Adaptive Sweep (ABS)
The Adaptive Sweep (ABS) is a type of frequency sweep which may be added as a frequency entry in a Sweep Set in the Sweeps page of the Circuit Settings dialog box. An ABS sweep is pictured below followed by definitions of the control fields.
An Adaptive sweep uses the Adaptive Band Synthesis (ABS) technique to perform a fine resolution analysis of a specified frequency band by analyzing at a small number of discrete frequencies then determining a rational polynomial fit to the S-parameter data to synthesize the rest of the response data. For a detailed discussion of Adaptive Band Synthesis, see the Adaptive Band Synthesis (ABS) chapter in the Sonnet User's Guide.
The output data consists of the discrete data points, frequencies at which the analysis engine, em, performs an electromagnetic analysis, and the adaptive data, which is data calculated using the rational polynomial.
Note: If you select None for the ABS caching level, and an ABS sweep is stopped before the adaptive data has been calculated, you will have to start the analysis over from the beginning. Any processing time invested in the analysis is lost.
If you only input a Start frequency or if the Start and Stop frequency are the same value, em will perform an analysis at that discrete point.
If you input a Start frequency of zero, then the response at DC is automatically calculated by extrapolating downward using the adaptive data.
The number of target frequencies provides the approximate desired number of data points for the defined band. The software divides your band into evenly spaced frequency points that provide as close to the number of your target frequencies as possible. The actual number of data points will vary slightly from your target. By default the number of target frequencies is 300 data points but you may also manually enter a value.
If you wish to set the number of target frequencies for an ABS analysis, click on the Settings icon 
to the right of the controls. The appearance of the entry changes to display a target frequencies input field, where you may input the desired number of target frequencies.
There are several things to be aware of when using the manual setting for the ABS resolution. Less target frequencies does not speed things up. Once a rational polynomial is found to "fit" the solution, calculating the adaptive data uses very little processing time. A really low number of target frequencies could produce bad results by not allowing the ABS algorithm to analyze at the needed discrete frequencies. A higher number of target frequencies does not slow down the analysis unless the number of frequency points in the band is above approximately 1000 - 3000 points. An entry of at least 50 points and less than 2000 points is recommended.