Unsolved theoretical problem in design of optimal low-pass filter for harmonic suppression in radio-transmitter output

The author offers to cooperate in development of an optimal harmonic-suppression output filter for power amplifiers. The commonly used elliptic-function filter is not optimal for this purpose: less attenuation is needed at higher frequencies in the stopband. An improved design should provide a value of
A_{\min}
that varies with frequency as the harmonic output of the amplifier varies with frequency.