Development of highly selective compact high-temperature superconducting quad-band bandpass filter using interdigital feeding structure for radio astronomy. (1st February 2023)

• Record Type: Journal Article
• Authors: Rachi, Sota; Sakuma, Keita; Akahori, Takuya; Sekiya, Naoto
• Is Part Of: Superconductor science & technology. Volume 36:Number 2(2023)
• Publication Date: 2023-02-01
• Subjects: microwave filter -- quad-band bandpass filter -- stub-loaded resonator -- high-temperature superconductor; Superconductivity -- Periodicals; Superconductors -- Periodicals; 537.623
• DOI: 10.1088/1361-6668/acab38
• Languages: English
• ISSNs: 0953-2048

Abstract

Abstract: Astronomers at the Mizusawa Very Long Baseline Interferometry Observatory of the National Astronomical Observatory of Japan are promoting the development of broadband receivers in the ultra-high frequency (UHF) band. The presence of extensive radio frequency interferences (RFI) in the UHF band hinders continuous broadband radio observations in this band. A promising technical solution to this problem is to use a superconducting multi-band bandpass filter as it enables the bundling of several RFI-free bands. We have developed a high-temperature superconducting compact quad-band bandpass filter (QB-BPF) at 0.7, 1.4, 1.6, and 2.1 GHz with low loss and steep cutoff characteristics for broadband receivers. That consists of two six-pole dual-band bandpass filters. We have devised an interdigital feeding structure with a high degree of freedom that enables the external quality factor to be designed individually for each band. A compact QB-BPF was fabricated using double-sided YBa2 Cu3 Oy thin films on a 36.4 mm × 42.0 mm (0.22 λ g × 0.25 λ g ) Al2 O3 substrate. The measurement results agreed well with the simulated ones, indicating that the QB-BPF overcomes the problem of extensive RFI in the UHF band.