Design of Microwave Radiating SIW Diplexer

This paper presents a new design for the integration of microwave SIW diplexer and antenna using multilayer planar technology. The design process started with the network synthesis of the SIW diplexer integrated with patch antenna using lumped lowpass prototype networks. The circular cavity structure using TM
₀₁₀
mode is employed in the design of the diplexer and TM
₁₁₀
mode for the antenna. To prove the design concept, modes in the SIW diplexer and in the microstrip antenna are coupled by capacitive circular aperture at the common ground plane. The proposed design is fabricated with standard printed circuit board technology and will be operating at 2.2 GHz and 2.4 GHz each suitable for LTE/WiFi applications. The performance of the proposed design are verified through both simulation and measurement. The measured results showed a good agreement with passband return loss greater than 10 dB in both bands and 20 MHz bandwidth with good radiation pattern and radiation gain measured to be 5.55 dBi and 5.84 dBi.