beamwidth

Compute and display beamwidth of sensor element pattern

Since R2020b

Syntax

beamwidth(element,freq)

beamwidth(element,freq,Name,Value)

[bw,angles] = beamwidth(___)

Description

beamwidth(element,freq) plots the 2-D power pattern (in dB) of the element for all azimuth angles at an elevation angle of zero degrees. The plot displays the half-power beamwidth (in degrees) at the frequency specified in freq (in Hz) and the angles (in degrees) in azimuth at which the magnitude of the power pattern decreases by 3 dB from the peak of the main beam.

beamwidth(element,freq,Name,Value) plots the beamwidth with the specified parameter Name set to the specified Value. You can specify additional name-value pair arguments in any order as (Name1,Value1,...,NameN,ValueN).

Example: beamwidth(element,1e9,'Cut','Elevation)

[bw,angles] = beamwidth(___) returns the angular beamwidth bw (in degrees). The function also returns the corresponding angle values (in degrees) that mark the beamwidth.

Examples

Plot Beamwidth of Isotropic Antenna

Plot the beamwidth for an isotropic antenna at 1 GHz.

Create an isotropic antenna using a phased.IsotropicAntennaElement object.

antenna = phased.IsotropicAntennaElement('FrequencyRange',[800e6 1.2e9])

antenna = 
  phased.IsotropicAntennaElement with properties:

    FrequencyRange: [800000000 1.2000e+09]
       BackBaffled: false

Using the beamwidth function, plot the half-power (3 dB) beamwidth for the antenna. Use a frequency value of 1 GHz.

beamwidth(antenna, 1e9)

ans = 
360

Calculate Beamwidth and Angles of Cosine Antenna Element

Calculate the half-power beamwidth and angles of a cosine antenna element.

Create a phased.CosineAntennaElement object with the 'CosinePower' exponents set to 10.

myAnt = phased.CosineAntennaElement('CosinePower',[10 10])

myAnt = 
  phased.CosineAntennaElement with properties:

    FrequencyRange: [0 1.0000e+20]
       CosinePower: [10 10]

Compute the beamwidth and angles of the antenna element when it is operating at 1 GHz. Set 'dbDown' to 3 dB.

[BW,Ang] = beamwidth(myAnt,1e9,'dbDown',3)

BW = 
29.9600

Ang = 1×2

  -14.9800   14.9800

Input Arguments

element — Antenna or microphone element

Phased Array System Toolbox™ System object™

Antenna or microphone element, specified as a Phased Array System Toolbox System object.

freq — Frequency used to calculate beamwidth

scalar in Hz

Frequency used to calculate the beamwidth, specified as a scalar in Hz.

Example: 1e9

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: beamwidth(element,1e9,'Cut','Azimuth','CutAngle',45) plots the beamwidth of the antenna element that is operating at a frequency of 1 GHz, with the slice direction set to 'Azimuth', and the cut angle set to 45 degrees.

Cut — Slice direction in azimuth-elevation space

'Azimuth' (default) | 'Elevation'

The slice direction in azimuth-elevation space along which the beamwidth is computed, specified as the comma-separated pair consisting of 'Cut' and 'Azimuth' for the azimuth plane, and 'Cut' and 'Elevation' for the elevation plane.

CutAngle — Angle for plane to get required 2-D cut

0 (default) | scalar

Corresponding angle (in degrees) for the plane to get the required 2-D cut, specified as the comma-separated pair consisting of 'CutAngle' and a scalar. If 'Cut' is specified as 'Azimuth', then 'CutAngle' (Elevation) should lie between [−90, 90] degrees. If 'Cut' is specified as 'Elevation', then 'CutAngle' (Azimuth) should lie between [−180, 180] degrees.

Data Types: double

dBDown — Power value from peak of main lobe

3 (default) | Inf | positive scalar

Power value from the peak of the main lobe, specified as the comma-separated pair consisting of 'dBDown' and a positive scalar. The default value of 3 dB is equivalent to half-power beamwidth. To calculate the first-null beamwidth, specify the 'dBDown' value as Inf. Units are in dB.

Data Types: double

Output Arguments

bw — Angular beamwidth

scalar in degrees

Angular beamwidth of the sensor element, returned as a scalar in degrees.

Data Types: double

angles — Angle values of beamwidth

1-by-2 vector in degrees

Angle values of the beamwidth, returned as a 1-by-2 vector. The two elements in the vector [a_min, a_max] define the beamwidth bw as a_max−a_min.

Version History

Introduced in R2020b