hi

for the first check the geometries of the structure carefully and be relaxed in time! check the feed network and the accuracy of the solver.

thanx for the reply.

But can u please elaborate the points u want to say.

What kind of antenna are you designing and what are its specifications? Only then i will be able to answer your problem.

In my opinion most of researcher don't provide the exact specs of their research work in their papers that's might be the issue.....Meanwhile there are many other issues like depending on structure u  are simulating ,what type of port u have assigned what type of radiaiton boundary u have used etc

Dear Abhishek,

Please tell me specs of your MPA , i mean freq, geometry etc.. Is your model running , if yes what convergence are u getting in HFSS. how many adaptive passes have u considered ?? 

Two important points must be remembered in the design of MPA in HFSS. They are choosing of proper radiation boundary and convergence of the problem. Radiation box has to be properly substracted from the antenna model. If you are defining waveport then they should not be inside the radiation box instead it should be just touching the box. Material property also has to be selected properly. If you are not using metal plates with finite thickness don't forget to define perfect E boundary condition.

Thanks to all for your valuable answers.... further some of the research papers i find the wrong specification were printed.... but those were published in reputed journals but any why now i have taken a reference paper from ieee explorer and tried the geometry but the problem is same ...that is i dont get the results available in that paper.Ranajit dey  Sir this is for u ......

sir i'm using the wave port in my design and the radiation box size is equal to the substrate size ......sir i read some where that radiation box size is equal to the substrate size & its actually a cuboid which covers complete MPA .Im Correct or not. If not plz guide me sir

I'm mainly using wave port to which excitation is provided.

I'm providing prefect e boundary condition to patch ,ground .and rad to the radiation box.

my next question is that what should be the size of radiation box.

which port will be better for uwb range i.e for 3.1 to 10.6GHz.

In the last can u provide me ur contact detail ie.mobile no so that i can contact u in ur free slot.

I assure u ill dont disturb u in ur work.

For radiation boundary min distance should be lamda/4 from the simulating structure in all directions .

For patch antennas wave port is preferred however lump port can also be used depending upon the ground plane structure used either coplanar or conventional

In modelling in HFSS, I will recommend that you draw your 3-D structure in Solidworks or any CAD program and import it in HFSS. In my case SAT files work best. If u prefer to draw in HFSS then do it…(in my case it take lots of time to do it in HFSS)...

But before you set off….You have to bear in mind some of the points I am about to discuss in drawing your 3-D model…because all that I will mention below should be included already in your 3-D model drawing.....

You have to ensure that the dimensions of your 3-D-structure are correct and the scaling is what you want.

Then you go ahead to set the model conditions; Set the materials (copper etc..), ground plane (as perfect electric conductor), Air box as radiation etc etc.

If you will be using discrete elements for impedance matching, you go ahead and define them using LUMPED RLC elements in HFSS…you can set the capacitance, inductance and resistance….etc....

Then you go ahead and define your excitation port….(lumped or wave port ) both should be fine…

Now all these stuff...lumped elements, excitation should be in your 3-D structure already.....

If your antenna is electrically small (~λ/10 the operating wavelength), then HFSS uses the wheeler cap method in calculating your Far-field parameters (gain, efficiency etc etc) so the Air-boundary dimensions should be ~λ/4 the expected operating wavelength from all surfaces of your antenna…. or at least the surface with the expected maximum radiation (reception)…(I see others have already advised you on this already…)

Now you can go ahead and seed your meshing (or do manual meshing to be specific)…this ensures that the meshing is at most ~λ/10 the operating wavelength….this gives more accurate results…

Then you can go ahead and simulate your model and hopefully it will give you accurate results. I hope this these basic steps helps....There is so much one can do to improve a model in HFSS….but these simple steps can get you going…If you still need some example antenna models in HFSS...…I can send you some of the models I made for my studies..…

the reason you are not getting result is be careful about radiation boundary (greater than lamda/4), port defined and excitation and adaptive pass (keep it more than 10).

You must verify your radiation bounderies, and your sweep and convergence limits

Thanks for reply sir ......

Further i have kept the radiation box boundries lambda by four distance from eatch radiating edge.

Can u plz tell me how to check convergence in hfss for microstrip patch antenna.