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This article presents the design of a planar MIMO (Multiple Inputs Multiple Outputs) antenna comprised of two sets orthogonally placed 1 × 12 linear antenna arrays for 5G millimeter wave (mmWave) applications. The arrays are made of probe-fed microstrip patch antenna elements on a 90 × 160 mm2 Rogers RT/Duroid 5880 grounded dielectric substrate. The antenna demonstrates S11 = −10 dB impedance bandwidth in the following 5G frequency band: 24.25–27.50 GHz. The scattering parameters of the antenna were computed by electromagnetic simulation tools, Ansys HFSS and CST Microwave Studio, and were further verified by the measured results of a fabricated prototype. To achieve a gain of 12 dBi or better over a scanning range of +/−45° from broadside, the Dolph-Tschebyscheff excitation weighting and optimum spacing are used. Different antenna parameters, such as correlation coefficient, port isolation, and 2D and 3D radiation patterns, are investigated to determine the effectiveness of this antenna for MIMO operation, which will be very useful for mmWave cellphone applications in 5G bands.
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Inverted Scanning Microwave Microscopy of GaN/AlN High-Electron Mobility Transistors
In this paper, an inverted scanning microwave microscope (iSMM) is used to characterize the channel of a gateless GaN/AlN high-electron-mobility transistor (HEMT). Unlike conventional SMM, iSMM allows for 2-port measurements. Unlike conventional iSMM, the present iSMM probe is connected to Port 1 of a vector network analyzer with the HEMT drain and source remain on Port 2. Under different DC biases VGS (applied through the iSMM probe) and VDS (kept constant at 1 V), changes in both reflection coefficient S11 and transmission coefficient S21 are monitored as the iSMM probe scans along the width of the channel, revealing significant nonuniformity. Additionally, changes in S11 and S21 are significant when VGS ≥ −4 V, but insignificant when VGS = −8 V, consistent with the measured threshold voltage at −6 V for a gated HEMT. These results confirm that iSMM can be used to locally modulate the channel conduction of a HEMT while monitoring its RF response, before the actual gate is added. In turn, the nonuniformity measured by the iSMM can be used to diagnose and improve HEMT materials and processes.
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- PAR ID:
- 10542569
- Publisher / Repository:
- IEEE
- Date Published:
- ISBN:
- 979-8-3503-6273-2
- Page Range / eLocation ID:
- 1 to 4
- Subject(s) / Keyword(s):
- Scanning microwave microscope transfer characteristics two-dimensional electron gas GaN HEMT
- Format(s):
- Medium: X
- Location:
- Washington, DC, USA
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1109/ARFTG61196.2024.10660702
