Will Agilent please implement an option in the substrate definitions of ADS-Momentum that allows users to specify a surface reactance in addition to surface impedance? This would be very useful for modeling superconducting films (where the kinetic inductance effect is relevant). Currently, we can only supply a surface impedance or conductivity, and so only works over a narrow bandwidth.
Rf/Microwave superconducting circuits are important for sensors going in numerous DOE and NASA projects and are becoming increasingly important for remote sensing applications funded through DOD and DARPA. There's also a large quantum information research community funded through defense grants that need to model superconducting effects as well for the low-temp transmission lines between SQUIDS.
This should be a very easy addition and the government contracts associated with this research should provide ample financial motivation for this upgrade. Currently, Sonnet and IE3D can simulate with surface inductance, so you guys have lost some market share to them despite your product being superior in most other ways.
Rf/Microwave superconducting circuits are important for sensors going in numerous DOE and NASA projects and are becoming increasingly important for remote sensing applications funded through DOD and DARPA. There's also a large quantum information research community funded through defense grants that need to model superconducting effects as well for the low-temp transmission lines between SQUIDS.
This should be a very easy addition and the government contracts associated with this research should provide ample financial motivation for this upgrade. Currently, Sonnet and IE3D can simulate with surface inductance, so you guys have lost some market share to them despite your product being superior in most other ways.
However, superconductors have an surface impedance of Z=\mu_o \lambda \omega (aka kinetic inductance), where \omega is the angular frequency. In normal metals, the surface impedance is dominated by the term containing conductivity and this term's frequency dependence is hence unimportant. For those problems, Momentum works just fine. But for superconductors, this kinetic inductance cannot be ignored in the design of microstrips and other electronics since there is not resistive term anymore. For example, check out the ALMA memo on the topic:
www.alma.nrao.edu/memos/html-memos/alma245/memo245.pdf -
With Momentum's current substrate editor design, kinetic inductance can be implemented only over a narrow bandwidth when specifying the surface impedance or conductivity as you suggest. But for broadband applications, different simulations would need to be run for different frequency ranges to manually adjust this.
This class of problems could easily be accommodated if the substrate editor allowed users to specify a surface inductance per square, as allowed in Sonnet for example. Unfortunately, Sonnet does a poor job at simulating antennas thanks to their odd boundary conditions and we require simulations that model both the microstrip lines and the antenna simultaneously.
I'm agitating for Agilent to implement this because it's an easier fix than Sonnet modifying the details of their MOM algorithm.