Tunable Filters Using Defected Ground Structures at Millimeter-Wave Frequencies
This paper explores the potential of phase change materials (PCM) for dynamically tuning the frequency response of a dumbbell u-slot defected ground structure (DGS)-based band stop filter. The DGSs are designed using co-planar waveguide (CPW) line structure on top of a barium strontium titanate (Ba&...
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MDPI AG
2024-12-01
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| author | Kaushik Annam Birhanu Alemayehu Eunsung Shin Guru Subramanyam |
| author_facet | Kaushik Annam Birhanu Alemayehu Eunsung Shin Guru Subramanyam |
| author_sort | Kaushik Annam |
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| description | This paper explores the potential of phase change materials (PCM) for dynamically tuning the frequency response of a dumbbell u-slot defected ground structure (DGS)-based band stop filter. The DGSs are designed using co-planar waveguide (CPW) line structure on top of a barium strontium titanate (Ba<sub>0.6</sub>Sr<sub>0.4</sub>TiO<sub>3</sub>) (BST) thin film. BST film is used as the high-dielectric material for the planar DGS. Lower insertion loss of less than −2 dB below the lower cutoff frequency, and enhanced band-rejection with notch depth of −39.64 dB at 27.75 GHz is achieved by cascading two-unit cells, compared to −12.26 dB rejection with a single-unit cell using BST thin film only. Further tunability is achieved by using a germanium telluride (GeTe) PCM layer. The electrical properties of PCM can be reversibly altered by transitioning between amorphous and crystalline phases. We demonstrate that incorporating a PCM layer into a DGS device allows for significant tuning of the resonance frequency: a shift in resonance frequency from 30.75 GHz to 33 GHz with a frequency shift of 2.25 GHz is achieved, i.e., 7.32% tuning is shown with a single DGS cell. Furthermore, by cascading two DGS cells with PCM, an even wider tuning range is achievable: a shift in resonance frequency from 27 GHz to 30.25 GHz with a frequency shift of 3.25 GHz is achieved, i.e., 12.04% tuning is shown by cascading two DGS cells. The results are validated through simulations and measurements, showcasing excellent agreement. |
| format | Article |
| id | doaj-art-49ce3838d2fa491083e4d369efff9ef4 |
| institution | Kabale University |
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| language | English |
| publishDate | 2024-12-01 |
| publisher | MDPI AG |
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| series | Micromachines |
| spelling | doaj-art-49ce3838d2fa491083e4d369efff9ef42025-01-24T13:41:59ZengMDPI AGMicromachines2072-666X2024-12-011616010.3390/mi16010060Tunable Filters Using Defected Ground Structures at Millimeter-Wave FrequenciesKaushik Annam0Birhanu Alemayehu1Eunsung Shin2Guru Subramanyam3Center of Excellence for Thin-Film Research and Surface Engineering (CETRASE), Department of Electrical and Computer Engineering, University of Dayton, Dayton, OH 45469, USACenter of Excellence for Thin-Film Research and Surface Engineering (CETRASE), Department of Electrical and Computer Engineering, University of Dayton, Dayton, OH 45469, USACenter of Excellence for Thin-Film Research and Surface Engineering (CETRASE), Department of Electrical and Computer Engineering, University of Dayton, Dayton, OH 45469, USACenter of Excellence for Thin-Film Research and Surface Engineering (CETRASE), Department of Electrical and Computer Engineering, University of Dayton, Dayton, OH 45469, USAThis paper explores the potential of phase change materials (PCM) for dynamically tuning the frequency response of a dumbbell u-slot defected ground structure (DGS)-based band stop filter. The DGSs are designed using co-planar waveguide (CPW) line structure on top of a barium strontium titanate (Ba<sub>0.6</sub>Sr<sub>0.4</sub>TiO<sub>3</sub>) (BST) thin film. BST film is used as the high-dielectric material for the planar DGS. Lower insertion loss of less than −2 dB below the lower cutoff frequency, and enhanced band-rejection with notch depth of −39.64 dB at 27.75 GHz is achieved by cascading two-unit cells, compared to −12.26 dB rejection with a single-unit cell using BST thin film only. Further tunability is achieved by using a germanium telluride (GeTe) PCM layer. The electrical properties of PCM can be reversibly altered by transitioning between amorphous and crystalline phases. We demonstrate that incorporating a PCM layer into a DGS device allows for significant tuning of the resonance frequency: a shift in resonance frequency from 30.75 GHz to 33 GHz with a frequency shift of 2.25 GHz is achieved, i.e., 7.32% tuning is shown with a single DGS cell. Furthermore, by cascading two DGS cells with PCM, an even wider tuning range is achievable: a shift in resonance frequency from 27 GHz to 30.25 GHz with a frequency shift of 3.25 GHz is achieved, i.e., 12.04% tuning is shown by cascading two DGS cells. The results are validated through simulations and measurements, showcasing excellent agreement.https://www.mdpi.com/2072-666X/16/1/60defected ground structure (DGS)phase change material (PCM)frequency tuningdumbbell u-slotreconfigurable devicestunable filters |
| spellingShingle | Kaushik Annam Birhanu Alemayehu Eunsung Shin Guru Subramanyam Tunable Filters Using Defected Ground Structures at Millimeter-Wave Frequencies Micromachines defected ground structure (DGS) phase change material (PCM) frequency tuning dumbbell u-slot reconfigurable devices tunable filters |
| title | Tunable Filters Using Defected Ground Structures at Millimeter-Wave Frequencies |
| title_full | Tunable Filters Using Defected Ground Structures at Millimeter-Wave Frequencies |
| title_fullStr | Tunable Filters Using Defected Ground Structures at Millimeter-Wave Frequencies |
| title_full_unstemmed | Tunable Filters Using Defected Ground Structures at Millimeter-Wave Frequencies |
| title_short | Tunable Filters Using Defected Ground Structures at Millimeter-Wave Frequencies |
| title_sort | tunable filters using defected ground structures at millimeter wave frequencies |
| topic | defected ground structure (DGS) phase change material (PCM) frequency tuning dumbbell u-slot reconfigurable devices tunable filters |
| url | https://www.mdpi.com/2072-666X/16/1/60 |
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