blakechart
Description
blakechart(
creates a range-angle-height plot (also called a Blake chart) for a narrowband radar
antenna. This chart shows the maximum radar range as a function of target elevation. In
addition, the Blake chart displays lines of constant range and lines of constant height.
The input consists of the vertical coverage pattern vcp
,vcpangles
)vcp
and vertical
coverage pattern angles vcpangles
, both produced by radarvcd
.
The range in the range-height-angle chart is the propagated range and the height is relative to the origin of the ray. It is assumed that the antenna height is less than 1000 ft (about 305 meters) above ground level. Normal atmospheric refraction is taken into account using the CRPL Exponential Reference Atmosphere Model. Scattering and ducting are assumed to be negligible.
blakechart(___,
allows you to
specify additional input parameters using name-value arguments. You can specify multiple
name-value arguments in any order with any of the previous syntaxes.Name,Value
)
Examples
Display Vertical Coverage Diagram
Display the vertical coverage diagram of an antenna transmitting at 100 MHz and placed 20 meters above the ground. Set the free-space range to 100 km. Use default plotting parameters.
freq = 100e6; ant_height = 20; rng_fs = 100; [vcp, vcpangles] = radarvcd(freq,rng_fs,ant_height); blakechart(vcp, vcpangles);
Display Vertical Coverage Diagram Specifying Maximum Range and Height
Display the vertical coverage diagram of an antenna transmitting at 100 MHz and placed 20 meters above the ground. Set the free-space range to 100 km. Set the maximum plotting range to 300 km and the maximum plotting height to 250 km.
freq = 100e6; ant_height = 20; rng_fs = 100; [vcp, vcpangles] = radarvcd(freq,rng_fs,ant_height); rmax = 300; hmax = 250; blakechart(vcp,vcpangles,rmax,hmax)
Display Vertical Coverage Diagram of Sinc Pattern Antenna
Plot the range-height-angle curve of a radar having a sinc-function antenna pattern.
Specify antenna pattern
Specify the antenna pattern as a sinc function.
pat_angles = linspace(-90,90,361)'; pat_u = 1.39157/sind(90/2)*sind(pat_angles); pat = sinc(pat_u/pi);
Specify radar and environment parameters
Set the transmitting frequency to 100 MHz, the free-space range to 100 km, the antenna tilt angle to , and place the antenna 20 meters above the ground. Assume a surface roughness of one meter.
freq = 100e6; ant_height = 10; rng_fs = 100; tilt_ang = 0; surf_roughness = 1;
Create radar range-height-angle data
Obtain the vertical coverage pattern values and angles for the radar antenna.
[vcp, vcpangles] = radarvcd(freq,rng_fs,ant_height,... 'RangeUnit','km','HeightUnit','m',... 'AntennaPattern',pat,... 'PatternAngles',pat_angles,'TiltAngle',tilt_ang,... 'SurfaceHeightStandardDeviation',surf_roughness/(2*sqrt(2)));
Plot radar range-height-angle data
Set the maximum plotting range to 300 km and the maximum plotting height to 250,000 m. Choose the range units as kilometers, 'km'
, and the height units as meters, 'm'
. Set the range and height axes scale powers to 1/2.
rmax = 300; hmax = 250e3; blakechart(vcp, vcpangles, rmax, hmax, 'RangeUnit','km',... 'ScalePower',1/2,'HeightUnit','m');
Input Arguments
vcp
— Vertical coverage pattern
real-valued column vector | real-valued matrix
Vertical coverage pattern, specified as a real-valued column vector or matrix. The vertical
coverage pattern is the actual maximum range of the radar. Each column of
vcp
corresponds to an individual vertical coverage pattern. Each
row of vcp
corresponds to one of the angles specified in
vcpangles
. Values are expressed in kilometers unless you change
the unit of measure using the RangeUnit
name-value argument.
Example: [282.3831; 291.0502; 299.4252]
Data Types: double
vcpangles
— Vertical coverage pattern angles
real-valued column vector
Vertical coverage pattern angles, specified as a real-valued column vector. Each element of
vcpangles
specifies the elevation angle in degrees at which a
vertical coverage pattern is measured. The set of angles ranges from –90° to
90°.
Example: [2.1480; 2.2340; 2.3199]
Data Types: double
rmax
— Maximum range of plot
real-valued scalar
Maximum range of plot, specified as a real-valued scalar. Range units are specified by the
'RangeUnit'
name-value argument.
