two question for simulation!
1-why Momentum(ADS) works with an infinite ground plane? we can define a finite ground plane? fo see for example the wave diffraction at the edges of the ground plane, is not more accurate whenwe work with finite plane (its reality )?
2-I leads to simulate a circuit in momentum ads, and when I run the simulation, it stops and display the message
"Memory allocation faillure, no more virtual memory available"
I have 4GB of RAM and a 600GB hard disk , I add virtual memory, by multiplying the one of RAM 3 (4000MB * 3) (
by following the steps that windows 7 shows ) in two hard disk . and it is always the same result! or is exactly the problem? thank you in advance!
The advantage is that these infinite planes (=boundary conditions) are available "for free", without having to mesh a "drawn" ground plane. This is more efficient for memory and simulation time.
No problem, you can do that if you want. Modify your stackup, so that you have Freespace absorbing boundary at top and bottom instead of //GND//. Now, you must insert a metal layer in your stackup where you have your drawn, finite ground. That's all.
If you have a 32bit opertaing system, Momentum can only get 2GB of memory, no matter how much swap you define. You need a better machine with 64bit opertaing system, or simplify the mesh so that Momentum needs less memory.
thank you volker
1-So this question of infinite ground plane , it perfectly reflects the reality practice, we do not need do a finite ground ? since it is a question of simulation time and memory space!
2-for finite ground , thank u , its very easy! :)
3-i have 64bit system and 4G of RAM and core i3 processor , but when I installed (ADS momentum) in my pc, I had two file (. exe), one 32-bit and other 64-bit
I executed one of 32 (the 64 did not want to execute) , So, no matter what I like system (32 or 64) since I installed 32-bit ads, so I can not fully benefit from my RAM!
thank you volker , and please if you can respond to my questions one by one as you normally do!
If the physical ground plance is larger than the antenna (rule of thumb: patch size + 3 * substrate height on each side), the difference between finite and infinite ground is small. We only use drawn finite ground if the ground is very small and changes results, or if we need to know the "back side" antenna pattern.
If you run the 32bit program on a 64bit system, the 32bit program can use the theoretical maximum of 4GB RAM. So in your case, it can use the existing 4GB RAM size. To use more than 4GB RAM, you need to install the 64bit application.
You might notice that I mentioned a 2GB limit before. The possible address space for a 32bit program is 4GB. In 32bit Windows, only 2GB are available to your program, and the other 2GB are reserved for the Windows operating system. Running on 64bit Windows, each 32bit program can use the full 4GB that is theoretically possible. So in your case, 32bit ADS can use 4GB (but not more, even if you add swap space or more physical RAM)
thank you Dr.volker_muehlhaus.
for 3rd question , it is well understood!
2-for question about ground plan :
when I add a conducting plate as you said , it displays:
s-parameter results show unphysical behavior for certain frequency
cause:-inaccurate (high frequency) calibration
-electrically large via using lumped model
-high order modes at the ports
-slot mode at coplanar ports
-grouped strip-slots ports
-mesh desnity is too coarse
even though , i don't use (via ) and i don't use (coplanar port) , which means that these causes are only suggestions! but when
i add (ground reference port) in the ground plane reference the warning (s-parameter results show...) no longer displayed!
design:
http://images.elektroda.net/33_1340217562.jpg
1-how do you explain that? is that this has a physical sense ? what is the role of this port(ground port)!?
thank you
This makes physical sense. Every port needs signal node and reference (ground) node. If you have the infinite ground boundary condition, Momentum knows that this is the ground reference for your ports. But if you have a drawn ground, Momentum does not know what polygon is ground and what polygon is something else. In this case, place ground reference ports to tell Momentum that this is the ground reference for your ports.
Does this make sense?
thank you very much volker!
goof interpretation ! , and that's what I understood me!
so volker
1-finite or infinite ground plan , both support the propagation of waves in the substrate
2-dimensions of ground plan (finite) , this is my choice, and I accept the consequences , if i want to choice more than (patch size + 3 * substrate height on each side) there is no problem!?
3-if i work with (2)patchs antennas , and if i choice to work with the rule (patch size + 3 * substrate height on each side) , patch size in this case will be the size of two patch antennas! (normally evident!)
thnaks volker!