The Lange Microstrip (quadrature) coupler is known for it’s low loss, wide bandwidth and compact layout. Similar to other couplers, it consists of an isolated port, through port and coupled port.
You can build a microstrip Lange coupler using the DesignGuide tool in ADS:
These are the results for the equation-based simulation. These results admittedly look considerably better.
This is the substrate used:
These are the results for the momentum simulation. Admittedly, some tuning would improve this considerable.
And here is the layout component:
