HFSS hybrid coupler design

[Alphatosh]

hybrid coupler design

I am new to using HFSS, and have recently been trying to create a 90 degree branchline hybrid coupler. I want to eventually combine a bunch of these to make a Butler Matrix. I have designed it in ADS for 3 GHz, and got the results I was looking for there, but when I run it in HFSS, my plot still looks like a coupler, but not with as good of results. The substrate I am using has dielectric 10.5, and thickness 25 mil

I have included my design of the coupler.. if someone could take a look at it and possibly give me some insight that would be much appreciated. All of my lengths and widths are in terms of variables so that they aren't hard to change around if need be.

 

[YoungEng]

branch line coupler design hfss

Hello there aplhatosh,

It is good that you parameterized your circuit dimensions because tuning is usually required to get the best performance out of your design. I took a look at your HFSS file and thought that you might want to add 50 ohm microstrip lines at the ports of your coupler. This will help later on when you want to build the coupler and solder sma connectors to your circuit.

You may also want to try to use waveports instead of lumped ports, check hfss tutorials for info on sizing waveports for microstrip lines. This will require you to place the sides of your airbox in the same plane as the waveports. You might also want to try to apply a radiation boundary to your airbox instead of having it covered with metal (which is the default operation).