bazza1988
Newbie level 3
Hello,
I have been trying to simulate a FG-CPW at frequencies in the mm-wave band 190-310 GHz, with the aim of determining the amount of radiation loss from the CPW transmission line. The dimensions of the CPW are w = 2 um, g = 1 um and wg = 3 um, on a 300 um thick Si substrate. The conductors are 2D sheets assigned with a PerfE boundary condition and the substrate is defined with \[\varepsilon\]R = 11.9 only (tan\[\delta\] = 0). I have a radiation boundary condition on all faces of the vacuum box, spaced \[\lambda\]/2 away from the transmission line.
I am currently using modal solution setup with a waveport (WP) excitation, but am having a bit of trouble exciting the structure. I have spent a bit of time searching forums and tutorials on how to excite a FG-CPW, but non of the recommendations are applicable. For example, the standard recommendation for the height of the WP is ~ 10*substrate height, which would result in a WP height of 3 mm, which is much greater than lambda/2. I have tried cutting 'fingers' in the WP to ensure that the two ground planes are at the same potential, and also simulated the first five modes to determine whether the correct CPW mode is being excited.
After taking all the advice and experimenting, I'm still unsure as to whether I am exciting the transmission line correctly, therefore if anyone has any advice, it would be greatly appreciated.
If there's any other information you need, let me know. I am able to upload my HFSS file if needed.
Cheers,
bazza1988
I have been trying to simulate a FG-CPW at frequencies in the mm-wave band 190-310 GHz, with the aim of determining the amount of radiation loss from the CPW transmission line. The dimensions of the CPW are w = 2 um, g = 1 um and wg = 3 um, on a 300 um thick Si substrate. The conductors are 2D sheets assigned with a PerfE boundary condition and the substrate is defined with \[\varepsilon\]R = 11.9 only (tan\[\delta\] = 0). I have a radiation boundary condition on all faces of the vacuum box, spaced \[\lambda\]/2 away from the transmission line.
I am currently using modal solution setup with a waveport (WP) excitation, but am having a bit of trouble exciting the structure. I have spent a bit of time searching forums and tutorials on how to excite a FG-CPW, but non of the recommendations are applicable. For example, the standard recommendation for the height of the WP is ~ 10*substrate height, which would result in a WP height of 3 mm, which is much greater than lambda/2. I have tried cutting 'fingers' in the WP to ensure that the two ground planes are at the same potential, and also simulated the first five modes to determine whether the correct CPW mode is being excited.
After taking all the advice and experimenting, I'm still unsure as to whether I am exciting the transmission line correctly, therefore if anyone has any advice, it would be greatly appreciated.
If there's any other information you need, let me know. I am able to upload my HFSS file if needed.
Cheers,
bazza1988
