Source code for radarx.fundamentals.beam
"""
Beam Geometry and Resolution
============================
Functions related to radar beamwidth and spatial resolution.
.. autosummary::
:nosignatures:
:toctree: generated/
azimuthal_resolution
beamwidth_to_radians
compute_azimuth_resolution
compute_beamwidth
compute_volume_resolution
volume_resolution
References
----------
- Doviak, R. J., & Zrnić, D. S. (1993). Doppler Radar and Weather Observations. Academic Press.
"""
__all__ = [
"azimuthal_resolution",
"beamwidth_to_radians",
"compute_azimuth_resolution",
"compute_beamwidth",
"compute_volume_resolution",
"volume_resolution",
]
[docs]
def compute_beamwidth(wavelength, antenna_diameter):
"""
Compute the beamwidth of a radar.
Parameters
----------
wavelength : float
Radar wavelength [m].
antenna_diameter : float
Diameter of the radar antenna [m].
Returns
-------
float
Beamwidth in radians.
References
----------
- Doviak and Zrnić (1993), Eq. 3.5.2
"""
return 1.22 * wavelength / antenna_diameter
[docs]
def compute_azimuth_resolution(range_m, beamwidth_rad):
"""
Compute azimuthal resolution (cross-range resolution).
Parameters
----------
range_m : float
Radar range [m].
beamwidth_rad : float
Beamwidth [radians].
Returns
-------
float
Azimuthal resolution [m].
References
----------
- Doviak and Zrnić (1993), Section 3.5
"""
return range_m * beamwidth_rad
[docs]
def compute_volume_resolution(range_m, beamwidth_rad, pulse_length):
"""
Compute radar volume resolution.
Parameters
----------
range_m : float
Radar range [m].
beamwidth_rad : float
Beamwidth [radians].
pulse_length : float
Pulse length [m].
Returns
-------
float
Radar sampling volume [m^3].
References
----------
- Doviak and Zrnić (1993), Eq. 3.5.7
"""
az_res = compute_azimuth_resolution(range_m, beamwidth_rad)
return az_res * az_res * pulse_length
[docs]
def beamwidth_to_radians(beamwidth_deg):
"""
Convert beamwidth from degrees to radians.
Parameters
----------
beamwidth_deg : float
Beamwidth in degrees.
Returns
-------
float
Beamwidth in radians.
"""
import numpy as np
return np.deg2rad(beamwidth_deg)
[docs]
def azimuthal_resolution(range_m, beamwidth_deg):
"""
Compute azimuthal resolution given beamwidth in degrees.
Parameters
----------
range_m : float
Radar range [m].
beamwidth_deg : float
Beamwidth [degrees].
Returns
-------
float
Azimuthal resolution [m].
"""
bw_rad = beamwidth_to_radians(beamwidth_deg)
return compute_azimuth_resolution(range_m, bw_rad)
[docs]
def volume_resolution(range_m, bw_h_deg, bw_v_deg, pulse_length):
"""
Compute radar volume resolution using horizontal and vertical beamwidth in degrees.
Parameters
----------
range_m : float
Radar range [m].
bw_h_deg : float
Horizontal beamwidth [degrees].
bw_v_deg : float
Vertical beamwidth [degrees].
pulse_length : float
Pulse length [m].
Returns
-------
float
Radar sampling volume [m^3].
"""
import numpy as np
bw_h_rad = np.deg2rad(bw_h_deg)
bw_v_rad = np.deg2rad(bw_v_deg)
return range_m**2 * bw_h_rad * bw_v_rad * pulse_length / (4 * np.log(2))
