Rectangular dielectric waveguide
时间：04-01
整理：3721RD
点击：
Hi, I am working on using a Rectangular dielectric waveguide(RDWG of dimension 7.112mm X 3.556mm ie Ka band 26.5-40Ghz) in some dielectric measurement.
I am at this point trying to simulate the behaviour of an unshielded RDWG only using HFSS. The first problem I have is that the simulations tell me that higher order modes are excited from 29Ghz which is contrary to what the theory suggest using effective refrative index, kumars perturbation method, marcartilli etc.
Also simulations tell me the dominant E11y will has a cutoff which is contrary to theory that it will propagate from 0 frequencies.
The method I have used are:
1. I draw the PTFE RDWG and cover with a airbox alone but HFSS treats the airbox( up to 3 times bigger than the RDWG dimensions) as a metal wavegude loaded with a dielectric (PTFE) and so I get wrong results.
2. Also I made the airbox a radiative boundary but the s21 is in order of -15db for a very small length of RDWG.
3. I have put 6 rectangular planes around the RDWG and assign them perfect E and this seem to give good result ie s12 less than -1db, s11 greater than -20db but collegues say this is wrong as I did not define the space between the RDWG and planes.
Can anyone help. Thanks
I am at this point trying to simulate the behaviour of an unshielded RDWG only using HFSS. The first problem I have is that the simulations tell me that higher order modes are excited from 29Ghz which is contrary to what the theory suggest using effective refrative index, kumars perturbation method, marcartilli etc.
Also simulations tell me the dominant E11y will has a cutoff which is contrary to theory that it will propagate from 0 frequencies.
The method I have used are:
1. I draw the PTFE RDWG and cover with a airbox alone but HFSS treats the airbox( up to 3 times bigger than the RDWG dimensions) as a metal wavegude loaded with a dielectric (PTFE) and so I get wrong results.
2. Also I made the airbox a radiative boundary but the s21 is in order of -15db for a very small length of RDWG.
3. I have put 6 rectangular planes around the RDWG and assign them perfect E and this seem to give good result ie s12 less than -1db, s11 greater than -20db but collegues say this is wrong as I did not define the space between the RDWG and planes.
Can anyone help. Thanks