The AWE method is very useful when simulating resonant circuits, especially single-resonance bandpass-filter type devices with many frequency points. When using the Adaptive Frequency Sweep study, the simulation time with a much finer frequency resolution can be almost the same as a coarse resolution regular Frequency Domain simulation.

The simulation time may vary depending on the user input for the AWE expressions. Any model variable works as an AWE expression, so long as it has a smooth curve shape like a Gaussian pulse as a function of frequency. The absolute value of S21, abs(comp1.ewfd.S21), often works as the input for the AWE expression in the case of two-port bandpass filters. For one-port devices like antennas, the absolute value of S11 is a good choice. If the frequency response of the AWE expression contains an infinite gradient — the case for the S11 value of an antenna with excellent impedance matching at a single frequency point — the simulation will take longer to complete because it requires many data points to describe the sharp dip. When the loss in a one-port device is negligible, an alternative expression such as sqrt(1-abs(comp1.ewfd.S11)^2) may work more efficiently than using abs(comp1.ewfd.S11) directly.

With a very fine frequency step simulation, the solutions contain a lot of data. As a result, the model file size will increase tremendously when it is saved. By selecting the Store fields in output check box in the Values of Dependent Variables section of the Frequency Domain study step settings, it is possible to define for what part of the model the computed solution should be saved. When only S-parameters are of interest, it is not necessary to store all of the field solutions. Instead, only store the field on the selections for the port boundaries, as those will be used for the S-parameter calculations.

In the Values of Dependent Variables section, change the selection in the Store fields in output combo box from All to For selections and then add the explicit selections that include the port boundaries. The explicit selection can be easily created from the port feature by clicking Create Selection icon in the Boundary Selection settings once the selection is specified.

The solver performs fast adaptive frequency sweeping using an AWE method. To trigger the AWE in a Frequency Domain study, the following steps are required: