def METHOD_NAME(frequencies, filter_name):
    """
    Simple minicircuits filters.
    Check filter directory for available filters.
    """
    # parse input file and convert to default units
    directory = os.path.dirname(os.path.abspath(__file__))
    filename = os.path.join(directory, 'filter/{}_S2P'.format(filter_name), '{}_Minus40degC.S2P'.format(filter_name))
    if not os.path.exists(filename):
        filename = os.path.join(directory, 'filter/{}_S2P'.format(filter_name), '{}__UNIT_1.s2p'.format(filter_name))
        if not os.path.exists(filename):
            filename = glob.glob(os.path.join(directory, 'filter/{}_S2P'.format(filter_name), '{}*'.format(filter_name)))[0]
    data = np.loadtxt(filename, comments=['#', '!'])
    ff = data.T[0] * units.MHz
    S21 = 10**(data.T[3] / 20.) * np.exp(1j * data.T[4] * units.deg)
    get_S21 = intp.interp1d(ff, S21)
    response = np.zeros_like(frequencies, dtype=complex)
    mask = (frequencies > ff.min()) & (frequencies < ff.max())
    response[mask] = get_S21(frequencies[mask])
    return response