System object: phased.URA
Plot URA array directivity or pattern versus elevation
PAT = patternElevation(___)
the 2-D array directivity pattern versus elevation (in dBi) for the
sArray at zero degrees azimuth angle. When
a vector, multiple overlaid plots are created. The argument
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.
in addition, plots the 2-D element directivity pattern versus elevation
(in dBi) at the azimuth angle specified by
AZ is a vector, multiple overlaid plots
the array pattern.
PAT = patternElevation(___)
PAT is a matrix whose entries
represent the pattern at corresponding sampling points specified by
'Elevation' parameter and the
sArray— Uniform rectangular array
Uniform rectangular array, specified as a
phased.URA System object.
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
Parent— Handle to axis
Handle to the axes along which the array geometry is displayed specified as a scalar.
Create a 7x7-element URA of backbaffled omnidirectional transducer elements operating at 2 kHz. Assume the speed of sound in water is 1500 m/s. The elements are spaced less than one-half wavelength apart. Plot the array elevation directivity patterns for three different azimuth angles, -20, 0, and 15 degrees. The
patternElevation method always plots the array pattern in polar coordinates.
Create the array
element = phased.OmnidirectionalMicrophoneElement(... 'FrequencyRange',[20,3000],... 'BackBaffled',true); fc = 1000; c = 1500; lam = c/fc; array = phased.URA('Element',element,... 'Size',[7,7],... 'ElementSpacing',0.45*lam);
Display the pattern
Display the azimuth directivity pattern at 1 GHz in polar coordinates.
patternElevation(array,fc,[-20, 0, 15],... 'PropagationSpeed',c,... 'Type','directivity')
Display a subset of elevation angles
You can plot a smaller range of elevation angles by setting the
patternElevation(array,fc,[-20, 0, 15],... 'PropagationSpeed',c,... 'Type','directivity',... 'Elevation',[-45:45])
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.