The increasing demand on microwave spectrum for communication systems has been the driving force in the filter industry. There are increasing demands on high performance single- and multiple-band filters. In this work, different resonator structures have been investigated for narrow band filters. Using these structures, two single symmetric and asymmetric narrow passband HTS filters has been developed. A cost-function for an optimisation algorithm to achieve multiple passband filtering function has been discussed. Different HTS Filters have been designed and tested. A new analytical algorithm...