def get_return_losses(excitation_names, excitation_name_prefix=''):
    """Get the list of all the Returnloss from a list of exctitations. If no excitation is provided it will provide a full list of return Losses
    Example: excitation_names ["1","2"] is_touchstone_expression=False output ["S(1,1)",, S(2,2)]
    Example: excitation_names ["S(1,1)","S(1,2)", S(2,2)] is_touchstone_expression=True output ["S(1,1)",, S(2,2)]

    Parameters
    ----------
    excitation_names :
        list of excitation to include
    excitation_name_prefix :
         (Default value = '')

    Returns
    -------
    type
        list of string representing Return Losses of excitations

    """
    spar = []
    if excitation_name_prefix:
        excitation_names = [i for i in excitation_names if excitation_name_prefix.lower() in i.lower()]
    for i in excitation_names:
        spar.append("S({},{})".format(i, i))
    return spar