Example: 200
Data Types: double
hmax
— Maximum height of plot
real-valued scalar
Maximum height of plot, specified as a real-valued scalar. Height units are specified by the
'HeightUnit'
name-value argument.
Example: 100000
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.
Example: 'RangeUnit','m'
RangeUnit
— Radar range units
'km'
(default) | 'nmi'
| 'mi'
| 'ft'
| 'm'
| 'kft'
HeightUnit
— Height units
'km'
(default) | 'nmi'
| 'mi'
| 'ft'
| 'm'
| 'kft'
Height units, specified as one of 'nmi'
, 'mi'
,
'km'
, 'ft'
, 'm'
, or
'kft'
denoting nautical miles, miles, kilometers, feet, meters,
or kilofeet, respectively. This name-value argument specifies the units for the
maximum height hmax
.
Example: 'm'
Data Types: char
ScalePower
— Scale power
0.25
(default) | real-valued scalar
Scale power, specified as a scalar in the range [0, 1]. This argument specifies the range and height axis scale power.
Example: 0.5
Data Types: double
SurfaceRefractivity
— Surface refractivity
313
(default) | real-valued scalar
Surface refractivity in N-units, specified as a nonnegative real-valued scalar. The surface
refractivity is a parameter of the CRPL Exponential Reference Atmosphere Model used by
blakechart
.
Data Types: double
RefractionExponent
— Refraction exponent
0.143859
(default) | real-valued scalar
Refraction exponent, specified as a nonnegative real-valued scalar. The refraction exponent is
a parameter of the CRPL Exponential Reference Atmosphere Model used by
blakechart
.
Data Types: double
AntennaHeight
— Antenna height
0
(default) | real-valued scalar
Antenna height, specified as a real-valued scalar. When you provide the antenna
height, the height in the Blake chart is the height above ground level. Otherwise, the
height in the Blake chart is relative to the origin of the ray, and the function
assumes that the antenna is less than 1000 ft (about 305 m) above ground level. Use
the HeightUnit
argument to specify the units of
AntennaHeight
.
Data Types: double
FaceColor
— Face color of vertical coverage pattern patch
color name | short name | hexadecimal color code | RGB triplet | 'none'
Face color of vertical coverage pattern patch, specified as a color name, a short
name, a hexadecimal color code, an RGB triplet, or 'none'
. If you
specify more than one color, the number of colors must match the number of columns of
vcp
.
For a custom color, specify an RGB triplet or a hexadecimal color code.
An RGB triplet is a three-element row vector whose elements specify the intensities of the red, green, and blue components of the color. The intensities must be in the range
[0,1]
, for example,[0.4 0.6 0.7]
.A hexadecimal color code is a string scalar or character vector that starts with a hash symbol (
#
) followed by three or six hexadecimal digits, which can range from0
toF
. The values are not case sensitive. Therefore, the color codes"#FF8800"
,"#ff8800"
,"#F80"
, and"#f80"
are equivalent.
Alternatively, you can specify some common colors by name. This table lists the named color options, the equivalent RGB triplets, and hexadecimal color codes.
Color Name | Short Name | RGB Triplet | Hexadecimal Color Code | Appearance |
---|---|---|---|---|
"red" | "r" | [1 0 0] | "#FF0000" | |
"green" | "g" | [0 1 0] | "#00FF00" | |
"blue" | "b" | [0 0 1] | "#0000FF" | |
"cyan"
| "c" | [0 1 1] | "#00FFFF" | |
"magenta" | "m" | [1 0 1] | "#FF00FF" | |
"yellow" | "y" | [1 1 0] | "#FFFF00" | |
"black" | "k" | [0 0 0] | "#000000" | |
"white" | "w" | [1 1 1] | "#FFFFFF" | |
"none" | Not applicable | Not applicable | Not applicable | No color |
Here are the RGB triplets and hexadecimal color codes for the default colors MATLAB® uses in many types of plots.
