vivaldi antenna
I designed a Vivaldi antenna with taper rate of { exp(0.15*z) } in the 500-2500MHz frequency range on RO4003 substrate with Er=3.38 ( Fig.1). The simulation results (Fig.2 and Fig.3) that carried out with Ansoft HFSS V9.1 estimate very good performance (VSWR < 1.6:1 ). but when I construct this antenna and measured input VSWR of it, I saw that VSWR is greater that 3:1 ? (Fig.4 and Fig.5). I simulate this structure by assuming construction tolorances but simulation results didn't change. I beleave that port definition is wrong.
I upload my structure .sat file, Can anybody simulate this antenna with other softwares (CST or IE3D or ...)
Thanks in advance
KMPA
Hello,
I'm not sure as to how to help you because I'm just trying to figure out how to draw an exponential taper in hfss v9.1. How did you draw yours?
Thanks
Hi gregb3d,
I drowe y=f(x) in AutoCAD with a simple AutoLISP code and imported it to HFSS.
Here results calculated by MWS.
The energy has settled down to -40dB.
What port you used in physical realisation? Coaxial to strip transition?
Cheers
eirp
PS: I had to slightly modify the port region by adding small strip feeder. However this won't affect the results a lot.
PPS to gregb3d:
In MWS you can simply create analytical curves using VBA macros accessible from MWS GUI. I don't know if HFSS has also such tool, but it's very practical
Hi,
I'm simulating your .sat file now in hfss v9.1 and i'll let you know what i get. from my experience it's most likely a port definition problem.
Hello,
I'm quite sure it's NOT port definition problem.
In MWS the modal solver gives Z0~43Ohm and pure TEM wave as exists in stripline
rgz
eirp
Hi gregb3d,
find, please the attached AutoLisp file,
This file draw a vivaldi curve.
Regards
KMPA
Hello,
KMPA:
Below are the results I generated with your .sat file. The s11 results look exactly like yours. I used a waveport in the simulation.
eirp:
You may be right about the port not being the problem but I'm not sure what else could be wrong. Maybe the rad field is too small?
gregb3d
Hi eirp,
if it possible for you, please post here your simulation project of Vivaldi with MWS,
Thanks
KMPA
kmpa,
Have you tried running your simulation with metal of finite thickness?
gregb3d
Hi,
I used a 35 um thickness for all metals in vivaldi antenna and simulated it again with Ansoft HFSS V9, but VSWR curve didn't change. (jpeg is VSWR)
KMPA
Hi!
I have a new trial version of cst, can you send me the file.sat of the vivaldi antenna, so I can try to simulate that?
did you have the hfssv9.1 array model of your vivaldi antenna?i want to simulat it,but i don't know how to formulat the model of vivaldi antenna array?how about your?thanks!
From the *.SAT file:
1. the wave port did not touch both metal plate.
2. the radiation boundary box is not big enough compared with your wavelength.
Simulation is ongoing, I'll keep you updated. At least the part of the result from 0.5~0.8GHz I got is nice, and it is far from your simulation results.
Regards,
hi !
I have download your *.sat file and import it in the HFSS v9.0 ,I find that the positon of the top ground plate is not consistent with the sub.maybe that is the reason! I am a beginner of hfss,and i want to simulat vivaldi antenna array ,can you tell me the exictation and the boundary conditions of your example presented
here.From my simulation,the fields plotted on the antenna cannt travel by the way of slot line.can you tell me the reason?The port is wave port and the top and bottom boundary of the antanna is PerE,the right and left boundary is PerH. the wide side of slot line of the antenna is radiation boundary.
thanks
OK, the whole HFSS project file is attached, and part of the simulation results. I dont have enough time to simulate wide frequency bandwidth (even this part of results cost me more than 2 days simulation), but current results at least make sense comparing with the measurement results.
Regards,
S11, VSWR, and radiation pattern plot.
Regards,
Yes, the wave port in SAT file is not correctly set up.
About the boundary condition, please check my uploaded project file.
Regards,
Thanks a lot !
I have acquired that the wave port in HFSS should be enclosed by PerE boundary conditons,right?The simulation with HFSS needs lots of time. Maybe the simulation of antenna array is out of the question.
Another question about the AutoCAD :How to import the AutoCAD files into the active HFSS window?I have download your example (*.sat)and import it into AutoCAD ,the geometry is shown correct ly in the AutoCAD window.But when I carry out the similar process from AutoCAD file which is obtained by save your example as *.dwg file to HFSS 3D modeler,the error message is "you are importing an native body"! WHY?
Hi !
I want to see the fields distribution on the zone near the vivaldi antenna ,but I can plot the fields on the top and bottom ground plane ,can you help me?The fields dis tribution between the two slot lines can not be viewed?why?