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beamwidth2ap

Computes aperture length of unweighted antenna from beamwidth

    Description

    example

    d = beamwidth2ap(hpbw,lambda) computes the aperture length d of an unweighted antenna from its half-power one-way beamwidth hpbw. lambda specifies the radar wavelength.

    example

    d = beamwidth2ap(hpbw,lambda,azb) also specifies the azimuth impulse broadening factor azb.

    Examples

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    Compute the aperture length of a radar from its half-power beamwidth. The radar is designed to operate at a wavelength of 2 centimeters. The radar has a half-power beamwidth of one degree. Use the default azimuth broadening factor.

    lambda = 2e-2;
    bw = 1;
    aplen = beamwidth2ap(bw,lambda)
    aplen = 1.1459
    

    Estimate the aperture lengths of two side-looking airborne radars operating at wavelengths of 1, 2, and 3 centimeters. The radars have beamwidths of 2 and 3 degrees in the azimuth dimension.

    lambda = [1,2,3]*1e-2;
    bw = [2,3];
    aplen = beamwidth2ap(bw,lambda)
    aplen = 2×3
    
        0.2865    0.5730    0.8594
        0.1910    0.3820    0.5730
    
    

    Compute the aperture length of a radar operating at a wavelength of 2 centimeters. The radar has a beamwidth of 2 deg in the azimuth direction. Use an azimuth broadening factor of 1.5.

    lambda = 2e-2;
    bw = 2;
    azbf = 1.5;
    ap = beamwidth2ap(bw,lambda,azbf)
    ap = 0.8594
    

    Estimate the aperture length of each side of a rectangular aperture antenna. The antenna operates at a wavelength of 10 cm. In this case, the input beamwidth array bw describes the two beamwidths of the same antenna. The radar has a half-power beamwidth of 1 degree along one dimension and a half-power beamwidth of 2 degrees along the other.

    bw = [1,2];
    lambda = 0.01;
    ap = beamwidth2ap(bw,lambda)
    ap = 2×1
    
        0.5730
        0.2865
    
    

    Input Arguments

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    Half-power one-way beamwidth, specified as a positive scalar or as a J-by-K real-valued vector of positive values. Matrix rows correspond to the length of d and columns correspond to the length of lambda. Units are in degrees.

    Radar wavelength, specified as a positive real scalar or a length-K vector of real values.

    Example: 1.5

    Data Types: double

    Azimuth impulse broadening factor, specified as a positive real scalar due to data weighting or windowing for side lobe control. The quantity is the actual –3 dB main lobe width with respect to the nominal width. Typical window functions such as hamming or hann exhibit azimuth impulse broadening factors in the range of 1 to 1.5.

    Example: 1.2

    Data Types: double

    Output Arguments

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    Length of unweighted antenna, returned as a positive scalar or length-J vector of positive values. Units are in meters.

    Example: [3.5,4.2]

    Data Types: double

    Algorithms

    The half-power beamwidth (in degrees) for a rectangular aperture is 180λ/πd where λ is the radar wavelength and d is the aperture length. The azimuth broadening factor b multiplies the beamwidth to produce a half-power beamwidth of 180bλ/πd.

    Extended Capabilities

    C/C++ Code Generation
    Generate C and C++ code using MATLAB® Coder™.

    See Also

    Introduced in R2021b