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rcscylinder

Radar cross section of cylinder

Since R2021a

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Syntax

rcspat = rcscylinder(r1,r2,height,c,fc)
rcspat = rcscylinder(r1,r2,height,c,fc,az,el)
rcspat = rcscylinder(___,model=Model)
[rcspat,azout,elout] = rcscylinder(___)

Description

rcspat = rcscylinder(r1,r2,height,c,fc) returns the radar cross section pattern of an elliptical cylinder having a semi-major axis, r1, a semi-minor axis, r2, and a height, height. The radar cross section is a function of signal frequency, fc, and signal propagation speed, c. The bottom of the cylinder lies on the xy-plane. The height of the cylinder points along the positive z-axis.

example

rcspat = rcscylinder(r1,r2,height,c,fc,az,el) also specifies the azimuth angles, az, and elevation angles, el, at which to compute the radar cross section.

example

rcspat = rcscylinder(___,model=Model) returns the radar cross section pattern calculated for the specified model, Model. (since R2024b)

example

[rcspat,azout,elout] = rcscylinder(___) also returns the azimuth angles, azout, and elevation angles, elout, at which the radar cross section patterns are computed. You can use these output arguments with any of the previous syntaxes.

example

Examples

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Open Live Script

Display the radar cross section (RCS) pattern as a function of azimuth and elevation for an elliptical cylinder whose semi-major axis is 12.5 cm and whose semi-minor axis is 9 cm. The cylinder height is 1 m. The operating frequency is 4.5 GHz.

Specify the cylinder geometry and signal parameters. 

c = physconst('Lightspeed');
fc = 4.5e9;
rada = 0.125;
radb = 0.090;
hgt = 1;

Compute the RCS for all directions using the default direction values.

[rcspat,azresp,elresp] = rcscylinder(rada,radb,hgt,c,fc);
imagesc(azresp,elresp,pow2db(rcspat))
colorbar
xlabel('Azimuth Angle (deg)')
ylabel('Elevation Angle (deg)')
title('Elliptic Cylinder RCS (dBsm)')

Figure contains an axes object. The axes object with title Elliptic Cylinder RCS (dBsm), xlabel Azimuth Angle (deg), ylabel Elevation Angle (deg) contains an object of type image.

Open Live Script

Plot the radar cross section (RCS) pattern of an elliptical cylinder as a function of elevation at a constant azimuth angle of 5∘. The cylinder has a semi-major axis of 12.5 cm and a semi-minor axis of 9 cm. The cylinder height is 1 m. The operating frequency is 4.5 GHz.

Specify the cylinder geometry and signal parameters. 

c = physconst('Lightspeed');
fc = 4.5e9;
rada = 0.125;
radb = 0.090;
hgt = 1;

Compute the RCS for all elevation angles at a fixed azimuth angle of 5∘.

el = -90:90;
az = 5;
[rcspat,azresp,elresp] = rcscylinder(rada,radb,hgt,c,fc,az,el);
plot(elresp,pow2db(rcspat))
xlabel('Elevation Angle (deg)')
ylabel('RCS (dBsm)')
title('Elliptic Cylinder RCS as Function of Elevation')
grid on

Figure contains an axes object. The axes object with title Elliptic Cylinder RCS as Function of Elevation, xlabel Elevation Angle (deg), ylabel RCS (dBsm) contains an object of type line.

Open Live Script

Plot the radar cross section (RCS) of an elliptical cylinder as a function of frequency for a fixed direction. The cylinder has as semi-major axis of 12.5 cm and a semi-minor axis of 9 cm. The cylinder height is 1 m.

Specify the cylinder geometry and signal parameters. 

c = physconst('Lightspeed');
rada = 0.125;
radb = 0.090;
hgt = 1;

Compute radar cross sections as a function of frequency for a fixed azimuth and elevation.

az = 5.0;
el = 20.0;
fc = (100:100:4000)*1e6;
[rcspat,azpat,elpat] = rcscylinder(rada,radb,hgt,c,fc,az,el);
disp([azpat,elpat])
     5    20

plot(fc/1e6,pow2db(squeeze(rcspat)))
xlabel('Frequency (MHz)')
ylabel('RCS (dBsm)')
title('Cylinder RCS as Function of Frequency')
grid on

Figure contains an axes object. The axes object with title Cylinder RCS as Function of Frequency, xlabel Frequency (MHz), ylabel RCS (dBsm) contains an object of type line.

Since R2024b

Open Live Script

Plot the radar cross section (RCS) pattern of an circular cylinder as a function of elevation. The cylinder has radius of 12.5 cm and the cylinder height is 1 m. The operating frequency is 3.5 GHz.

Specify the cylinder geometry and signal parameters. 

c = physconst('Lightspeed');
fc = 3.5e9;
r = 0.125;
hgt = 1;

Compute the RCS for all elevation angles at a fixed azimuth angle of 0∘.

el = -90:0.5:90;
rcspat = rcscylinder(r,r,hgt,c,fc,0,el);
plot(el,pow2db(rcspat))
ylim([-50 10])
xlabel('Elevation Angle (deg)')
ylabel('RCS (dBsm)')
title('Circular Cylinder RCS (Default Model)')
grid on

Figure contains an axes object. The axes object with title Circular Cylinder RCS (Default Model), xlabel Elevation Angle (deg), ylabel RCS (dBsm) contains an object of type line.

