Waveguide with a dielectic slab

[newRF1]

Hey guys,

I have this simple rectangular waveguide, with a slab of dielectric inside it. Inside the dielectric slab, if I have a metal sheet (not in contact with the top of bottom metal walls of the waveguide). Would effect would the sheet have on the waveguide's performance and why? Will it have any effect at all since the metal sheet is not touching the waveguide directly?
I tried simulating in hfss but i see that it gives me a S21 of -2dB in the operating band.

Could someone comment on this please?

 

[volker@muehlhaus]

Would effect would the sheet have on the waveguide's performance and why? Will it have any effect at all since the metal sheet is not touching the waveguide directly?

If it is parallel to the electric field (equipotential) lines, it should not have any effect. If it is perpendical, it will short/distort the electric field in that area.

 

[newRF1]

If it is parallel to the electric field (equipotential) lines, it should not have any effect. If it is perpendical, it will short/distort the electric field in that area.

Thanks for the reply.

If it runs vertical, i.e. along the height of the waveguide, i guess its perpendicular. But will it be shorting the fields if the metal plate is not touching the top or the bottom conductive plates of the waveguide. It's just suspended in a piece of dielectric, with no physical contact to the waveguide metals directly.

 

[volker@muehlhaus]

If it runs vertical, i.e. along the height of the waveguide, i guess its perpendicular.

Waveguide TE01 mode (from https://web.mit.edu/6.013_book/www/chapter13/13.4.html )


If you place a metal sheet in vertical direction, it will force tangential E field to zero and distort the field.

But will it be shorting the fields if the metal plate is not touching the top or the bottom conductive plates of the waveguide. It's just suspended in a piece of dielectric, with no physical contact to the waveguide metals directly.

I understand that, but the otherwise continuous E field in the waveguide must change to fullfill the E_tangential=0 condition at the metal sheet.

 

[newRF1]

I simulated, i would like to share the results, but i dont know why its not uploading my file in any way i tried.
When I simulate the metal sheet suspended in the waveguide, S21 is still near 0dB :S but if i make the sheet touch the top and bottom plates, then it drops.