| 1. |
- Alex-Amor, Antonio, et al.
(författare)
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Glide-Symmetric Metallic Structures With Elliptical Holes for Lens Compression
- 2020
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Ingår i: IEEE transactions on microwave theory and techniques. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9480 .- 1557-9670. ; 68:10, s. 4236-4248
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Tidskriftsartikel (refereegranskat)abstract
- In this article, we study the wave propagation in a metallic parallel-plate structure with glide-symmetric elliptical holes. To perform this study, we derived a mode-matching technique based on the generalized Floquet theorem for glide-symmetric structures. This mode-matching technique benefits from a lower computational cost since it takes advantage of the glide symmetry in the structure. It also provides physical insight into the specific properties of Floquet modes propagating in these specific structures. With our analysis, we demonstrate that glide-symmetric structures with periodic elliptical holes exhibit an anisotropic refractive index over a wide range of frequencies. The equivalent refractive index can be controlled by tuning the dimensions of the holes. Finally, by combining the anisotropy related to the elliptical holes and transformation optics, a Maxwell fish-eye (MFL) lens with a 33.33% size compression is designed. This lens operates in a wideband frequency range from 2.5 to 10 GHz.
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| 2. |
- Ebrahimpouri, Mahsa, et al.
(författare)
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A bespoke lens for a slot log-spiral excitation
- 2018
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Ingår i: IET Conference Publications. - : Institution of Engineering and Technology.
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Konferensbidrag (refereegranskat)abstract
- In this paper, a bespoke lens has been designed for a slot log-spiral excitation. The performance of this lens is compared with a conventional hyper-hemispherical lens. Using the bespoke lens methodology, the specific electromagnetic properties of the slot log-spiral excitation are obtained and its phase fronts are transformed to flat phase fronts by a QCTO (quasi-conformal transformation optics) technique. The performance of the lenses is evaluated with the radiation properties. The bespoke lens produces an improvement in terms of directivity and side lobe levels.
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| 3. |
- Ebrahimpouri, Mahsa, et al.
(författare)
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Bespoke Lenses Based on Quasi-Conformal Transformation Optics Technique
- 2017
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Ingår i: IEEE Transactions on Antennas and Propagation. - : IEEE. - 0018-926X .- 1558-2221. ; 65:5, s. 2256-2264
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, a systematic method to design a quasioptimum lens profile based on quasi-conformal transformation optics technique for a given excitation is presented. This method is applied to a number of conventional antennas, such as an aperture and a log-spiral slot. In all these configurations, an increase of the directivity is observed. Furthermore, using this method, a quasi-optimum graded index lens for a broadband enhanced leaky slot excitation is designed and the results are compared with a hyperhemispherical lens with and without matching layers. Our proposed methodology demonstrates to be able to increase the directivity, to reduce the sidelobes and the cross polarization in a broad bandwidth from 20 to 70 GHz. Due to the continuously changed dielectric constant of the lens profile, reflections are also reduced considerably inside the lens.
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| 4. |
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| 5. |
- Ebrahimpouri, Mahsa, et al.
(författare)
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Contact-less Measurement by Using Glide-symmetric Holes on Flanges
- 2018
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Ingår i: 2018 12TH INTERNATIONAL CONGRESS ON ARTIFICIAL MATERIALS FOR NOVEL WAVE PHENOMENA (METAMATERIALS). - : IEEE. ; , s. 105-107
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Konferensbidrag (refereegranskat)abstract
- We present a cost-effective solution for contact-less measurement of waveguiding structures at high frequencies. Drilling glide-symmetric holey EBG (electromagnetic band gap) on the flanges, the leakage caused by undesired air-gaps, by the result of human mistakes or instrumental errors, between the flanges can be minimized considerably and contact-less measurement becomes possible.
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| 6. |
- Ebrahimpouri, Mahsa, et al.
(författare)
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Cost-Effective Gap Waveguide Technology Based on Glide-Symmetric Holey EBG Structures
- 2018
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Ingår i: IEEE transactions on microwave theory and techniques. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9480 .- 1557-9670. ; 66:2, s. 927-934
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Tidskriftsartikel (refereegranskat)abstract
- We present a novel electromagnetic bandgap (EBG) structure, which can be used to manufacture low-cost waveguiding structures at high frequencies. The unit cell of the proposed EBG consists of glide-symmetric holes in parallel plate waveguide. Using this unit cell in groove gap waveguide technology has a number of advantages over pin-type EBG at high frequencies, such as acquiring higher accuracy because of larger periodicity as well as an easier and cheaper manufacturing process. The performance of the proposed waveguiding structure is demonstrated using both a straight and a double 90 degrees bent lines through simulation and measurement.
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| 7. |
- Ebrahimpouri, Mahsa, et al.
(författare)
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Design Guidelines for Gap Waveguide Technology Based on Glide-Symmetric Holey Structures
- 2017
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Ingår i: IEEE Microwave and Wireless Components Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1531-1309 .- 1558-1764. ; 27:6, s. 542-544
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Tidskriftsartikel (refereegranskat)abstract
- The behavior of a glide-symmetric holey periodic structure as electromagnetic bandgap is studied in this letter. A number of numerical simulations have been carried out in order to define the importance of each constituent parameter of the unit cell. Our proposed structure finds potential application in antennas and circuits based on gap waveguide technology for the millimeter band. The experimental verifications confirm the effects previously analyzed with the numerical studies.
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| 8. |
- Ebrahimpouri, Mahsa, et al.
(författare)
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Design of microwave components in groove gap waveguide technology implemented by holey EBG
- 2017
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Ingår i: 2017 11th European Conference on Antennas and Propagation, EUCAP 2017. - : Institute of Electrical and Electronics Engineers (IEEE). - 9788890701870 ; , s. 746-748
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Konferensbidrag (refereegranskat)abstract
- In this paper, the feasibility of the implementation of microwave components in groove gap waveguide technology by glide-symmetry holey EBG is discussed. Using this technology, microwave components and antennas which were previously designed for hollow metallic waveguides can be manufactured in a cost-effective way at high frequencies. To show the viability of the proposed solution a phase shifter and a mode converter are designed as examples of typical components for antenna systems.
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| 9. |
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| 10. |
- Ebrahimpouri, Mahsa, et al.
(författare)
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Experimental Validation of a Bespoke Lens for a Slot Log-Spiral Feed
- 2020
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Ingår i: IEEE Antennas and Wireless Propagation Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1536-1225 .- 1548-5757. ; 19:4, s. 557-560
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Tidskriftsartikel (refereegranskat)abstract
- In this letter, we experimentally validate the concept of bespoke lenses for the specific design of a log-spiral feed. Bespoke lenses are designed using the concept of quasi-conformal transformation optics (QCTO) to enhance the radiation properties for a given feeding. Our experimental results demonstrate that the antenna with its bespoke lens has higher gain, lower cross polarization, lower sidelobes, and lower axial ratio than that with a conventional hyperhemispherical lens.
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