Novel configuration of a HTS filter with adjustable transmission zeros based on a modified cascaded quartet structure

Abstract

A novel configuration for adjusting the relative position of transmission zeros (TZs) based on the cascaded quartet (CQ) structure filter is proposed. By simply introducing joint cross coupling (JCC) between two adjacent CQ units of the filter and changing its coupling strength, the relative position of TZs produced by the conventional CQ units can be altered easily so as to achieve better selectivity and out-of-band rejection. The filter with the proposed configuration is named a quasi-CQ (QCQ) configuration filter in this paper. The symmetrical QCQ configuration filter can obtain the frequency response of the asymmetrical filter, so the design difficulty of filters with multiple pairs of separated TZs is greatly reduced. A series of prototypes of QCQ configuration filters is given and analyzed to provide design guidance for designers in the future. Finally, the correctness and feasibility of the proposed approach are verified by fabricating and measuring a symmetrical high-temperature superconducting QCQ configuration filter, and the test results accord well with the simulated ones.

Design of High-Order Resonator HTS Diplexer with Very Different FBW

“…According to the theory presented in [15], the coupling coefficient is determined by the interaction of electrical and magnetic coupling, as shown in Equation (10). Therefore, when electric field coupling and magnetic field coupling offset each other, the resonator can achieve weak coupling, which is conducive to the design of the narrowband or ultranarrowband filters, for example, the paper [16]. On the contrary, if the electric and magnetic field coupling are separated, the resonator can achieve strong coupling from the electric or magnetic field.…”

“…Based on the two resonators in Figures 4 and 6, the external coupling structure of direct tap feeding in Figure 8 can be constructed. The external quality factor (Q e1 /Q e2 ) in Equation ( 12) [16] can be calculated by simulating and adjusting the position of the Tjunction connected to the resonator with IE3D. The relationship curve between the external quality factor of the type I resonator and h 1 can be obtained, and the relationship curve between the external quality factor of the type II resonator and h 2 can be obtained, as shown in Figure 9, wherein h 1 is the distance from the tapping position to the upper edge of the type I resonator, and h 2 is the distance from the tapping position to the symmetrical line (A − A') of the type II resonator.…”