designing a suspended-microstrip patch antenna in Ansoft

Ansoft designer

Pls. help on designing patch antenna. when i placed air beetwen ground plane and dielectric, and give elevation, should i draw rectangle on ground? Or the same question is for without air layer should i draw rectangle on ground plane?
What is the differences for drawing with or without rectangle on ground plane?

Thx for all.

Re: Ansoft designer

Hi,
are you trying to design a suspended-microstrip patch antenna? I guess that 'cause you are placing air between dielectric and ground plane. Anyway, the correct stackup layer is (from higher to lower layers):

signal---->trace
dielectric-->...
(air???-->for suspended-microstrip structures)
melallized signal--->ground plane

You don't have to draw any rectangle on ground plane because Designer sets an infinitely extended ground plane as default. Infinitely wide dielectrics layers (along the x-y directions) are set as default as well. You just have to draw the patch antenna and the feeding circuitry on the signal layer.
Free space and absorbing boundary conditions above the microstrip patch structure are set as default.

Designing a rectangle on a ground plane/metallized signal is like drawing an aperture/slot on an infinite metal plane. So, if you draw that reatangle, you are actually designing a 'void' rectangle and not a metal rectangular sheet. This concept may be useful for designing CPW structures and slot antennas in Ansoft Designer.

Hope this helps.

Re: Ansoft designer

yes thank you. i want to draw a suspended-microstrip structure. but when i prototyping, results are becoming meaningless as to designer.. So i wondered to draw on ground layer or not. i think my prototyping is poor, or i have to use HFSS..

Re: Ansoft designer

Designer is not suitable for suspended microstrips or suspended striplines. The problem is due to 2D basis function used during the discretization in MoM. As consequence, Designer doesn't have the concept of three-dimensional currents. As the port gets farther from the ground plane and this distance is comparable or higher than wavelength, the solution starts to decrease in accuracy.
I use HFSS for suspended structures. FEM is more accurate for 3D structures than MoM. Just be careful about the choice of the feeding waveport and boundaries to be applied. Should you need some directions for doing that, just let me know.

Bye.

Re: Ansoft designer

Ivan_ said:

Designer is not suitable for suspended microstrips or suspended striplines. The problem is due to 2D basis function used during the discretization in MoM. As consequence, Designer doesn't have the concept of three-dimensional currents. As the port gets farther from the ground plane and this distance is comparable or higher than wavelength, the solution starts to decrease in accuracy.
I use HFSS for suspended structures. FEM is more accurate for 3D structures than MoM. Just be careful about the choice of the feeding waveport and boundaries to be applied. Should you need some directions for doing that, just let me know.

Bye.

Click to expand...

Hello Ivan_


I am having some problem in designing suspended microstrip feed patch antenna. Can u please send me some example simulation file to learn how to do that.

PLz .....