Innovative Design of a Compact Diplexer Using Heterogeneous Filters for 5G and WiMAX

The rapid advancement of wireless communication systems, such as 5G and WiMAX, demands compact, efficient, and high-performance diplexers that can operate effectively at multiple frequency bands. This necessitates their miniaturization without compromising performance. This paper presents the design of a miniaturized microstrip diplexer using heterogeneous bandpass filters (BPFs) and a coupled junction, on a Rogers RT/Duroid 5870 substrate. The ADS electromagnetic simulator was used to characterize the frequency responses of the proposed diplexer. It exhibits satisfactory isolation, in excess of 40 dB over the entire operating frequency band from 3.5 to 5.2 GHz. Additionally, insertion losses in the passband are less than 0.8 dB, the diplexer also achieves return losses of approximately 28 dB and 12.8 dB for the two respective channels. Additionally, the overall size of the presented diplexer measures <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">${21} \times {15}\ \text{mm}^{2}$</tex>. These findings validate that the proposed diplexer is highly suitable for 5G and WiMAX applications.