Please help with HFSS dipole antenna

Hello.
Can you please help with design of this antenna in HFSS 9.1 (see file). It works on frequencies about 1 Ghz. Which antennas like this are used by people? I need to get normal radiation pattern and S11 parameter. I use waveport. How can I optimize these parameters as function of antenna height? When I click project variables -> local there is some strangeness with units. And I get S11 ~= 0 db! It's wrong!
How antenna's screen actions upon radiation pattern? I don't want that antenna radiate downward.

I now don't remember my reg. number or something else, but please help, because my question is simple and small, and if I will not get answer I have to use another program.

Thanks. Ivan

these antennas are generally used in cell phones (around 1GHz)

you need to send us the file, no file is attached to your message.

Please see this! How can I do normal antenna and where I can read about it? How screen is influences on pattern and S11? How I can see pattern vs different radiuses of screen?

Hi motorway,

Have you found the answer yet ?
Please share with us your updated .hfss file (or you can send to my email :)
I think you should use project variable (Srd) instead of local variable (rd).
How? select in menu: project/project variable.

Dear motorway,

I'd a quick scan through your structure, so I'll just give a few opinions.

Is that a monopole or a dipole you're simulating? Cos' the hfSS structure looks like a quartered-up (you're making use of the image planes, right?) coax-fed monopole with curvy ground plain.

So, with respect to a pretty decent monopole simulation in HFSS, I think there are a few changes to be made:

(1) You don't have to use image-planes. It's a simple structure, you don't have to complicate your simulation results for that. :) Besides, I think you gotta do some post-processing (e.g. multiply the simulated impedance results for the final one) if you use the image-thingy.

(2) You don't have to have such a long coax-feed. Roughly the same height as your coax dielectric's diameter will do. This was suggested to me by HFSS engineers.

(3) I think you need larger air-box/radiation boundaries. Your radiation boundaries should be at least 0.25 wavelengths (or more) to the tip(s) of your radiating element.

Hope these helps,
Dave