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resonantFrequency

Calculate and/or plot resonant frequency of antenna

Since R2024a

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    Syntax

    [fRES, zRES, Z, typRES] = resonantFrequency(object,frequency)
    [fRES, sRES, S] = resonantFrequency(object,frequency,Method="Sparameters")
    [fRES, ___] = resonantFrequency(___,Name=Value)
    resonantFrequency(___)

    Description

    example

    [fRES, zRES, Z, typRES] = resonantFrequency(object,frequency) calculates the resonant frequencies fRES and its corresponding impedances zRES and resonance type typRES (series or parallel) for the specified antenna object within a sweep of frequencies. fRES, zRES, and typRES are empty if no resonant frequency is detected within the frequency sweep, and fRES and zRES are vectors if there is more than one resonant frequency whereas typRES is a string array. Z is the vector of the entire impedance plot spanning across the sweep of frequencies.

    [fRES, sRES, S] = resonantFrequency(object,frequency,Method="Sparameters") calculates the resonant frequencies fRES and corresponding S11 value sRES for the specified antenna object. S is the vector of the entire S11 values spanning across the sweep of frequencies.

    [fRES, ___] = resonantFrequency(___,Name=Value) calculates the resonant frequency and other parameters using additional options specified by one or more Name-Value Arguments.

    resonantFrequency(___) plots the impedance for the specified frequency range and marks the resonant frequency on the plot.

    Examples

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    Open Live Script

    This example shows how to calculate and plot the resonant frequency of a dipole antenna using Impedance method and S-parameters method.

    Calculate and Plot Resonant Frequency using Impedance Method

    Create a dipole antenna operating at 75MHz. Calculate and plot the resonant frequency of a dipole over a frequency span of 50MHz - 100MHz.

    h = design(dipole,75e6);
resonantFrequency(h,50e6:1e6:100e6);

    Calculate and Plot Resonant Frequency using S-parameters Method

    Calculate and plot the resonant frequency of the same dipole, using S-parameters method, over the same frequency span.

    resonantFrequency(h,50e6:1e6:100e6,Method="Sparameters");

    Input Arguments

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    Antenna to calculate resonant frequency, specified as an antenna object.

    Example: dipole

    Frequency sweep in Hz to calculate the resonant frequency, specified as a positive vector.

    Example: [50e6:5e6:80e6]

    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.

    Example: Method="Sparameters"

    Flag to enable parallel pool, specified as a logical value. The default value is false. Set the flag to true or 1 to enable the parallel pool. Use parallel pool to speedup the resonant frequency calculations at multiple frequencies for computationally large antennas and arrays. To use this feature, you need a license to the Parallel Computing Toolbox™.

    Example: UseParallel=true

    Data Types: logical

    Method to use for resonant frequency calculation, specified as either "Impedance" or "Sparameters". The default method is "Impedance". When the method is specified as "Impedance", zero-crossings of the reactance are used to find the resonant frequency, and zRES and Z are the outputs. When the method is specified as "Sparameters", the negative peaks of S11 are used to find the resonant frequency. The output typRES (whether the impedance is series or parallel) is only supported when the method is "Impedance".

    Example: "Sparameters"

    Data Types: string

    Threshold value for impedance when the Method is "Impedance" or S11 when the Method is Sparameters, specified as a real scalar.

    Example: -12

    Data Types: double

    Reference impedance in ohms to calculate the S-parameters, specified as a positive real scalar. The default reference impedance is 50 ohms. Valid only when Method is Sparameters.

    Example: 75

    Data Types: double

    Logical flag to enable or disable data tips, specified as either true to enable or false to disable. By default, the data tips are enabled.

    Example: false

    Data Types: logical

    Output Arguments

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    Resonant frequency in Hz of the specified antenna, returned as either positive scalar value for a single resonance or a positive vector for multiple resonances within the specified frequency sweep.

    Example: 75.33e6

    Impedances in ohms corresponding to the resonant frequencies, returned as real or complex scalars or vectors. zRES is empty when no resonance is found within the specified frequency sweep. And zRES is a vector when multiple resonances are found within the specified frequency sweep.

    Example: 75

    Data Types: double
    Complex Number Support: Yes

    S11 values in dB corresponding to resonant frequencies, returned as a complex vector.

    Data Types: double
    Complex Number Support: Yes

    Impedance values in ohms over entire frequency span, returned as a complex vector.

    Data Types: double
    Complex Number Support: Yes

    S11 values in dB for the entire frequency sweep, returned as a complex vector.

    Data Types: double

    Resonance type, returned as either "Series", "Parallel" or "Unclear". When the reactance in the impedance plot touches zero but does not cross it, resonance type is returned as "Unclear".

    Example: "Parallel"

    Data Types: string

    Version History

    Introduced in R2024a

    See Also

    Functions