Which one is better， HFSS or CST ?

Does anyone can give a comment on this topic?
Which is one is better. I've experience in H F S S and found that it is pretty slow and memory hungury. For a circuit with two plannar inductors, it takes on more than 1GB memory. Does CST offer anything better?

I have found CST to be easy to use, accurate and fast.
I use it to design coaxial components and antennas, if I'm carefull I normaly achieve about 1 percent maximum error between the built prototype and CST model.
The optimisation system is easy to use and saves me lots of time in developement projects.
I tried all the others, but after using CST I haven't looked back.
I don't work for them.

I stand by your point.

In my opinion, MWS is one of the best EM simulators. I've tried more, but now I'm using MWS and IE3D. MWS is unique due to PBA meshing which save a lot of time and gives accuracy. Another fact, MWS is very user friendly! I can recommend you it.
Eirp

eirp's point is absolutely correct. I used hfss and mws designing a cell phone antenna. Hfss took 4 times in time than mws. Some complex problems may widen the gap. Like eirp said, to use more friendly is what an enigneer needs especially to new guy in terms of RF aspect.

Hi
All above correct but if you need a printed
antenna you can draw it in IE3D. run it for
optimum results, then import by MWS and
run the last one for acureccy.
RGZ ZXC

Maybe we should start a C/S/T usergroup?
It would be good to share experience, macros and more.
What do yo think?

It's a good idea (maybe it can cover not only C/S/T but EM simulators as general). I think there's a lot of people using it, with good knowledge and experiences.. They helped me to solved some of problems in my projects time ago
If we speak about C/S/T, I'd like to say that it's becoming a standart in companies.
Eirp

This thread demonstrates a positive side of elektroda!

Is there a negative side?

Well, let me throw my 20 cents inhere. To my opinion both SW are complementing each other. I still prefer the HFSS for they implement many physics and microwave features and not only the GUY. Quite frankly, CST GUY is not even theirs - they have this licensed to them by Dassault spin-off that every one can get today. Interested folk can pm me if they want to know the URL. Next to it: if one reads carefully the CST manual it says that the 'wideband' accuracy is in fact not so high and for truly large badwidth one must resort to splitting the band in parts. Third - CST folks is really smart in a way - they saw the HUGE deficiency the time-tomain solver exhibits and veeeeery quickly implemented the frequency domain solver - feature that most of the engineers highly praise for both speed and accuracy and one that resembles the HFSS one:):) I still wander what CST folks has to say about it:). Next to it, the default settings of CST are too poor for any decent structure. One has to tune the meshing quite fine and some other advanced FDTD specific techniques. Time domain solvers generally exhibit some stability issues to handle - please pay attention that FDTD DOES NOT use the acclaimed FIT (Finite Integration Technique)in MWS but only in MAFIA. Simply said, the unstructured grid is difficult to handle in terms of stability etc. It is a rather long topic to discuss in here.
HFSS - rock solid core, great meshing with best possible manual meshing flexibility, MANY advanced features like Master-Slave BNDs, Freq-dependent materials, ferrite devices easy to do, superior antenna simulations, phase array is like a pleasure doing, etc. great flexibility in applying boundaries one over the other with clear order. Many more ports and boundaries -
Cons: we all know about the shitty and ugly interface - Ansoft folks is heavily working on it - and my information is that their interface will be far superior. One other thing to consider - for heavy WG structures - CST is desperately inaccurate and slow - especially for resonant structures, but not only. Price to pay with CST is finer mesh and looonger time.
So, my opinion is that the 2 solvers compliment each other for various applications - CST is definitely more user friendly and 'colorful', while HFSS is more 'professional solver' of the old time when every one was working under DOS like (or rather Unix) style. CST has its own merits but if I have to send a structure to the CNC machine I'd rather put in scrutiny with both - HFSS being the last one and compare. In terms of accuracy - I'd rather stick to HFSS, while speedier award is granted to CST.
Hope it helps. I very much praise the idea to have eaither CST MWS or HFSS (or both:)) forums in here.
greetz,
P.S About IE3D - speedy Gonsalez but lacks accuracy - Zeland is claiming accuracy is not their biggest concern (private talks with them) but rather being able to simulate 'larger' structures. It is why no one uses IE3D to design MMICs for instance. Losses in IE3D are incomparably poorer than Sonnet or Momentum - Again, best user interface and other 'cosmetics' in it - for patchy antennas be aware of about 5% freq shift downwards whatever you do in the setup. That's all for now.
Wish everyone Happy New Year.

