[SOLVED] Need help designing an aperturecoupling

[Ente]

Hello,

i am doing some simulations on microstriplines and i have a Problem. when i simulate the microstriplines with 2 ports i have a good s11 and s12. when i take out the 2nd port my s11 goes terrible. I think its because my microstripline is not terminated with anything. i am doing this because i want my microstripline to be coupled with an aparture. so i am terminating my microstripline with an 0.35mm Via to the ground plane but my S11 stays terrible. what am i doing wrong?

 

[FvM]

i want my microstripline to be coupled with an aperture

Please show the geometry

 

[Ente]

Please show the geometry

unfortuanally i cant show the entire thing but here is an example on how it should look. the aperture couples on another thing where i want to get the S12 from. but my S11 is terrible and i dont know how to fix it.

 

[vfone]

You are trying to feed a slot antenna using an open microstrip line, which is a normal situation.
To get good S11 the open line needs to be shorter, stopped just after crosing the slot.
The microstrip length and the slot width, BOTH need to be adjusted for best S11 at the frequency of interest.
If need the feed-line to be longer, after crossing the slot, this must be terminated.

https://d3i71xaburhd42.cloudfront.net/6a7abaa74758ad3f85cbb47a25e15353d91dbe60/2-Figure1-1.png

 

[Ente]

You are trying to feed a slot antenna using an open microstrip line, which is a normal situation.
To get good S11 the open line needs to be shorter, stopped just after crosing the slot.
The microstrip length and the slot width, BOTH need to be adjusted for best S11 at the frequency of interest.
If need the feed-line to be longer, after crossing the slot, this must be terminated.

https://d3i71xaburhd42.cloudfront.net/6a7abaa74758ad3f85cbb47a25e15353d91dbe60/2-Figure1-1.png

Hello, first of all thanks for the Help.
I can choose slot position freely. Length and width of the substrate too. Most of the time i tried to get good results with the slot beeing exactly in the midle for maximum symetry. Does the slot being at the far end have something to do with the wavestate at the end of the MSL?

I designed the MSL using the Msl calculator from emtalk. but i am a bit lost how to design the slot width. currently i am in a state of trial and error. is there a convention lage lambda/4 for the slotwidth?

 

[vfone]

MSL calculator from emtalk should be fine.
Here you can find the equation for the slot width, but the width could be further optimized for your feed-line:

https://www.ijitee.org/wp-content/uploads/papers/v8i2s/BS2668128218.pdf

 

[Ente]

MSL calculator from emtalk should be fine.
Here you can find the equation for the slot width, but the width could be further optimized for your feed-line:

https://www.ijitee.org/wp-content/uploads/papers/v8i2s/BS2668128218.pdf

Hello i did some simulations but my results are staying terrible. I dont know if a slot antenna is the right way for my project. I am trying to model a aperturecoupling of 2 microstriplines that have an aperture in their groundplane to couple the signal from one stripline into the other if you put the 2 appertures near each other.
Important is the S12 and the S11. have you some design experience with anything like this?

 

[Ente]

Hello, i have done some studies about aperture coupling and for a project i have to simulate a coupling method from 1-2GHz with good S11 and S12.

I have done small analysis to microstriplines and their S11 as well as aperture coupling. To get good S11 with a open microstripline i created a via at the end to have a short circuit from the via to the ground plane. i did some simulation for the aperture size and position but all the results i got were super bad. The signal gets coupled from the bottom port (far up in the picture) to the top parrt so i moved the via more in direction bottom end of stripline. Currently i am running a lot of trial and error simulations but i feel like this cant be the way!

Does anyone has experience designing an apperturecoupling and can help me with some parameters?

Best regards.