A Dielectric Waveguide Diplexer for 5G Applications

This paper presents a new dielectric waveguide diplexer based on the hexagonal solid dielectric waveguide resonator (DWR). The proposed design utilizes a common resonator to connect the two filters for the transmitter and receiver ends. By adjusting the blind holes positioning in the DWRs and the coupling windows, the frequencies and coupling coefficients of the filters can be tuned independently. A design example, with one filtering band from 3.4 GHz to 3.5 GHz and the other from 3.6GHz to 3.7 GHz, is designed and simulated. The simulated in-band return losses are better than 20 dB. One transmission zero is generated at the upper sideband of the lower channel and one transmission zero is generated at the lower sideband of the upper channel based on the cascaded-trisection (CT) coupling structure, making the in-band isolations greater than 25dB. The results indicate that the proposed dielectric waveguide diplexer exhibits good performance and is suitable for wireless base station equipment in the 5G communication infrastructures.