phased.LinearFMWaveform is a baseband implementation by design for efficiency. The 'frequency offset' is used to modify the sweeping frequency band. Theoretically, it may be used to simulate a passband signal; but you need to have a very large sampling frequency and large offset.
One efficient way for implementing carrier is to use phased.LinearFMWaveform for baseband signal generation, and then implement a modulator in a seperate object. (there are system object for modulation).
