Figure 1.
The structure of phased-array radar system simulator (PASIM).
Figure 1.
The structure of phased-array radar system simulator (PASIM).
Figure 2.
Operations of the key modules of PASIM: (a) time-domain system simulation; (b) weather radar data quality prediction.
Figure 2.
Operations of the key modules of PASIM: (a) time-domain system simulation; (b) weather radar data quality prediction.
Figure 3.
The antenna radiating element and array constructed in PASIM: (a) a simple patched element; (b) three-dimensional (3D) radiation pattern of the patch element; (c) an 8 × 8 planar subarray; (d) azimuth cut for the synthesized radiation pattern of an 80 × 80 planar array; (e) elevation cut for the synthesized radiation pattern of an 80 × 80 planar array.
Figure 3.
The antenna radiating element and array constructed in PASIM: (a) a simple patched element; (b) three-dimensional (3D) radiation pattern of the patch element; (c) an 8 × 8 planar subarray; (d) azimuth cut for the synthesized radiation pattern of an 80 × 80 planar array; (e) elevation cut for the synthesized radiation pattern of an 80 × 80 planar array.
Figure 4.
The impact of the Saleh nonlinearity model on an example of a 60-dB Taylor windowed linear frequency modulation (LFM) waveform and autocorrelation function (ACF): (a) distortion of the waveform envelope; (b) ACF of the waveform before and after nonlinear distortion.
Figure 4.
The impact of the Saleh nonlinearity model on an example of a 60-dB Taylor windowed linear frequency modulation (LFM) waveform and autocorrelation function (ACF): (a) distortion of the waveform envelope; (b) ACF of the waveform before and after nonlinear distortion.
Figure 5.
Typical array radiation patterns in PASIM by incorporating the impact of channel-to-channel (C2C) instability: (a) impacts of the random channel amplitude and phase errors; (b) impacts of phase shifter quantization error based on 5-bit phase shifters.
Figure 5.
Typical array radiation patterns in PASIM by incorporating the impact of channel-to-channel (C2C) instability: (a) impacts of the random channel amplitude and phase errors; (b) impacts of phase shifter quantization error based on 5-bit phase shifters.
Figure 6.
Examples of PASIM scan outputs, when the specific waveforms of an LFM, a Taylor-windowed LFM, and an example nonlinear frequency modulation (NLFM) waveform are used to estimate reflectivity (ZH) of a sector scan for a tornado case: (a) matched filter output for LFM; (b) simulated ZH for LFM; (c) ZH scatter plot for LFM; (d) matched filter output for windowed LFM; (e) simulated ZH for windowed LFM; (f) ZH scatter plot for windowed LFM; (g) matched filter output for NLFM; (h) simulated ZH for NLFM; (i) ZH scatter plot for NLFM.
Figure 6.
Examples of PASIM scan outputs, when the specific waveforms of an LFM, a Taylor-windowed LFM, and an example nonlinear frequency modulation (NLFM) waveform are used to estimate reflectivity (ZH) of a sector scan for a tornado case: (a) matched filter output for LFM; (b) simulated ZH for LFM; (c) ZH scatter plot for LFM; (d) matched filter output for windowed LFM; (e) simulated ZH for windowed LFM; (f) ZH scatter plot for windowed LFM; (g) matched filter output for NLFM; (h) simulated ZH for NLFM; (i) ZH scatter plot for NLFM.
Figure 7.
Simulated weather radar moments from the generic radar example, and comparison with the Nest-Generation radar (NEXRAD) “truth” fields for Case 1: (a) reflectivity, (b) differential reflectivity, (c) correlation coefficient, (d) differential phase.
Figure 7.
Simulated weather radar moments from the generic radar example, and comparison with the Nest-Generation radar (NEXRAD) “truth” fields for Case 1: (a) reflectivity, (b) differential reflectivity, (c) correlation coefficient, (d) differential phase.
Figure 8.
Simulated weather radar moments from the generic radar example, and comparison with the NEXRAD “truth” fields for Case 2: (a) reflectivity, (b) differential reflectivity, (c) correlation coefficient, (d) differential phase.
Figure 8.
Simulated weather radar moments from the generic radar example, and comparison with the NEXRAD “truth” fields for Case 2: (a) reflectivity, (b) differential reflectivity, (c) correlation coefficient, (d) differential phase.
Figure 9.
Simulated polarimetric radar moments generated from the advanced technology demonstrator (ATD) model of PASIM, and comparison with the “truth” weather fields for Case 2: (a) reflectivity, (b) differential reflectivity, (c) correlation coefficient, (d) differential phase, (e) averaged differential reflectivity bias along azimuth from −45° to 45°.
Figure 9.
Simulated polarimetric radar moments generated from the advanced technology demonstrator (ATD) model of PASIM, and comparison with the “truth” weather fields for Case 2: (a) reflectivity, (b) differential reflectivity, (c) correlation coefficient, (d) differential phase, (e) averaged differential reflectivity bias along azimuth from −45° to 45°.
Figure 10.
Simulated polarimetric radar moments generated from the 2-m-diameter cylindrical polarimetric phased-array radar (CPPAR) model of PASIM, and comparison with the “truth” weather fields for Case 2: (a) reflectivity, (b) differential reflectivity, (c) correlation coefficient, (d) differential phase, (e) averaged differential reflectivity bias along azimuth from −45° to 45°.
Figure 10.
