how do i mdel a waveguide in HFSS?

[Athina]

rg213 model hfss

Hello.
Perhaps someone could help me, at least guide me into which tutorial to look at.. :/


I have designed a small patch antenna, with a resonance frequency of approximately 6.5Ghz. I cannot change its dimensions, since this is the largest antenna i am allowed to use in my application [it is a square 4cmx4cm antenna]. However, the antenna needs to have a resonace frequency around 3Ghz.

Thus, i need an adaptive circuit after the antenna (and before the rest of the electronics). The antenna is fed by a simple SMA for the time being. So, in order to model it in HFSS, i need to add a T. The one port is connected to the initial SMA, the second is where my feed is going to be, and in the third i should put an adjustable waveguide, followed by an open-circuit ( I think.. Am i correct in this???:?.

I have designed the T, but i have no clue on how to model the waveguide and/or the open-circuit.

Could anyone help me regarding the dielectric properties or the specific hfss components I should use?
Or even if there's an online manual about this, it will be really appreciated.

Thank you all in advance

 

[PanosB_GR]

Hello Athina,

I guess you have to just model a simple open-circuit coaxial line, and its variable length would give you insight on any resonances that might shift down the matching to lower frequencies.

Coaxial cables have standard dimensions (for example the rg-213) and are almost all filled with teflon as dielectric (er=2.1). The dimensions of the inner and outer conductors can be easily found from any cable manufacturer.

Waveguides have also standard dimensions (WR-xx), but a matching network with a coax would be more appropriate for realization.

Regards,

P.

Added after 20 minutes:

The thing is though, that even if you do a good matching of your antenna by using coaxial lines, the gain at 3Ghz might still not be adequate enough for your application.

And, by the way, a bench-top tryout of coaxial lines and open circuits might just be a lot quicker and more fun