patternAzimuth
System object: phased.ReplicatedSubarray
Namespace: phased
Plot replicated subarray directivity or pattern versus azimuth
Syntax
patternAzimuth(sArray,FREQ)
patternAzimuth(sArray,FREQ,EL)
patternAzimuth(sArray,FREQ,EL,Name,Value)
PAT = patternAzimuth(___)
Description
patternAzimuth(
plots
the 2-D array directivity pattern versus azimuth (in dBi) for the
array sArray
,FREQ
)sArray
at zero degrees elevation angle.
The argument FREQ
specifies the operating frequency.
The integration used when computing array directivity has a minimum sampling grid of 0.1 degrees. If an array pattern has a beamwidth smaller than this, the directivity value will be inaccurate.
patternAzimuth(
,
in addition, plots the 2-D array directivity pattern versus azimuth (in dBi) for the array
sArray
,FREQ
,EL
)sArray
at the elevation angle specified by EL
.
When EL
is a vector, multiple overlaid plots are created.
patternAzimuth(
plots the array pattern with additional options specified by one or
more sArray
,FREQ
,EL
,Name,Value
)Name,Value
pair arguments.
returns
the array pattern. PAT
= patternAzimuth(___)PAT
is a matrix whose entries
represent the pattern at corresponding sampling points specified by
the 'Azimuth'
parameter and the EL
input
argument.
Input Arguments
sArray
— Replicated subarray
System object™
Replicated subarray, specified as a phased.ReplicatedSubarray
System object.
Example: sArray= phased.ReplicatedSubarray;
FREQ
— Frequency for computing directivity and pattern
positive scalar
Frequency for computing directivity and pattern, specified as a positive scalar. Frequency units are in hertz.
For an antenna or microphone element,
FREQ
must lie within the range of values specified by theFrequencyRange
or theFrequencyVector
property of the element. Otherwise, the element produces no response and the directivity is returned as–Inf
. Most elements use theFrequencyRange
property except forphased.CustomAntennaElement
andphased.CustomMicrophoneElement
, which use theFrequencyVector
property.For an array of elements,
FREQ
must lie within the frequency range of the elements that make up the array. Otherwise, the array produces no response and the directivity is returned as–Inf
.
Example: 1e8
Data Types: double
EL
— Elevation angles
1-by-N real-valued row vector
Elevation angles for computing sensor or array directivities and patterns, specified as a 1-by-N real-valued row vector. The quantity N is the number of requested elevation directions. Angle units are in degrees. The elevation angle must lie between –90° and 90°.
The elevation angle is the angle between the direction vector and the xy plane. When measured toward the z-axis, this angle is positive.
Example: [0,10,20]
Data Types: double
Name-Value Arguments
Specify optional pairs of arguments as
Name1=Value1,...,NameN=ValueN
, where Name
is
the argument name and Value
is the corresponding value.
Name-value arguments must appear after other arguments, but the order of the
pairs does not matter.
Before R2021a, use commas to separate each name and value, and enclose
Name
in quotes.
Type
— Displayed pattern type
'directivity'
(default) | 'efield'
| 'power'
| 'powerdb'
Displayed pattern type, specified as the comma-separated pair
consisting of 'Type'
and one of
'directivity'
— directivity pattern measured in dBi.'efield'
— field pattern of the sensor or array. For acoustic sensors, the displayed pattern is for the scalar sound field.'power'
— power pattern of the sensor or array defined as the square of the field pattern.'powerdb'
— power pattern converted to dB.
Example: 'powerdb'
Data Types: char
PropagationSpeed
— Signal propagation speed
speed of light (default) | positive scalar
Signal propagation speed, specified as the comma-separated pair
consisting of 'PropagationSpeed'
and a positive
scalar in meters per second.
Example: 'PropagationSpeed',physconst('LightSpeed')
Data Types: double
Weights
— Subarray weights
M-by-1 complex-valued column vector
Subarray weights, specified as the comma-separated pair consisting
of 'Weights'
and an M-by-1 complex-valued
column vector. Subarray weights are applied to the subarrays of the
array to produce array steering, tapering, or both. The dimension M is
the number of subarrays in the array.
