3-D Printed Slotted Spherical Resonator Bandpass Filters With Spurious Suppression

In this paper, a third-order waveguide bandpass filter (BPF) based on slotted spherical resonators with a wide spurious-free stopband is presented. The resonator consists of a spherical cavity with slots opened at the top and bottom. Compared with a non-slotted spherical resonator, the slotted reson...

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Bibliographic Details
Published in:IEEE access 2019, Vol.7, p.128026-128034
Main Authors: Zhang, Fan, Gao, Sufang, Li, Jin, Yu, Yang, Guo, Cheng, Li, Sheng, Attallah, Moataz, Shang, Xiaobang, Wang, Yi, Lancaster, Michael J., Xu, Jun
Format: Article
Language:English
Subjects:
3-D printing
Band-pass filters
Bandpass filter
Bandpass filters
Cavity resonators
Couplings
Electromagnetic wave filters
Electroplating
Insertion loss
Laser beam melting
Lithography
Microwave filters
Q factors
Q-factor
Rapid prototyping
Resonant frequency
Resonator filters
selective laser melting
slotted spherical resonator
spurious suppression
stereolithography apparatus
Three dimensional printing
Waveguides
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Summary:In this paper, a third-order waveguide bandpass filter (BPF) based on slotted spherical resonators with a wide spurious-free stopband is presented. The resonator consists of a spherical cavity with slots opened at the top and bottom. Compared with a non-slotted spherical resonator, the slotted resonator suppresses the two spurious modes (TM 211 and TE 101 ) whilst maintaining the fundamental TM 101 mode. The unloaded quality factor of the TM 101 mode is not significantly degraded. This is achieved by interrupting surface current and radiating the unwanted spurious modes with the slots. The BPF is designed at a center frequency of 10 GHz with a fractional bandwidth of 1%. Two filter prototypes are fabricated, one using metal-based selective laser melting (SLM) and the other by polymer-based stereolithography apparatus (SLA) techniques. The slots also facilitate the copper electroplating process for the SLA-printed filter. The measured results show that the average passband insertion losses of the SLM- and SLA-printed filters are 0.33 and 0.2 dB, respectively. The corresponding passband return losses are better than 22 and 20 dB. The filters demonstrate excellent passband performance and wide spurious-free stopbands up to 16 GHz with stopband rejections of over 20 dB.
ISSN:2169-3536
2169-3536
DOI:10.1109/ACCESS.2019.2938972