Analytical approach to the multiband filter synthesis and comparison to   other approaches
  A novel analytical approach to the synthesis of electrical (e.g. analogue, digital or microwave) filters is proposed. This approach allows to obtain lowest possible degree filters with given involved specification including e.g. many pass and stop bands, narrow transition bands, high attenuation at the stop bands and low magnitude oscillations at the pass bands. Comparison to other existing approaches is given. 
Andrei B. Bogatyrev, Sergei A. Goreinov, Sergei Yu. Lyamaev
cs.SY