RGB Triplet | Hexadecimal Color Code | Appearance |
---|---|---|
[0 0.4470 0.7410] | "#0072BD" | |
[0.8500 0.3250 0.0980] | "#D95319" | |
[0.9290 0.6940 0.1250] | "#EDB120" | |
[0.4940 0.1840 0.5560] | "#7E2F8E" | |
[0.4660 0.6740 0.1880] | "#77AC30" | |
[0.3010 0.7450 0.9330] | "#4DBEEE" | |
[0.6350 0.0780 0.1840] | "#A2142F" |
Example: 'black'
Example: 'k'
Example: [0.850 0.325 0.098]
Example: '#D95319'
Data Types: double
| char
| string
EdgeColor
— Edge color of vertical coverage pattern patch
color name | short name | hexadecimal color code | RGB triplet | 'none'
Edge color of vertical coverage pattern patch, specified as a color name, a short
name, a hexadecimal color code, an RGB triplet, or 'none'
. If you
specify more than one color, the number of colors must match the number of columns of
vcp
.
For a custom color, specify an RGB triplet or a hexadecimal color code.
An RGB triplet is a three-element row vector whose elements specify the intensities of the red, green, and blue components of the color. The intensities must be in the range
[0,1]
, for example,[0.4 0.6 0.7]
.A hexadecimal color code is a string scalar or character vector that starts with a hash symbol (
#
) followed by three or six hexadecimal digits, which can range from0
toF
. The values are not case sensitive. Therefore, the color codes"#FF8800"
,"#ff8800"
,"#F80"
, and"#f80"
are equivalent.
Alternatively, you can specify some common colors by name. This table lists the named color options, the equivalent RGB triplets, and hexadecimal color codes.
Color Name | Short Name | RGB Triplet | Hexadecimal Color Code | Appearance |
---|---|---|---|---|
"red" | "r" | [1 0 0] | "#FF0000" | |
"green" | "g" | [0 1 0] | "#00FF00" | |
"blue" | "b" | [0 0 1] | "#0000FF" | |
"cyan"
| "c" | [0 1 1] | "#00FFFF" | |
"magenta" | "m" | [1 0 1] | "#FF00FF" | |
"yellow" | "y" | [1 1 0] | "#FFFF00" | |
"black" | "k" | [0 0 0] | "#000000" | |
"white" | "w" | [1 1 1] | "#FFFFFF" | |
"none" | Not applicable | Not applicable | Not applicable | No color |
Here are the RGB triplets and hexadecimal color codes for the default colors MATLAB uses in many types of plots.
RGB Triplet | Hexadecimal Color Code | Appearance |
---|---|---|
[0 0.4470 0.7410] | "#0072BD" | |
[0.8500 0.3250 0.0980] | "#D95319" | |
[0.9290 0.6940 0.1250] | "#EDB120" | |
[0.4940 0.1840 0.5560] | "#7E2F8E" | |
[0.4660 0.6740 0.1880] | "#77AC30" | |
[0.3010 0.7450 0.9330] | "#4DBEEE" | |
[0.6350 0.0780 0.1840] | "#A2142F" |
Example: 'black'
Example: 'k'
Example: [0.850 0.325 0.098]
Example: '#D95319'
Data Types: double
| char
| string
Parent
— Plot axes
current axes (default) | Axes
object
Plot axes, specified as an Axes
object. If you do not specify the
axes, then the blakechart
function creates a range-angle-height
plot in the current axes.
More About
CRPL Exponential Reference Atmosphere Model
Atmospheric refraction evidences itself as a deviation in an electromagnetic ray from a straight line due to variation in air density as a function of height. The Central Radio Propagation Laboratory (CRPL) exponential reference atmosphere model treats refraction effects by assuming that the index of refraction n(h) and the refractivity N decay exponentially with height. The model defines
where Ns is the atmospheric refractivity value (in units of 10–6) at the surface of the earth, Rexp is the decay constant, and h is the height above the surface in kilometers. Thus
The default value of Ns is 313
N-units and can be modified using the SurfaceRefractivity
name-value
argument in functions that accept it. The default value of
Rexp is 0.143859 km–1 and can be modified using the RefractionExponent
name-value argument in functions that accept it.
References
[1] Blake, Lamont V. Machine Plotting of Radar Vertical-Plane Coverage Diagrams. Naval Research Laboratory Report 7098, 1970.
[2] Bean, B.R., and G.D. Thayer. "Central Radio Propagation Laboratory Exponential Reference Atmosphere." Journal of Research of the National Bureau of Standards, Section D: Radio Propagation 63D, no. 3 (November 1959): 315. https://doi.org/10.6028/jres.063D.031.
Extended Capabilities
C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.
Version History
Introduced in R2021a
See Also
Apps
Functions
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