results show that the proposed diplexer exhibits excellent isolation, exceeding 28.5 dB throughout the operating frequency range. Additionally, the passband insertion losses are approximately 1 dB, while the return losses measure around 39 and 57 dB for the both channels, respectively. Furthermore, the manufactured diplexer is compact with final dimensions of 28.5 × 20 mm2. These results confirm the suitability of the proposed diplexer for the intended applications.