Compute and display beamwidth of an array
plots the 2-D power pattern (in dB) of the
array for all azimuth angles
at a fixed elevation angle of zero degrees. The plot displays the half-power beamwidth (in
degrees) at the frequency specified in
freq (in Hz) and the angles (in
degrees) in azimuth at which the magnitude of the power pattern decreases by 3 dB from the
peak of the main beam.
Plot the beamwidth of a sonar array operating at a frequency of 2 kHz when the propagation speed of sound in water is 1500 m/s.
The sonar array consists of a 20-element uniform linear array (ULA). Consider the element of the ULA to be a backbaffled
phased.IsotropicProjector with a
VoltageResponse of 100 Volts and with a
FrequencyRange from 10 Hz to 300 kHz. Create a
phased.ULA object to model the uniform linear array.
projector = phased.IsotropicProjector('BackBaffled',true,... 'VoltageResponse',100,'FrequencyRange',[10 300000])
projector = phased.IsotropicProjector with properties: VoltageResponse: 100 FrequencyRange: [10 300000] BackBaffled: true
myArray = phased.ULA('Element',projector,'NumElements',20,... 'ElementSpacing',1500/200e3/2)
myArray = phased.ULA with properties: Element: [1x1 phased.IsotropicProjector] NumElements: 20 ElementSpacing: 0.0037 ArrayAxis: 'y' Taper: 1
beamwidth function, calculate and plot the 6 dB beamwidth of the sonar array.
ans = 6.9200
Calculate the half-power beamwidth and angles of a 20-element uniform linear array (ULA) of cosine antenna elements.
phased.CosineAntennaElement object with the
'CosinePower' exponents set to 1.5.
myAnt = phased.CosineAntennaElement
myAnt = phased.CosineAntennaElement with properties: FrequencyRange: [0 1.0000e+20] CosinePower: [1.5000 1.5000]
phased.ULA object to model a 20-element ULA of cosine antenna elements. These elements are spaced at 0.5 meters on the azimuth plane.
array = phased.ULA('Element',myAnt,'NumElements',20)
array = phased.ULA with properties: Element: [1x1 phased.CosineAntennaElement] NumElements: 20 ElementSpacing: 0.5000 ArrayAxis: 'y' Taper: 1
Compute the beamwidth and angles of the array when it is operating at 3e8 Hz. Specify the beamwidth to be computed along the elevation plane.
[BW,Ang] = beamwidth(array,3e8,'Cut','Elevation')
BW = 74.8200
Ang = 1×2 -37.4100 37.4100
freq— Frequency used to calculate beamwidth
Frequency used to calculate the beamwidth, specified as a scalar in Hz.
comma-separated pairs of
the argument name and
Value is the corresponding value.
Name must appear inside quotes. You can specify several name and value
pair arguments in any order as
beamwidth(array,3e8,'Cut','Azimuth','CutAngle',45)plots the beamwidth of the array that is operating at a frequency of 0.3 GHz, with the slice direction set to
'Azimuth', and the cut angle set to 45 degrees.
Cut— Slice direction in azimuth-elevation space
The slice direction in azimuth-elevation space along which the beamwidth is
computed, specified as the comma-separated pair consisting of
'Azimuth' for the azimuth plane,
'Elevation' for the elevation
CutAngle— Angle for plane to get required 2-D cut
0(default) | scalar
Corresponding angle (in degrees) for the plane to get the required 2-D cut,
specified as the comma-separated pair consisting of
and a scalar. If
'Cut' is specified as
should lie between [−90, 90] degrees. If
'Cut' is specified as
should lie between [−180, 180] degrees.
dBDown— Power value from peak of main lobe
3(default) | positive scalar
Power value (in dB) from the peak of the main lobe, specified as the
comma-separated pair consisting of
'dBDown' and a positive
scalar. The default value is 3 dB, which translates to half-power beamwidth. To
calculate first-null beamwidth, specify the
'dBDown' value as
PropagationSpeed— Propagation speed
3×10^8m/s (speed of light) (default) | positive scalar
Propagation speed, specified as the comma-separated pair consisting of
'PropagationSpeed' and a positive scalar (in m/s).
Weights— Weights applied to array
Weights applied to the array of sensor elements, specified as the comma-separated
pair consisting of
'Weights' and a length-N
column vector, where N is the number of elements in the
bw— Angular beamwidth
Angular beamwidth of the array of sensor elements, returned as a scalar in degrees.
angles— Angle values of beamwidth
Angle values of the beamwidth, returned as a 1-by-2 vector. The two elements in the
amax] define the beamwidth