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1. Mm-Wave Beam Steering Antennas Using Stacked Parallel Plate Lens Antenna Subarrays

   https://doi.org/10.1109/USNC-URSI52151.2023.10237493  

   Jebreil, Omar; Mumcu, Gokhan (July 2023, IEEE)

   A millimeter (mm)-wave beam steering antenna consisting of subarrays of parallel plate lenses is presented for the first time. As compared to a previously reported antenna that utilized subarrays of dielectric slab waveguide lenses, the presented antenna allows to design and control the beamwidth of the radiation pattern in the plane orthogonal to the beam steering plane by stacking the parallel plate lens subarrays. Additionally, full wave simulations of the presented antenna show performance improvements in gain, side lobe level, and field of view in comparison to the previously reported dielectric slab waveguide-based realization. 

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2. Cloaking and Decoupling of Interleaved Microstrip Monopole Arrays at 28 GHz and 39 GHz Using Elliptical Metasurfaces for 5G Wireless Applications

   S. Pawar, S. Mastromatteo (July 2020, 2020 IEEE AP-S/URSI Conference)

   null (Ed.)

   Two tightly spaced, interleaved microstrip monopole antenna arrays operating at microwave frequencies are decoupled by employing mantle cloaking method. We use elliptical metasurfaces specifically tailored for the cross-coupled elements of the distinct arrays and show that by wrapping each antenna element with the metasurface cloak, the undesired cross-coupling between the elements at frequencies 28 GHz and 39 GHz is eliminated, restoring their radiation patterns as if the arrays were isolated from each other. In this paper, the cloaking and decoupling effect is scrutinized and evaluated to improve the functionality of the coupled arrays in terms of their radiation patterns and realized gain, when all the antenna elements are excited simultaneously. Consequently, the monopole antenna arrays, even though placed in close proximity, can radiate independently for a wide range of beam scanning angles. 

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3. Waveguide-fed Antipodal Vivaldi Antenna using an Antipodal Finline Transition

   https://doi.org/10.1109/APUSNCURSINRSM.2018.8608326  

   Molaei, Ali; Martinez-Lorenzo, Jose (July 2018, 2018 IEEE International Symposium on Antennas and Propagation & USNC/URSI National Radio Science Meeting)

   In this paper, a new waveguide-fed Antipodal Vivaldi Antenna (AVA) for mm-wave imaging applications is presented. A waveguide-to-broadside coupled Antipodal finline transition is designed to couple the dominant mode of a WR-12 waveguide into the AVA. The transition provides a wideband and low insertion loss in the entire E-band. A dielectric lens is added in front of the AVA to increase the directivity in theendfire direction of the antenna. The performance of the designed antenna is evaluated in the E-band in terms of its return loss,gain, and radiation pattern. 

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4. Effect of Internal Reflections on the Performance of Lens-Integrated mmW and THz Antennas

   Ozbey, B.; Sertel, K. (March 2018, Applied Computational Electromagnetics Society Symposium)

   Multiple reflections from electrically large hemispherical lens surfaces of lens-integrated antennas are investigated using an iterative Huygens’ integral approach. In particular for mmW- and THz-band applications, double-slot antennas on extended hemispherical high-resistivity Silicon lenses have been widely used due to the high Gaussisicity of their radiation/ reception patterns. Previous studies assumed an electrically-large lens and evaluated the antenna pattern using first-order physical optics approximation. Although this approach is fairly accurate for estimating the radiation pattern of such antennas, the reception pattern and the associated performance of receiving sensors need a more careful consideration due to the relatively large level of internal reflections from the concave boundary of the high index lens. Here, we present an iterative method to compute and study the effects of multiple reflections inside electrically large lenses. The rich nature of quasi-optical wave behavior is demonstrated through several examples corresponding to individual bounces of the incident, reflected, and transmitted waves from a double slot antenna. 

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5. Robotically‐controlled antenna measurement system for millimeter‐wave applications

   https://doi.org/10.1002/mop.32773  

   Matos, Carmen; Humanchuk, Jennifer; Ghalichechian, Nima (December 2020, Microwave and Optical Technology Letters)

   Abstract The characterization of antenna radiation patterns in millimeter‐wave (mmW) bands can be particularly challenging. Due to a small wavelength, minute misplacement of the probe antenna in the order of few millimeters can generate substantial errors in the measured pattern. A highly precise measurement system that incorporates a 6‐axis compact robotic arm is implemented to overcome this challenge. System testing shows a positional accuracy and repeatability of approximately 20 μm or 0.004λ at 60 GHz. After implementation, programming, and testing, the system is used to measure gain patterns on three different mmW antennas. The radiation pattern of a 50–75 GHz standard gain horn antenna demonstrated the accurate measurement at the far‐field using the robotically controlled system. Furthermore, the characterization of the center element pattern of a 60 GHz phased array has shown that the measurements with this system are repeatable and suitable for arrays as well. Additionally, we performed near‐field measurements by successfully characterizing a 40–60 GHz horn antenna with a planar scan. 

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