Broadband stripline to microstrip transition with constant impedance field matching section for applications in multilayer planar technologies

This paper presents a broadband Stripline-to-Microstrip transition with constant impedance section. In the transition the structural parameters of transmission line have been used to provide smooth electromagnetic field matching together with providing unchanged characteristic impedance along transition section. This solution eliminates the necessity of impedance transformer. The transition enables easy access to stripline circuits situated on the internal layers of multilayer structures by use of typical microstrip terminals. The transition has a simple structure for the ease of fabrication with low cost. The measured performance exhibits flat frequency response over broad bandwidth. The insertion loss is less than 0.5 dB and a return loss is better than 25 dB within frequency range 1 GHz to 10 GHz