Somebody should mention that MWS's eigenmode solver does not allow materials to be specified, whereas HFSS's does.
/Dan

It would be great if we could take a few geometries and each of us would analyze them on their own machine/soft.
Generating a significant data base for references would increase/decrease the confidence in the software.
I am an antenna guy and I already lost money manufacturing something that was not properly predicted.
I'm really pissed and now I work like 30 years ago: manufacture step by step and TEST!
If your money is at stake, you could be in trouble trusting the 50K MWS or others.
There is a paper (u can find it at
http://www.anteg.net/tuli/paperspdf/...TLAKE-2000.pdf) which makes a timid atempt to just do that, but there are not many details. for a start, we could just take those examples.
If interested pm-me

Every software has it's merit,So HFSSvsCST is not a simple compare.

I have already done a lot of C/S/T/realworld comparisons and found the accuracy to be good for return/insertion loss in coaxial components and antenna radiation patterns.
However, I can't really give any of you drawings of the items compared for legal reasons (and someone could work out who I am).
I'll have a look around our workshops over the next couple of weeks and see if I can find a few simple items to compare. I can then post both sets of results and some simple drawings onto this forum.
If someone could then run the same models on H/F/S/S we can do a comparison.
I think a resonator, coaxial transformer and a dual dipole array should be good enough.
Let me know if you think I should do more.

Radiation patterns should not be a problem in simulations.
The impedance IS.
I am working on microstrip arrays, where the knowledge of the input impedance is critical before the design of the feed network.
This is important especially in the design of low sidelobe arrays.
Even more critical for the design of serial fed arrays.

Gakusei I will run the HFSS simulations if you post the required models. I've been using this program extensivelly in the last while, and only recently have been thinking of moving to MWS. However my first experience with MWS has been quite bad (I was probably doing something wrong).
Anyway, we definitely should get some sets of comparisons of the two EM simulators -- the sooner the better.
Regards,
/Dan

kato01
Actualy the problem of antenna self/mutual impedance and distribution system design is a circular one which I have lost much sleep over in past years. Just changing the distribution cable lengths in an array can have a profound effect on the radiation pattern and impedance if the mutual coupling is high.
I think the best thing to do would be to model a dual dipole array which is serialy fed (I presume this is what I call a traveling wave feed system) and include the feed system in the model.

Guys, let's start the match, please!
I'm waiting for your results too, it can be very interesting for us!
I prefer to make some simulations which is measured in literature also, so we can compare it absolutively with measurement.
What about a Yagi antenna? It's very similar to what Gakusei noted about dipole arrays and we can found measured results both for impedance and radiation pattern.
Best regards,
Eirp
PS: You can read this article too:
http://www.mwee.com/magazine/2000/CAD_nov.htm
There is discussed Vivaldi antenna simulated by H/F/S/S,M/W/S and E/M/P/I/R/E

Gakusei,
Yes, you are right about cables and stuff, but I was refering to microstrip antennas where the rasdiating elements and the feeding distribution network are printed on the same surface.
EIRP,
The article in Microwave Engineering just shows how little these programs can be trusted.
For simulation (since we already have results), I suggest the structures described in
http://www.anteg.net/tuli/paperspdf/...TLAKE-2000.pdf
any takers?
I can do IE3D. I'd love to do MOMENTUM but I donm't have it