| 1. |
- Ren, Qiannan, 1994, et al.
(författare)
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An Automotive Polarimetric Radar Sensor With Circular Polarization Based on Gapwaveguide Technology
- 2024
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Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480 .- 1557-9670. ; 72:6, s. 3759-3771
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Tidskriftsartikel (refereegranskat)abstract
- This article presents a novel design of an automotive polarimetric radar sensor with circular polarization (CP) at 77 GHz band based on gap waveguide technology. The proposed design employs a multiple-input multiple-output (MIMO) configuration with single-CP TX antennas and dual-CP RX antennas, enabling the acquisition of sufficient polarimetric information while reducing the number of transmitters (TXs) by half. Gapwaveguide technology is utilized for the implementation of the multilayer waveguide front-end. Series-fed septum polarizers are employed for the antenna design with low-profile characteristics. Measurement results indicate that the antenna elements enable a high level of cross-polarization across the field of view (FoV). Integration of the waveguide front-end with RF boards is achieved using gap waveguide packaging techniques. Static measurements were conducted on common scattering objects to evaluate the sensor’s performance. Polarimetric rotation signatures of the objects were acquired from the measurements, demonstrating the sensor’s potential for use in object identification tasks. Dynamic measurements were performed to evaluate the sensor’s Doppler response. The assessments indicate a high level of accuracy, confirming the effectiveness of the proposed sensor in analyzing dynamic movements. Overall, the proposed polarimetric radar sensor provides persuasive evidence that gap waveguide technology is a highly promising candidate for the realization of advanced automotive radar front-ends.
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| 2. |
- Zang, Zhaorui, 1994, et al.
(författare)
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77-GHz Fully Polarimetric Antenna System With Compact Circularly Polarized Slots in Gap Waveguide for Automotive Radar
- 2024
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Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 72:7, s. 5578-5588
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Tidskriftsartikel (refereegranskat)abstract
- A fully polarimetric antenna system, designed using ridge gap waveguide (RGW) technology, is proposed, fabricated, and experimentally validated based on circularly polarized slots. The proposed slot element, not only plays a role as a radiator but also works as a polarizer. Its geometry is very compact with aperture dimensions of 0.44 λ 0 × 0.44 λ 0 and a profile depth of 0.64 λ 0 . The proposed antenna system has full circular polarizations at both the transmitter (Tx) and receiver (Rx) and comprises four layers with the ability to directly integrate into a radar front-end. High port isolation (≥ 35 dB) between adjacent Rx channels is achieved by using thin decoupling walls and dummy elements to suppress mutual couplings. The measured results show an excellent field of view (embedded axial ratio ≤ 3 dB) in the azimuth plane, with about ±60° at Rx and ±50° at Tx. The antenna system is engineered for low radar cross-section target detection and offers suppression of environmental noise. Experimental evaluation of the integrated radar module shows good agreement between simulation and measurement results. The work offers potential applications of such antenna systems in automotive radar systems, especially where polarization diversity and environmental robustness are required.
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| 3. |
- Ren, Qiannan, 1994, et al.
(författare)
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A Dual Circularly Polarized Array Antenna for Ka-Band Satellite Communications
- 2021
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Ingår i: 2021 International Symposium on Antennas and Propagation, ISAP 2021.
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Konferensbidrag (refereegranskat)abstract
- This work presents a dual circularly polarized 8-by-8 array antenna using inbuilt polarizers for satellite communications. The design consists of five metal layers, including two feeding layers for the dual circular polarizations and a polarizer layer that utilizes a pair of sector cavities as phase delay elements for each sub-array. Two corporate feeding networks using folded E-plane and H-plane T-junctions are proposed to excite the radiating elements. Simulated results of the array antenna have shown that the axial ratios are less than 1 dB from 29 to 31 GHz for both polarizations. The realized gains for both polarizations are larger than 25 dBi at center frequency.