Simulated polarimetric radar moments generated from the 2-m-diameter cylindrical polarimetric phased-array radar (CPPAR) model of PASIM, and comparison with the “truth” weather fields for Case 2: (a) reflectivity, (b) differential reflectivity, (c) correlation coefficient, (d) differential phase, (e) averaged differential reflectivity bias along azimuth from −45° to 45°.
Figure 11.
Simulated polarimetric radar moments generated from the 10-m-diameter CPPAR model of PASIM, and comparison with the “truth” weather fields for Case 2: (a) reflectivity, (b) differential reflectivity, (c) correlation coefficient, (d) differential phase, (e) averaged differential reflectivity bias along azimuth from −45° to 45°.
Figure 11.
Simulated polarimetric radar moments generated from the 10-m-diameter CPPAR model of PASIM, and comparison with the “truth” weather fields for Case 2: (a) reflectivity, (b) differential reflectivity, (c) correlation coefficient, (d) differential phase, (e) averaged differential reflectivity bias along azimuth from −45° to 45°.
Table 1.
The basic parameters of the antenna element and array.
Table 1.
The basic parameters of the antenna element and array.
Parameter | Value |
---|
Type | Patch |
Size | 5.24 × 5.24 cm |
Polarization | Dual linear polarized |
Transmit | Yes |
Receive | Yes |
Number of elements in azimuth | 80 |
Number of elements in elevation | 80 |
Table 2.
Summary of the main radar components, parameters, and models used in the simulations. HPA—high-power amplifier.
Table 2.
Summary of the main radar components, parameters, and models used in the simulations. HPA—high-power amplifier.
Radar Component/Parameter/Model | Value |
---|
Antenna element | Dual-polarized patch |
HPA nonlinearity | Saleh model |
Digital phase shifter | 5-bit |
Waveform | Rectangular pulse |
Weather target model | Covariance matrix |
Table 3.
Next-Generation Radar (NEXRAD) requirements of data quality for basic weather radar moments.
Table 3.
Next-Generation Radar (NEXRAD) requirements of data quality for basic weather radar moments.
Radar Variable | Bias | Standard Deviation |
---|
Reflectivity | 1 dB | 1 dB |
Radial velocity | 1 m/s | 1 m/s |
Spectrum width | 1 m/s | 1 m/s |
Differential reflectivity | 0.1 dB | 0.2 dB |
Correlation coefficient | 0.005 | 0.01 |
Differential phase | 1° | 2° |
Table 4.
System specifications of a generic radar.
Table 4.
System specifications of a generic radar.
Radar Parameters | Values |
---|
Frequency | 2800 MHz |
Antenna Gain | 45.5 dB |
Beamwidth | 1.0° |
First sidelobe | −32 dB |
Waveform | Rectangular pulse |
Pulse width | 1.6 μs |
Pulse repetition frequency | 300 Hz |
Range resolution | 250 m |
Peak power | 700 kW |
Noise figure | 2.7 dB |
Table 5.
System parameters of the simulated advanced technology demonstrator (ATD).
Table 5.
System parameters of the simulated advanced technology demonstrator (ATD).
Radar Parameters | Values |
---|
Frequency | 2800 MHz |
Array size | 4 × 4 m |
Number of subarrays | 100 |
Beamwidth | Azimuth 1.8° |
First sidelobe | −30.3 dB |
Waveform | Rectangular pulse |
Pulse width | 1.6 μs |
Pulse repetition frequency | 300 Hz |
Range resolution | 250 m |
Peak power | 768 W per subarray |
Noise figure | 2.7 dB |
Table 6.
System parameters of the simulated cylindrical polarimetric phased-array radar (CPPAR).
Table 6.
System parameters of the simulated cylindrical polarimetric phased-array radar (CPPAR).
Radar Parameters | Values for 2-m CPPAR | Values for 10-m CPPAR |
---|
Frequency | 2800 MHz | 2800 MHz |
Array size | 2 m diameter | 10 m diameter |
Number of excited columns | 24 | 156 |
Beamwidth | Azimuth 5.2° | Azimuth 1.1° |
First sidelobe | −30.1 dB | −30.5 dB |
Waveform | Rectangular pulse | Rectangular pulse |
Pulse width | 1.6 μs | 1.6 μs |
Pulse repetition frequency | 300 Hz | 300 Hz |
Range resolution | 250 m | 250 m |
Peak power | 80 W per column | 80 W per column |
Noise figure | 2.7 dB | 2.7 dB |
Table 7.
Summary of error statistics for the tornado scenario (Case 1).
Table 7.
Summary of error statistics for the tornado scenario (Case 1).
Radar Variable | Generic Radar | ATD | 2-m-diameter CPPAR | 10-m-diameter CPPAR |
---|
| 0.81 dB | 1.66 dB | 3.79 dB | 0.82 dB |
| 0.18 dB | 0.39 dB | 0.98 dB | 0.21 dB |
| 0.008 | 0.01 | 0.016 | 0.008 |
| 1.19° | 2.65° | 5.66° | 1.35° |
Table 8.
Summary of error statistics for the convective precipitation scenario (Case 2).
Table 8.
Summary of error statistics for the convective precipitation scenario (Case 2).
Radar Variable | Generic Radar | ATD | 2-m-diameter CPPAR | 10-m-diameter CPPAR |
---|
| 0.78 dB | 1.42 dB | 2.84 dB | 0.79 dB |
| 0.17 dB | 0.36 dB | 0.87 dB | 0.19 dB |
| 0.006 | 0.007 | 0.014 | 0.006 |
| 1.12° | 2.41° | 4.58° | 1.22° |