Coupler HFSS, with 90 degree bends

[alffnot]

coupler hfss

I am trying to simulate in HFSS a microstrip coupler, but it has 90 degree bends as the feed point. see attached picture. I have simulated alot of couplers before, but they have always had feed points on the same side of the substrate so I would normally use a wave port. but with the 90 degree bends I figure a lumped port would work becuase there isn't coupling at the ports becuase they are far apart. But with the lumped ports i keep running into an error, it tells me that the T-matrix is very close to unity and doesn't solve it. if i set the solution type to be driven modal instead of terminal it will at least solve but it is definiatly not the right solution, S21 come out to be around -200dB and S11 is nearly 0. I have simulated the same structure without the 90 degree bends and it works just fine

 

[id_guy]

design bends hfss

Are you chinese

 

[alffnot]

nope, is my english that bad?

 

[asdfaaa]

I am trying to simulate in HFSS a microstrip coupler, but it has 90 degree bends as the feed point. see attached picture. I have simulated alot of couplers before, but they have always had feed points on the same side of the substrate so I would normally use a wave port. but with the 90 degree bends I figure a lumped port would work becuase there isn't coupling at the ports becuase they are far apart. But with the lumped ports i keep running into an error, it tells me that the T-matrix is very close to unity and doesn't solve it. if i set the solution type to be driven modal instead of terminal it will at least solve but it is definiatly not the right solution, S21 come out to be around -200dB and S11 is nearly 0. I have simulated the same structure without the 90 degree bends and it works just fine

Your lumped port is not correctly set up. Try to reduce the size of the rectangle which is assigned to lumped port. During simulation, this rectangle is treated as PEC object.

Regards,

 

[alffnot]

I am trying to simulate in HFSS a microstrip coupler, but it has 90 degree bends as the feed point. see attached picture. I have simulated alot of couplers before, but they have always had feed points on the same side of the substrate so I would normally use a wave port. but with the 90 degree bends I figure a lumped port would work becuase there isn't coupling at the ports becuase they are far apart. But with the lumped ports i keep running into an error, it tells me that the T-matrix is very close to unity and doesn't solve it. if i set the solution type to be driven modal instead of terminal it will at least solve but it is definiatly not the right solution, S21 come out to be around -200dB and S11 is nearly 0. I have simulated the same structure without the 90 degree bends and it works just fine

Your lumped port is not correctly set up. Try to reduce the size of the rectangle which is assigned to lumped port. During simulation, this rectangle is treated as PEC object.

Regards,

how small should i make it, i thought i would want it to extend the total width of the microstrip and all the way to the ground plane. If it is treated as a PEC I don't understand how I would draw it at all. forgive me I have always used wave ports so lumped ports are new to me. I think i remember reading the HFSS tutorial on ports and them having a microstrip excited with a lumped port drawn as how i did. I could just be remembering incorrectly, i'll have to dig up that tutorial again. thanks for the help

Edit: oh yeah, and i did simulate by assigning a wave port to instead of lumped ports and i got a result as i would expect, so it must just be my port definitions as you said.

 

[asdfaaa]

wish this plot is helpful.

Regards,

 

[alffnot]

ok thanks, i'll give that a try, thanks again for the help