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| 4. |
- Ren, Qiannan, 1994
(författare)
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Advanced automotive radar front-end based on gapwaveguide technology
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The pursuit of higher levels of autonomous driving necessitates the utilization of advanced radar sensors that possess improved environmental perception capabilities. Consequently, next-generation automotive radars require sophisticated antenna systems with high efficiency, thereby making waveguide antennas a more viable choice. In this context, it has been observed that gapwaveguides exhibit superior performance in comparison to traditional waveguides, particularly in terms of assembly reliability, when employed in the development of multi-layer waveguide antennas. Within the scope of this thesis, the primary objective is to comprehensively explore the design of front-ends for cutting-edge automotive radar sensors by leveraging the potential of gapwaveguide technology. The initial aspect of this thesis involves an exploration of integration techniques capable of achieving high performance in waveguide-based RF front-ends. In particular, the thesis introduces novel vertical gapwaveguide-to-microstrip transitions that facilitate the integration of RF front-ends featuring multi-layer configurations. Furthermore, this thesis introduces radar transceivers equipped with built-in waveguide-to-microstrip transitions, known as launcher-in-package, along with an imaging radar antenna featuring customized interconnections explicitly designed utilizing gapwaveguide technology to interface with the transceivers. Secondly, in light of the utilization of radar sensors incorporating orthogonal dual polarizations on the transmitting and/or receiving ends, an opportunity arises to acquire polarimetric information from the surrounding environment, thereby representing a promising advancement in the realm of autonomous driving. This thesis presents novel antenna designs based on gapwaveguide technology for polarimetric radar sensors. An 8$\times$8 planar array utilizing double grooved circular waveguide polarizers is introduced, specifically designed for fixed beam, high gain polarimetric sensing applications. In addition, this thesis presents a polarimetric radar sensor that utilizes a MIMO configuration featuring single-CP transmitting antennas and dual-CP receiving antennas. The antenna design incorporates series-fed septum polarizers, which offer low-profile characteristics. In summary, this thesis undertakes a comprehensive investigation into the designs of advanced automotive radar front-ends utilizing gapwaveguide technology. The study explores the advancements in terms of integration techniques and polarimetric capability, demonstrating the potential of gapwaveguide technology for the practical implementation of waveguide-based RF front-ends. The utilization of such front-ends can significantly enhance the capabilities of autonomous driving systems.
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| 5. |
- Ren, Qiannan, 1994, et al.
(författare)
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Dual-Circularly Polarized Array Antenna Based on Gap Waveguide Utilizing Double-grooved Circular Waveguide Polarizer
- 2022
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Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 70:11, s. 10436-10444
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a dual-circularly polarized array antenna based on gap waveguide technology operating at E band. Double-grooved circular waveguide polarizers that utilize two annulus grooves placed at 45° and 135° offset from both excitation ports are used in this work. The operating principles of the polarizer are analyzed. Multi-layer design using gap waveguide is implemented on the basis of the polarizer. The antenna consists of six layers, including three layers for the feeding networks, one layer for the polarizer, one layer of back cavity and another layer of radiating grid. A 2×2 unit cell is proposed firstly and employed to realize a 8×8 planar array. Corporate feeding networks that use compact E-plane T-junctions and H-plane T-junctions are proposed. The antenna has been fabricated and verified by measurements. The measured results of S-parameters agree well with the simulation and show that reflection coefficients are better than -10 dB for both circular polarizations from 76 to 81 GHz. The measured isolation between the input ports is larger than 25 dB in the operating band. The far-field measurements show that the antenna has realized gain larger than 24 dBi and axial ratios less than 1.5 dB from 76 to 81 GHz at boresight direction.
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| 6. |
- Ren, Qiannan, 1994, et al.
(författare)
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Gapwaveguide Automotive Imaging Radar Antenna with Launcher in Package Technology
- 2023
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Ingår i: IEEE Access. - 2169-3536 .- 2169-3536. ; 11, s. 37483-37493
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Tidskriftsartikel (refereegranskat)abstract
- A 77 GHz gapwaveguide radar antenna system with launcher-in-package (LiP) technology is presented in this paper for automotive imaging applications. Firstly, state-of-the-art LiP technology integrated with radar transceivers is proposed. The transceivers are equipped with waveguide interfaces for RF connection, enabling direct integration with waveguide antennas. Robust interconnects for coupling transceivers to waveguide antennas with non-galvanic contacts are proposed using gapwaveguide packaging technology. A simultaneous multi-mode imaging radar system using 4 cascaded aforementioned transceivers is introduced. Designated antenna elements of the system are realized by slot arrays with center-fed ridge gapwaveguides. Ultimately, the imaging radar antenna has a top radiating slot layer, a middle distribution layer and a bottom interconnect layer capable of accommodating 4 LiP radar transceivers with considerable assembly tolerance which is really one of the key aspects for commercial automotive radar applications. Input matching and radiation patterns of the antenna are verified by measurement. The results indicate that the proposed gapwaveguide imaging radar antenna in conjunction with the novel LiP packaging is able to serve the radar system properly. To the best of the authors’ knowledge, the proposed gapwaveguide antenna system is the first imaging radar antenna system ever developed for LiP components. This work provides a compact, high-efficiency and cost-effective solution for the integration of complex radar systems with waveguide antennas.
