You can model the following components of a radar transmitter:
Specs
Frequency/Wavelength. Select Wavelength or Frequency and enter the desired value. This option is available only for a Monostatic operation. For a Bistatic operation, frequency/wavelength is determined by the other radar serving as the bistatic transmitter.
Power. This is the peak output power of the transmitter. It is available only for a Monostatic operation. For a Bistatic operation, peak power is determined by the other radar serving as the bistatic transmitter. It defaults to 40 dBW.
RF Filter
You can enable power spectral density (PSD) analysis and/or RF spectrum filters on the radar object.
Radar objects use signal power spectral density analysis to compute the reflected signal power as seen by the radar receiver's front-end bandwidth.
The fidelity of the radar system analysis is enhanced by taking into account the signal spectrum and the distribution of power across the frequency band.
The transmit side filter of the RF spectrum allows the radar's power spectrum to be shaped to conform to a specified power distribution.
Starting with STK 10.1, the radar model places the transmitter side RF filter after the power amplifier stage. This implies that the filter’s characteristics response will update the transmitted signal PSD and the final signal bandwidth is the RF bandwidth of the transmitted signal. Also the RF filter insertion loss will attenuate the RF output power of the radar system.
Power Amplifier. User-specified default value for the radar-transmitted signal bandwidth. A uniform power spectral density model is used for the signal power spread across the bandwidth. This signal bandwidth value is used to compute the amount of signal power seen across the receiver bandwidth.
The use of a transmit-side RF filter determines the signal spectrum shape and the bandwidth. The transmitter filter bandwidth will (internally) override the Power Amp Bandwidth value. In the case where the transmitter RF filter is not used and Enable PSD Analysis is selected, it computes the unconstrained signal spectrum to ± 15 nulls, and the signal bandwidth is set to ± 15 nulls limit.
Note that when RF filters are used, their respective bandwidths are used to determine the transmitter signal and receiver bandwidths. The Power Amp Bandwidth GUI value specified is retained for later use.
Use. To specify a filter model, select Use and browse to a filter model. For more information, see Filter Models.
Polarization
To specify a polarization model, select Use and select a polarization type. For descriptions of the polarization parameters, see Polarization.
Additional Gains and Losses
Post-Transmit Gains/Losses. To define a Gain or Loss, click Add. Enter a brief description of the Gain or Loss in the Identifier field and its value in the Gain field. Remember to make it negative if a Loss is being entered. Once the values are entered, you can click Remove to delete an entry from the table. To modify an existing entry, simply edit the fields in the grid. The value in the Post-Transmit field will reflect the net value of all gains and losses recorded in the table.
For more information on modeling gains and losses that affect performance but are not defined using built-in analytical models, see Post-Transmit and Pre-Demod Gains and Losses.