Plane Directional Coupler Devices Engineering Studies

The directional coupler may be regard as one kind of the directive power divider, and have been widely used in the microwave system. In this work, three novel directional couplers have been designed, including the conventional four-port planar hybrid ring coupler with addition introduction of the fifth port, a compact planar magic-T implemented by combination of oplanar waveguide (CPW) and slot lines, parallel-line directional coupler based on composite right-hand/left-hand materials.The proposed new design of planar hybrid ring coupler with another additional port demonstrates substantially improved coupling and phase characteristics over a very broad frequency range. A prototype was fabricated and measured,The magic-T implemented by combining coplanar waveguides and slot lines is a planar structure with more compact size and can be integrated with other planar microwave circuits, thus hopefully it has potential application in the near future..Based on the previous work of others, an improved parallel-line coupler structure based on composite right-hand/left-hand materials was proposed, some numerical simulations have been made and good performances have been demonstrated, but further work are still required.