Design and performance of a compact superconducting duplexer at VHF-band

A high-temperature superconductor (HTS) bandpass filter with special asymmetric cul-de-sac units (SACUs) is introduced and a compact low-radiating microstrip resonator is suggested for the filter realization. Such a filter is capable of providing better selectivity and higher out-of-band rejection and hence a decrease in adjacent-channel interference, which is of critical importance for mobile communication. This improvement of the filter characteristics results from an increase in the number of pairs of transmission zeros (TZs) on the imaginary axis on the complex plane when using the filter composed of the introduced SACUs, each providing a pair of TZs. An 11-pole filter consisting of two SACUs was fabricated using MgO substrate of 0.5 mm thickness with double-sided YBCO HTS film. Characterization of the filter at 77 K gave a central frequency of 2345 MHz, insertion loss 0.19 dB, an overall in-band return loss better than 15 dB, and an ultra-high band-edge steepness as a consequence of the two pairs of TZs. The measured characteristics are in good accord with those obtained by electromagnetic simulation.

Section: Introductionmentioning

confidence: 99%

Design of special asymmetric cul-de-sac unit configuration high temperature superconductor filter with multi-pair of transmission zeros

Zhou¹,

Long²,

Wu³

et al. 2020

“…The rapid development of wireless communications presents an urgent demand for high-performance radio frequency/ microwave bandpass filters. Filters with advantages such as low insertion loss, a high-quality factor and excellent out-ofband rejection are widely researched by scholars [1][2][3][4][5][6][7][8][9][10]. In order to obtain a better selectivity within a limited area of high-temperature superconducting (HTS) thin films, introducing cross coupling between non-adjacent resonators [11][12][13][14][15][16][17], adopting parallel topology [18][19][20] and extracted-pole technology [18][19][20][21][22][23][24] to realize the quasi-elliptic function [13][14][15][16][17][25][26][27][28][29][30][31][32][33][34][35][36][37] and generalized Chebyshev function [38]…”

Section: Introductionmentioning

confidence: 99%

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

Zhou¹,

Li²,

Long³

et al. 2018

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.

“…If each HTS filter is replaced by a superconducting multiplexer, the sizes and masses, as well as the insertion loss, can be further reduced for multiplexers having a certain quantity of channels [16]. Moreover, the T-junction branches make difficult optimization for multibranches more than two and difficult to implement high order bandpass filters with many pairs of transmission zeros (TZs) on a single piece of HTS wafer [17].…”

Section: Introductionmentioning

confidence: 99%

Miniaturized high-temperature superconducting multiplexer with cascaded quadruplet structure

Xu¹,

Liu²,

Su³

et al. 2015

In this paper, compact high temperature superconducting (HTS) multiplexers are presented for satellite communication applications. The first multiplexer consists of an input coupling node and three high-order bandpass filters, which is named triplexer. The node is realized by a loop microstrip line instead of conventional T-junction to eliminate the redundant susceptance due to combination of three filters. There are two eight-pole band-pass filters and one ten-pole band-pass filter with cascaded quadruplet structure for realizing high isolation. Moreover, the triplexer is extended to a multiplexer with six channels so as to verify the expansibility of the suggested approach. The triplexer is fabricated using double-sided YBa2Cu3O7 thin films on a 38 × 25 mm2 LaAlO3 substrate. The experimental results, when compared with those ones from the T-junction multiplexer, show that our multiplexer has lower insertion loss, smaller sizes and higher isolation between any two channels. Also, good agreement has been achieved between simulations and measurements, which illustrate the effectiveness of our methods for the design of high performance HTS multiplexers.