Integrated SIW filter and microstrip antenna

A novel design of integrated Substrate Integrated Waveguide (SIW) filter and microstrip antenna is proposed. In the first step, the methodology consists of synthesising the subsystems combining a filter and an antenna using lumped lowpass prototype networks. To realise the concept, the filtering and radiating functions are combined using multilayer technology on a printed circuit board (PCB). The design is based on the circular cavity structure using TM₀₁₀ mode for the filter and TM₁₁₀ mode for the antenna. To prove the design technique, modes in the SIW filter and in the microstrip antenna are coupled by capacitive circular iris at the common ground plane. Good antenna characteristics such as gain and radiation pattern illustrate and prove the validity to integrate directly SIW and microstrip technology without the need to use any external matching circuit. This design provides an alternative solution for combining filter and antenna subsystems in the RF front end that is useful for wireless communications systems.