A Compact HTS Duplexer for Communication Application

Abstract

A compact L-band high temperature superconducting (HTS) microstrip input duplexer for satellite communication application has been developed. The duplexer has two output channels with center frequencies at 1200 and 1250 MHz, respectively. It was fabricated on a single piece of 2-in double-sided YBCO thin film on LaAlO 3 substrate with a dimension of 26 × 42 mm. The duplexer consists of a T-junction and two bandpass filters, i.e., a ten-pole filter and an eight-pole filter for the two transmission channels, respectively. Both of the two HTS bandpass filters were specially designed to suppress the second-harmonic spurious passband. Moreover, an HTS bandstop filter is added to the duplexer to improve the out-of-band rejection at a special frequency band. As a result of the preceding special designs, in addition to a very low insertion loss (0.2 dB), considerably sharp band edge (21 dB/MHz), and good voltage standing wave ratio (better than 1.4:1), much deeper out-of-band rejection (more than 75 dB) can be realized in a much wider frequency range, i.e., up to 3 GHz, which is almost three times above the center frequency of the passbands. Although all the elements of the duplexer are integrated within a single-piece YBCO film and the layout is compact, excellent isolation (higher than 80 dB) between the two channels has still been achieved.Index Terms-Bandpass filter, bandstop filter, high temperature superconducting (HTS) duplexer. His current research interests are HTS microwave devices and microwave tunable filters.

An L-band HTS duplexer with improved performance

“…A quasi-lumped resonator constructed by a meandered inductive line in parallel with an interdigital capacitor was first developed by Zhou et al [21] and then successfully used in designing a compact L-band microstrip HTS manifold-coupled input duplexer [19]. With this resonator structure, the cross couplings with opposite changes can be realized in the way shown in Figure 3, where all the computer simulations were carried out using full-wave electromagnetic simulation software Sonnet [22].…”

“…However, few of them have high performance in all of their operating parameters, including the insertion loss (<0.2 dB), return loss (<-14 dB), out-of-band rejection (>70 dB) and channel isolation (>80 dB). In particular, none were designed with consideration of the group delay, which is as important as high selectivity since high capacity digital signals are transmitted on many communication systems.In a recent work, we reported on a compact L-band microstrip HTS manifold-coupled input duplexer with high *Corresponding author (email: yshe@aphy.iphy.ac.cn) selectivity performance for satellite communication application [19]. In this paper, we present an improved HTS duplexer that not only has high selectivity but also takes group delay flatness into consideration.…”

“…In a recent work, we reported on a compact L-band microstrip HTS manifold-coupled input duplexer with high *Corresponding author (email: yshe@aphy.iphy.ac.cn) selectivity performance for satellite communication application [19]. In this paper, we present an improved HTS duplexer that not only has high selectivity but also takes group delay flatness into consideration.…”

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

“…High temperature superconducting (HTS) filters have many advantages such as extremely low insertion loss, steep band-edges, and high out-of-band rejection compared with conventional filters [1][2][3]. Duplexers and multiplexers comprising compact microstrip HTS filters are attractive for mobile and satellite communications systems [4][5][6][7][8].…”

“…To achieve this result both channels in the duplexer must be properly matched. Generally, there are two design approaches to realize HTS duplexers: the hybrid-coupled approach and the manifold-coupled approach [6][7][8]. Duplexers employing hybrid-coupled approach have the advantage of low return loss at the input port.…”