Design and Optimization of Millimeter-Wave Microstrip-to-Waveguide Transition Operating over Broad Frequency Bandwidth

摘要

A broadband microstrip-to-waveguide transition is developed in the millimeter-wave band. No additional parts and complicated structures are needed to extend the frequency bandwidth. Only the simple and novel geometrical features are added in the printed pattern on the substrate. The proposed transition operates over a quite broad frequency bandwidth due to its double resonance. The two resonant frequencies are controlled by adjusting dimensions of the structure according to the required bandwidth, the reflection level and the center frequency. Two versions of the transition are designed and reliability is confirmed by experiments in the millimeter-wave band. The design frequency is 76.5 GHz. Bandwidth 12.9 GHz (16.8%) is obtained where the reflection level is lower than -30 dB. In the other design for broadband, the bandwidth for reflection level lower than -20 dB results in 24.9 GHz (32.5%). Furthermore, it is confirmed in the experiment and simulation that the center frequency is controlled from 75.3 GHz to 78.7 GHz by changing the geometry of the printed pattern.