Example: 'Weights',ones(10,1)
Data Types: double
Complex Number Support: Yes
SteerAngle
— Subarray steering angle
[0;0]
(default) | scalar | 2-element column vector
Subarray steering angle, specified as the comma-separated pair
consisting of 'SteerAngle'
and a scalar or a 2-by-1
column vector.
If 'SteerAngle'
is a 2-by-1 column vector,
it has the form [azimuth; elevation]
. The azimuth
angle must be between –180° and 180°, inclusive.
The elevation angle must be between –90° and 90°,
inclusive.
If 'SteerAngle'
is a scalar, it specifies
the azimuth angle only. In this case, the elevation angle is assumed
to be 0.
This option applies only when the 'SubarraySteering'
property
of the System object is set to 'Phase'
or 'Time'
.
Example: 'SteerAngle',[20;30]
Data Types: double
ElementWeights
— Weights applied to elements within subarray
1
(default) | complex-valued NSE-by-N
matrix
Subarray element weights, specified as complex-valued NSE-by-N matrix. Weights are applied to the individual elements within a subarray. All subarrays have the same dimensions and sizes. NSE is the number of elements in each subarray and N is the number of subarrays. Each column of the matrix specifies the weights for the corresponding subarray.
Dependencies
To enable this name-value pair, set the SubarraySteering
property of the array to 'Custom'
.
Data Types: double
Complex Number Support: Yes
Azimuth
— Azimuth angles
[-180:180]
(default) | 1-by-P real-valued row vector
Azimuth angles, specified as the comma-separated pair consisting
of 'Azimuth'
and a 1-by-P real-valued
row vector. Azimuth angles define where the array pattern is calculated.
Example: 'Azimuth',[-90:2:90]
Data Types: double
Parent
— Handle to axis
scalar
Handle to the axes along which the array geometry is displayed specified as a scalar.
Output Arguments
PAT
— Array directivity or pattern
L-by-N real-valued matrix
Array directivity or pattern, returned as an L-by-N
real-valued matrix. The dimension L is the number of azimuth values
determined by the 'Azimuth'
name-value pair argument. The dimension
N is the number of elevation angles, as determined by the
EL
input argument.
Examples
Azimuth Pattern of Array with Subarrays
Create a 2-element ULA of isotropic antenna elements, and arrange three copies to form a 6-element ULA. Plot the directivity azimuth pattern within a restricted range of azimuth angles from -30 to 30 degrees in 0.1 degree increments. Plot directivity for 0 degrees and 45 degrees elevation.
Create the array
fmin = 1e9; fmax = 6e9; c = physconst('LightSpeed'); lam = c/fmax; sIso = phased.IsotropicAntennaElement(... 'FrequencyRange',[fmin,fmax],... 'BackBaffled',false); sULA = phased.ULA('Element',sIso,... 'NumElements',2,'ElementSpacing',0.5); sRS = phased.ReplicatedSubarray('Subarray',sULA,... 'Layout','Rectangular','GridSize',[1 3],... 'GridSpacing','Auto');
Plot azimuth directivity pattern
fc = 1e9; wts = [0.862,1.23,0.862]'; patternAzimuth(sRS,fc,[0,45],'PropagationSpeed',physconst('LightSpeed'),... 'Azimuth',[-30:0.1:30],... 'Type','directivity',... 'Weights',wts);
More About
Directivity
Directivity describes the directionality of the radiation pattern of a sensor element or array of sensor elements.
Higher directivity is desired when you want to transmit more radiation in a specific direction. Directivity is the ratio of the transmitted radiant intensity in a specified direction to the radiant intensity transmitted by an isotropic radiator with the same total transmitted power
where Urad(θ,φ) is the radiant intensity of a transmitter in the direction (θ,φ) and Ptotal is the total power transmitted by an isotropic radiator. For a receiving element or array, directivity measures the sensitivity toward radiation arriving from a specific direction. The principle of reciprocity shows that the directivity of an element or array used for reception equals the directivity of the same element or array used for transmission. When converted to decibels, the directivity is denoted as dBi. For information on directivity, read the notes on Element Directivity and Array Directivity.
Version History
Introduced in R2015a
See Also
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