Since R2024b

Open Live Script

Plot the radar cross section (RCS) pattern of an circular cylinder as a function of elevation using the Knott model. The cylinder has radius of 12.5 cm and the cylinder height is 1 m. The operating frequency is 3.5 GHz.

Specify the cylinder geometry and signal parameters. 

c = physconst('Lightspeed');
fc = 3.5e9;
r = 0.125;
hgt = 1;

Compute the RCS for all elevation angles at a fixed azimuth angle of 0∘.

el = -90:90;
rcspat = rcscylinder(r,r,hgt,c,fc,0,el,model="Knott");
plot(el,pow2db(rcspat))
ylim([-50 10])
xlabel('Elevation Angle (deg)')
ylabel('RCS (dBsm)')
title('Circular Cylinder RCS (Knott Model)')
grid on

Figure contains an axes object. The axes object with title Circular Cylinder RCS (Knott Model), xlabel Elevation Angle (deg), ylabel RCS (dBsm) contains an object of type line.

Input Arguments

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Length of semi-major axis of cylinder, specified as a positive scalar. Units are in meters.

Example: 5.5

Data Types: double

Length of semi-minor axis of cylinder, specified as a positive scalar. Units are in meters.

Example: 3.0

Data Types: double

Height of cylinder, specified as a positive scalar. Units are in meters.

Example: 3.0

Data Types: double

Signal propagation speed, specified as a positive scalar. Units are in meters per second. For the SI value of the speed of light, use physconst('LightSpeed').

Example: 3e8

Data Types: double

Frequency for computing radar cross section, specified as a positive scalar or positive, real-valued, 1-by-L row vector. Frequency units are in Hz.

Example: [100e6 200e6]

Data Types: double

Azimuth angles for computing directivity and pattern, specified as a real-valued 1-by-M row vector where M is the number of azimuth angles. Angle units are in degrees. Azimuth angles must lie between –180° and 180°, inclusive.

The azimuth angle is the angle between the x-axis and the projection of a direction vector onto the xy-plane. The azimuth angle is positive when measured from the x-axis toward the y-axis.

Example: -45:2:45

Data Types: double

Elevation angles for computing directivity and pattern, specified as a real-valued, 1-by-N row vector where N is the number of desired elevation directions. Angle units are in degrees. Elevation angles must lie between –90° and 90°, inclusive.

The elevation angle is the angle between a direction vector and xy-plane. The elevation angle is positive when measured towards the z-axis.

Example: -75:1:70

Data Types: double

Tip

To construct a circular cylinder, set r2 equal to r1.

Since R2024b

Radar cross section (RCS) model, specified as one of "Small Wavelength" or "Knott". The "Small Wavelength" model is applicable when the wavelength (freq2wavelen(fc)) is small in comparison to both the length and the radius of the cylinder. The "Knott" model is applicable for circular cylinders (r2 equals r1) and includes contributions from the cylinder ends. There is no azimuthal dependency for the "Knott" model. The default model is "Small Wavelength".

Data Types: string | char

Output Arguments

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Radar cross section pattern, returned as a real-valued N-by-M-by-L array. N is the length of the vector returned in the elout argument. M is the length of the vector returned in the azout argument. L is the length of the fc vector. Units are in meters-squared.

Data Types: double

Azimuth angles for computing directivity and pattern, returned as a real-valued 1-by-M row vector where M is the number of azimuth angles specified by the az input argument. Angle units are in degrees.

The azimuth angle is the angle between the x-axis and the projection of the direction vector onto the xy-plane. The azimuth angle is positive when measured from the x-axis toward the y-axis.

Data Types: double

Elevation angles for computing directivity and pattern, returned as a real-valued 1-by-N row vector where N is the number of elevation angles specified in el output argument. Angle units are in degrees.

The elevation angle is the angle between the direction vector and xy-plane. The elevation angle is positive when measured towards the z-axis.

Data Types: double

More About

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Azimuth and Elevation

This section describes the convention used to define azimuth and elevation angles.

The azimuth angle of a vector is the angle between the x-axis and its orthogonal projection onto the xy-plane. The angle is positive when going from the x-axis toward the y-axis. Azimuth angles lie between –180° and 180° degrees, inclusive. The elevation angle is the angle between the vector and its orthogonal projection onto the xy-plane. The angle is positive when going toward the positive z-axis from the xy-plane. Elevation angles lie between –90° and 90° degrees, inclusive.

References

[1] Crispin, J. W. and A. L. Maffett. Radar Cross-Section Estimation for Simple Shapes. Proceedings of the IEEE 53, no. 8 (August 1965): 833–48.

[2] Knott, Eugene F., John F. Shaffer, and Micahel T. Tuley. Radar Cross Section, 2nd Ed. Raleigh, NC: Scitech Publishing, Inc., 2004.

[3] Mahafza, Bassem. Radar Systems Analysis and Design Using MATLAB, 3rd Ed. Boca Raton, FL: Chapman & Hall/CRC, 2013.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

Version History

Introduced in R2021a

See Also

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