Open AccessSuperconducting spiral bandpass filter designed by a pseudo‐Fourier technique
Author(s) -
Huang Frederick,
Bolli Pietro,
Cresci Luca,
Mariotti Sergio,
Panella Dario,
LopezPerez Jose A.,
Garcia Pablo
Publication year - 2018
Publication title -
iet microwaves, antennas and propagation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.555
H-Index - 69
eISSN - 1751-8733
pISSN - 1751-8725
DOI - 10.1049/iet-map.2017.0940
Subject(s) - chebyshev filter , band pass filter , ripple , prototype filter , m derived filter , bandwidth (computing) , electronic engineering , filter (signal processing) , butterworth filter , passband , filter design , electronic filter topology , physics , low pass filter , mathematics , optics , topology (electrical circuits) , computer science , telecommunications , mathematical analysis , engineering , quantum mechanics , voltage , combinatorics , computer vision
An iterative technique to adjust ripple in a bandpass filter has been developed by curve‐fitting numerical data. It gives an approximate relation of ripple against filter coupling coefficients and resonator resonant frequencies instead of finding a Jacobian matrix for each individual filter, in exchange for making more iterations. Numerical examples show reasonable convergence for Chebyshev filters up to the 16th‐order, coupled quadruplets, coupled triplets and folded cross‐coupled filters. A bandpass filter for a radio telescope in Yebes, Spain is designed and measured, a tenth‐order superconducting spiral filter with 7% bandwidth, 2295 MHz centre frequency, <0.1 dB ripple and overall substrate size 30 mm × 8 mm. The 11 iterative simulations totalled 8.5 h of computer processing time.