Create biquad or double-biquad antenna


The biquad antenna is center fed and symmetric about its origin. The default length is chosen for an operating frequency of 2.8 GHz.

The width of the strip is related to the diameter an equivalent cylinder:


, where:

  • d is the diameter of equivalent cylindrical dipole.

  • r is the radius of equivalent cylindrical dipole.

For a given cylinder radius, use the cylinder2strip utility function to calculate the equivalent width. The default strip dipole is center-fed. The feed point coincides with the origin. The origin is located on the Y-Z plane.



bq = biquad creates a biquad antenna.


bq = biquad(Name,Value) creates a biquad antenna with additional properties specified by one or more name-value pair arguments. Name is the property name and Value is the corresponding value. You can specify several name-value pair arguments in any order as Name1, Value1, ..., NameN, ValueN. Properties not specified retain their default values.


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Number of loops for the biquad, specified as a scalar integer. Setting this property to 4 supports a double biquad antenna.

Example: 'NumLoops',4

Data Types: double

Length of two arms, specified as a scalar in meters. The default length is chosen for an operating frequency of 2.8 GHz.

Example: 'ArmLength',0.0206

Data Types: double

Biquad arm width, specified as a scalar in meters.

Example: 'Width',0.006

Data Types: double

Angle formed by biquad arms to the X-Y plane, specified a scalar in meters.

Example: 'ArmElevation', 50

Data Types: double

Lumped elements added to the antenna feed, specified a lumped element object handle. For more information, see lumpedElement.

Example: 'Load', lumpedelement. lumpedelement is the object handle for the load created using lumpedElement.

Example: bq.Load = lumpedElement('Impedance',75)

Tilt angle of the antenna, specified as a scalar or vector with each element unit in degrees. For more information, see Rotate Antennas and Arrays.

Example: 'Tilt',90

Example: 'Tilt',[90 90],'TiltAxis',[0 1 0;0 1 1] tilts the antenna at 90 degree about two axes, defined by vectors.

Data Types: double

Tilt axis of the antenna, specified as:

  • Three-element vectors of Cartesian coordinates in meters. In this case, each vector starts at the origin and lies along the specified points on the X-, Y-, and Z-axes.

  • Two points in space, each specified as three-element vectors of Cartesian coordinates. In this case, the antenna rotates around the line joining the two points in space.

  • A string input describing simple rotations around one of the principal axes, 'X', 'Y', or 'Z'.

For more information, see Rotate Antennas and Arrays.

Example: 'TiltAxis',[0 1 0]

Example: 'TiltAxis',[0 0 0;0 1 0]

Example: ant.TiltAxis = 'Z'

Object Functions

showDisplay antenna or array structure; Display shape as filled patch
infoDisplay information about antenna or array
axialRatioAxial ratio of antenna
beamwidthBeamwidth of antenna
chargeCharge distribution on metal or dielectric antenna or array surface
currentCurrent distribution on metal or dielectric antenna or array surface
designDesign prototype antenna or arrays for resonance at specified frequency
EHfieldsElectric and magnetic fields of antennas; Embedded electric and magnetic fields of antenna element in arrays
impedanceInput impedance of antenna; scan impedance of array
meshMesh properties of metal or dielectric antenna or array structure
meshconfigChange mesh mode of antenna structure
patternRadiation pattern and phase of antenna or array; Embedded pattern of antenna element in array
patternAzimuthAzimuth pattern of antenna or array
patternElevationElevation pattern of antenna or array
returnLossReturn loss of antenna; scan return loss of array
sparametersS-parameter object
vswrVoltage standing wave ratio of antenna


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Create a biquad antenna with arm angles at 50 degrees and view it.

bq = biquad('ArmElevation',50);

Calculate the impedance of a biquad antenna over a frequency span 2.5GHz-3GHz.

bq = biquad('ArmElevation',50);

Create and view a double biquad antenna using default property values.

ant = biquad('NumLoops',4)
ant = 
  biquad with properties:

        NumLoops: 4
       ArmLength: 0.0305
    ArmElevation: 45
           Width: 1.0000e-03
            Tilt: 0
        TiltAxis: [1 0 0]
            Load: [1x1 lumpedElement]


Introduced in R2015b