Bandwidth Extension of Planar Microstrip-to-Waveguide Transition by Via-hole Arrangement

The conventional millimeter-wave transitions that couple the fields of microstrip line and waveguide via patch resonance are not satisfied the demand of wideband and high transmission performance. Therefore, a novel design technique of microstrip-to-waveguide transition with a simple via-hole arrangement surrounding waveguide is proposed. By controlling the relative position of via holes with waveguide and microstrip line, the proposed transition can be operated over a quite broad frequency bandwidth due to its double resonance. The bandwidth of 10 GHz (13.5%) is obtained where the reflection level is lower than-15 dB. Furthermore, bandwidth extension depending on via-hole arrangement is investigated by electromagnetic simulations in this study.