with a better impedance match to the connecting waveguides compared to the Chebyshev filter or image-parameter filters. Waveguide filters will usually require stepped impedance matching at their input and output. This is especially true of corrugated waveguide designs such as the waffle-iron filter which have a high input impedance compared to the waveguide to which it is connected. A better match results in fewer impedance steps being required and a significant reduction in bulk and weight. Waveguide designs are very bulky compared to other technologies but are preferred for microwave high-power applications and where low loss is needed. In applications such as airborne radar, weight and bulk are important considerations. There is a further advantage of the Achieser–Zolotarev filter over the Chebyshev in distributed-element filter designs. The dimensions of the elements of the Achieser–Zolotarev tend to be more convenient to manufacture. Internal gaps tend to be larger and the impedance changes tend to be smaller (making for a smaller change in mechanical dimensions). These same features increase the power-handling capability of the assembly. An adaptation of the Achieser–Zolotarev filter has applications for enhancement and restoration of images and video. In this role 2-D FIR filters are required of the bandstop filter form with extremely narrow stopbands. Such filters can be adapted from a 1-D Achieser–Zolotarev filter. See also Elliptic filter (Cauer filter), occasionally called a Zolotarev filter. References Bibliography Bowen, E.G. (ed), CSIRO Radiophysics Laboratory staff, A Textbook of Radar, Cambridge University Press, 1954 . Cameron, Richard J.; Kudsia, Chandra M.; Mansour, Raafat R., Microwave Filters for Communication Systems, John Wiley & Sons, 2018 . Grebennikov, Andre, RF and Microwave Transmitter Design, John Wiley & Sons, 2011 . Hansen, Robert C., Phased Array Antennas, Wiley, 2009 . Levy, Ralph "Tapered corrugated waveguide low-pass filters", IEEE Transactions on Microwave Theory and Techniques, vol. 21, iss. 8, pp. 526–532, August 1973. Morgan, Matthew A., Reflectionless Filters, Artech House, 2017 . Newman, D.J., Reddy, A.R., "Rational approximations to II", Canadian Journal of Mathematics, vol. 32, no. 2, pp. 310–316, April 1980. Nwajana, Augustine Onyenwe; Yeo, Kenneth Siok Kiam, Practical Approach to Substrate Integrated Waveguide (SIW) Diplexer, IGI Global, 2020 . Pinkus, Allan, "Zolotarev polynomials", in, Hazewinkel, Michiel (ed), Encyclopaedia of Mathematics, Supplement III, Springer Science & Business Media, 2001 . Zahradnik, Pavel; Vlček, Miroslav, "Analytical design of 2-D narrow bandstop FIR filters", pp. 56–63 in, Computational Science — ICCS 2004: Proceedings of the