Novice to Ansoft HFSS needs help urgently!!

[frequency999]

Hi ppl.....

I am using the ansoft hfss v 10.1, I am totally new to this software and i need help and clarity on the following issues:

1. Excitations: i have seen the list of excitations, but could not get when to use which excitation. what does it mean by lumped port excitation.... specifically if i want to give current to a pcb track that is solid strip how do i give excitation...

2. Boundaries: there are various boundaries available, in the software but could not determine when to use what....

3. How do we decide a particular solution frequency for eigenmode and driven mode also....

4. if we are defining an infinite ground plane why do we have e-field on the ground plane...in my view there shouldnt be any field on the ground plane as the surface will be an equipotential.

It would really helpful if u could address my concerns as I am an amateur in this area....

hoping help,
Frequency999

 

[tallface65]

There is a help guide in the tool and all of your questions can be learned by going through the tutorials...also, the latest version is HFSS13, I strongly suggest you upgrade as 10.1 is nearly 5 years old!

 

[frequency999]

Thankyou tallface65, for giving a good advice...but my observation goes like this...in the help guide the issues are addressed mostly on "how to" rather than "why to"... precisely i want help on this....

 

[roxxon]

1. The most important excitations are the waveport and the lumped port, and in my experience the second is even more important - but the solutions are/can be slightly less accurate. The waveport is actually a 2D eigenmode solver itself, so it finds (or tries to find) the correct excitation modes to apply. It can be used only on (perfect) conducting surfaces and bodies or on the outside of your model, where you apply radiation boundary or PerfE.

A good tutorial using the waveport is: em: talk - HFSS Tutorial 1: Microstrip Patch Antenna

Normally, especially inside the model and for balanced excitation you use the lumped port. With that, you will have to define the port impedance yourself.

I also commonly use a coaxial stub (like a coaxial connector) which I build myself (I am sure you can figure that out yourself) using a waveport.

2. The most important boundaries are the radiation boundary (on the outside box of your model, if you model an antenna), the PerfE (perfect electric conductor) e.g. for simplified 2D structures etc, and the PerfH (perfect magnetic conductor), which can be used quite similar. Note that, if you don't apply any boundary on the outermost box or structure, HFSS applies PerfE automatically.

3. For the eigenmode solver you cant "decide" on a solution frequency, you can only choose the minimum mode frequency and the number of modes HFSS should find. For the driven mode, of course the solution frequency should be the one you want in the end, or, if you're looking for a frequency band, it sould be the uppermost frequency (fast sweep and discrete sweep) or the center frequency (interpolating sweep) - although it does not matter that much, normally (unless your doing UWB or something like that).

4. Note that on even on a perfect conductor, only the tangential electric field has to vanish, but not the normal components!