Cardioid antenna element
System object™ models an antenna with a Cardioid Response. Cardioid antennas are
often used in direction finding. The cardioid response can be implemented by placing two
isotropic radiators in an array, a quarter-wavelength apart and 90° out of phase. The default
rotation of the cardioid pattern has a null at 180° azimuth and 0° elevation. The 0° azimuth
and 0° elevation is considered to be the main response axis of the antenna. When placed in a
linear or a rectangular array, the main response axis is aligned with the array normal.
To compute the response of the antenna element for specified directions:
phased.CardioidAntennaElement object and set its properties.
Call the object with arguments, as if it were a function.
To learn more about how System objects work, see What Are System Objects?
creates a cardioid antenna System object,
antenna = phased.CardioidAntennaElement
antenna. This object models an antenna element whose
response is a cardioid with a null at 180° azimuth and 0° elevation.
creates a cardioid antenna object,
antenna = phased.CardioidAntennaElement(
antenna, with each specified
property set to the specified value. You can specify multiple name-value arguments in any
order. For example,
FrequencyRange=[1e6 1e9] specifies that the antenna
operates in a frequency range from 1 MHz to 1 GHz.
Unless otherwise indicated, properties are nontunable, which means you cannot change their
values after calling the object. Objects lock when you call them, and the
release function unlocks them.
If a property is tunable, you can change its value at any time.
For more information on changing property values, see System Design in MATLAB Using System Objects.
FrequencyRange— Operating frequency range
[0 1e20](default) | nonnegative, real-valued 1-by-2 row vector
Operating frequency range of the antenna, specified as a nonnegative, real-valued, 1-by-2 row
vector in the form
[LowerBound HigherBound]. The antenna
element has no response outside the specified frequency range. Units are in
NullAxisDirection— Null axis direction
Null axis direction, specified as one of these:
For more information, see Cardioid Response.
The object performs an initialization the first time the object is executed. This
initialization locks nontunable properties
and input specifications, such as dimensions, complexity, and data type of the input data.
If you change a nontunable property or an input specification, the System object issues an error. To change nontunable properties or inputs, you must first
release method to unlock the object.
FREQ— Operating frequency of antenna element
Operating frequency of the antenna element, specified as a nonnegative scalar or nonnegative, real-valued 1-by-L row vector. Frequency units are in Hz.
FREQ must lie within the range of values specified by the
FrequencyRange or the
property of the element. Otherwise, the element produces no response and the response is
–Inf. Element objects use the
FrequencyRange property, except for
phased.CustomAntennaElement, which uses the
RESP— Voltage response of antenna
Voltage response of the antenna element, returned as a matrix of size
M-by-L. In this matrix, M
represents the number of angles specified in
L represents the number of frequencies specified in
To use an object function, specify the
System object as the first input argument. For
example, to release system resources of a System object named
|Plot antenna or transducer element directivity and pattern versus elevation|
|Plot antenna or transducer element directivity and pattern versus azimuth|
|Plot antenna or transducer element directivity and patterns|
|Compute and display beamwidth of sensor element pattern|
|Directivity of antenna or transducer element|
|Antenna element polarization capability|
Create a cardioid antenna and plot its azimuth response. The antenna can work between 800 MHz and 1.2 GHz and has an operating frequency of 1 GHz.
element = phased.CardioidAntennaElement( ... FrequencyRange=[800e6 1.2e9]); fc = 1e9; pattern(element,fc,-180:180,0,CoordinateSystem="polar")
Find the response of the antenna at the boresight.
ang = [0 0]'; resp = element(fc,ang)
resp = 1
phased.CardioidAntennaElement object returns the field
response (also called field pattern) of the cardioid
If az is the azimuth angle in degrees and el is
the elevation angle in degrees, the field response has a different expression depending on
the value specified for
Usage notes and limitations:
patternElevation object functions are not supported.
See System Objects in MATLAB Code Generation (MATLAB Coder).