TY - JOUR
T1 - Theory and Design of Tunable Full-Mode and Half-Mode Ferrite Waveguide Isolators
AU - Ghaffar, Farhan A.
AU - Bray, Joey R.
AU - Vaseem, Mohammed
AU - Roy, Langis
AU - Shamim, Atif
N1 - KAUST Repository Item: Exported on 2020-10-01
Acknowledgements: This work was supported by the King Abdullah University of Science and Technology, Royal Military College (RMC) of Canada and OntarioTech University (UOIT).
PY - 2019/4/25
Y1 - 2019/4/25
N2 - Ferrite isolators are attractive due to their excellent isolation, low loss, good linearity, and high-power performance. However, these devices usually operate over a single-frequency band. Multiband applications are possible if the isolation bandwidth of an isolator can be tuned. This paper presents a tunable waveguide-based full-mode ferrite isolator as well as a more compact half-mode tunable isolator, both fabricated on yttrium-iron-garnet substrates. For the first time, theory and design guidelines for the center frequency, bandwidth, and tuning of the ferrite isolators' unidirectional magnetostatic surface wave (MSW) mode are presented. The proposed theoretical model reveals that the isolation bandwidth can exceed 100% if the magnetization-to-bias field ratio is higher than 8. Although the full-mode design is fabricated using a conventional subtractive technique, the half-mode design is implemented using inkjet printing technology. The full-mode isolator provides a maximum bandwidth of 45% and a peak isolator figure of merit (IFM) of over 65 dB at 7 GHz, whereas the half-mode design has a maximum bandwidth of 59% and a peak IFM of 76.7 dB at 7.5 GHz. The tuning of the center frequency is from 7 to 10.7 GHz for the full-mode and from 4.4 to 9.9 GHz for the half-mode design using magnetic field strengths up to 2500 and 2400 Oe, respectively. This paper demonstrates the versatility of ferrite isolators as tunable microwave devices for reconfigurable RF applications.
AB - Ferrite isolators are attractive due to their excellent isolation, low loss, good linearity, and high-power performance. However, these devices usually operate over a single-frequency band. Multiband applications are possible if the isolation bandwidth of an isolator can be tuned. This paper presents a tunable waveguide-based full-mode ferrite isolator as well as a more compact half-mode tunable isolator, both fabricated on yttrium-iron-garnet substrates. For the first time, theory and design guidelines for the center frequency, bandwidth, and tuning of the ferrite isolators' unidirectional magnetostatic surface wave (MSW) mode are presented. The proposed theoretical model reveals that the isolation bandwidth can exceed 100% if the magnetization-to-bias field ratio is higher than 8. Although the full-mode design is fabricated using a conventional subtractive technique, the half-mode design is implemented using inkjet printing technology. The full-mode isolator provides a maximum bandwidth of 45% and a peak isolator figure of merit (IFM) of over 65 dB at 7 GHz, whereas the half-mode design has a maximum bandwidth of 59% and a peak IFM of 76.7 dB at 7.5 GHz. The tuning of the center frequency is from 7 to 10.7 GHz for the full-mode and from 4.4 to 9.9 GHz for the half-mode design using magnetic field strengths up to 2500 and 2400 Oe, respectively. This paper demonstrates the versatility of ferrite isolators as tunable microwave devices for reconfigurable RF applications.
UR - http://hdl.handle.net/10754/652871
UR - https://ieeexplore.ieee.org/document/8699110
UR - http://www.scopus.com/inward/record.url?scp=85069755843&partnerID=8YFLogxK
U2 - 10.1109/tmag.2019.2910028
DO - 10.1109/tmag.2019.2910028
M3 - Article
SN - 0018-9464
VL - 55
SP - 1
EP - 8
JO - IEEE Transactions on Magnetics
JF - IEEE Transactions on Magnetics
IS - 8
ER -