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| 7. |
- Ren, Qiannan, 1994, et al.
(författare)
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Millimeter-Wave Vertical Transitions between Ridge Gap Waveguides and Microstrip Lines for Integration of MMIC with Slot Array
- 2021
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Ingår i: 15th European Conference on Antennas and Propagation, EuCAP 2021.
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Konferensbidrag (refereegranskat)abstract
- This paper presents two low-loss vertical transitions between ridge gap waveguides and microstrip lines. The transitions can be utilized as packaging techniques for system level integration of MMICs with waveguide components such as slot array antennas. Both vertical transitions feature microstrip lines being the bottom layer but facing opposite directions. The first vertical transition consists of a microstrip line facing upwards with a patch in the end. Simulation results show that the reflection coefficient is better than -15 dB from 74 to 82 GHz. The second transition of microstrip line facing downwards features E-plane probe with back-short cavity surrounded by periodic pins. Simulation results show that the reflection coefficient is better than -15 dB from 71 to 86 GHz. Comparing with other same layer transitions, the vertical solutions provide more flexibility for the routing of antenna feeding line and have the ability of implementing a more compact design.
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| 8. |
- Ren, Qiannan, 1994, et al.
(författare)
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Novel Integration Techniques for Gap Waveguides and MMICs Suitable for Multilayer Waveguide Applications
- 2022
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Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480 .- 1557-9670. ; 70:9, s. 4120-4128
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Tidskriftsartikel (refereegranskat)abstract
- This article discusses three integration and packaging techniques for gap waveguides and monolithic microwave integrated circuits (MMICs) suitable for multilayer waveguide applications. Two vertical transitions between microstrips and ridge gap waveguides (RGWs) are presented. The first vertical transition connects RGW to a microstrip line from the top where a rectangular patch has been used. Measured results of the transition in a back-to-back structure show that the reflection coefficient is better than $-$ 10 dB from 75 to 83 GHz, and the insertion loss for a single transition over the frequency band is 0.65–0.85 dB. The second vertical transition connects RGW to a microstrip line from the back by a slot in the ground plane. Measured results of the transition in a back-to-back structure show that the reflection coefficient is better than $-$ 10 dB from 69 to 86 GHz, and the insertion loss for a single transition is 0.65–1 dB over the frequency band. Commercially available E-band MMIC amplifiers are integrated with RGWs using the two proposed transitions. Moreover, for the very first time, the integration of MMIC with inverted microstrip gap waveguide (IMGW) is realized by a compact packaging structure that utilizes bond wires and capacitive pads. All the three active integrations are consistent with the passive measurements in terms of operational bandwidth, losses, amplifier gain flatness, and unwanted resonance suppression.
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| 9. |
- Ren, Qiannan, 1994
(författare)
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Towards an Advanced Automotive Radar Front-end Based on Gap Waveguide Technology
- 2022
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis presents the early works on dual circularly polarized array antenna based on gap waveguide, also microstrip-to-waveguide transitions for integration of automotive radar front-end. Being the most widely used radar antenna, PCB antenna suffers from dielectric loss and design flexibility. Next generation automotive radars demand sophisticated antenna systems with high efficiency, which makes waveguide antenna become a better candidate. Over the last few years, gap waveguide has shown advantages for implementation of complicated antenna systems. Ridge gap waveguides have been widely used in passive gap waveguide components design including slot arrays. In this regard, two transitions between ridge gap waveguides and microstrip lines are presented for the integration with gap waveguide antennas. The transitions are verified in both passive and active configuration. Another work on packaging techniques is presented for integration with inverted microstrip gap waveguide antennas. Systems utilizing individual linear polarization (LP) that lack polarimetric capabilities are not capable of measuring the full scattering matrix, thus losing information about the scenery. To develop a more advanced radar system with better detectability, dual circularly polarized gap waveguide slot arrays for polarimetric radar sensing are investigated. An 8×8 planar array using double grooved circular waveguide polarizer is presented. The polarizers are compact in size and have excellent polarization properties. Multi-layer design of the array antenna benefits from the gap waveguide technology and features better performance. The works presented in this thesis laid the foundation of future works regarding integration of the radar front end. More works on prototyping radar systems using gap waveguide technology will be presented in future publications.
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