Miniaturization of high temperature superconductor filters with 2nd harmonic suppression by using quasi-fractal resonators

This paper presents two filters based on quasi-fractal resonators. The first one is composed with resonators changed from Hilbert fractal resonators, the results show that this filter is smaller than the Hilbert fractal filter at a lower frequency and even more powerful in suppressing the 2nd harmonic. The other one with a cascaded quadruplet(CQ) structure is an 8-pole band pass elliptic filter based on L-shaped quasi-fractal resonators. The final structure of the second filter is only in half size of the usual meandered line filter and the 2nd harmonic suppression is much better than the meandered line filter. Results show that the proposed two filters are both possess good quality in transmission response and capable of size reduction and 2nd harmonic suppression.