Spherical mm-Wave/THz Antenna Measurement System

IEEE Microw. Wireless Compon. Lett.

Dedic

et al. 2022

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Radar sensing has become very popular over the last two decades, and research has focused on high-bandwidth and high-resolution systems. Due to the steadily increasing center frequency of front-end circuits, on-chip antennas are the preferred choice over PCB antennas and horn antennas when frequencies get close to THz. However, conventional on-chip antennas are severely limited in bandwidth, leading to increased use of wideband and multiresonant on-chip antennas. Besides a more complex design process of multiresonant antennas, they have the disadvantage of a nonconstant dispersive group delay (GD). This reduces the resolution of sensing systems, such as the range resolution and angular resolution of a radar system. In this work, we show how GD affects the imaging properties of a radar system. The measured S-parameter data from a 240-GHz multiresonant antenna are used to generate synthetic intermediate frequency (IF) signals of a rectangular array. Subsequently, simulated 3-D radar images are generated using the backprojection algorithm. These images are compared with those of a nondispersive imaging system. Finally, two compensation methods using a phase correction method and an all-pass filter are explained, and their performance is compared.

Section: Antenna Measurements and Simulation Resultsmentioning

confidence: 99%

The Impact of Group Delay Dispersion on Radar Imaging With Multiresonant Antennas

IEEE Microw. Wireless Compon. Lett.

Dedic

et al. 2022

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“…For the antenna radiation pattern measurement, a spherical wafer antenna measurement system [24] is used. To minimize the chip area overhead, the probing pads are located close to the antenna.…”

Section: Cp Characterization At Mm-wavesmentioning

confidence: 99%

“…Here, two cut-planes are measured, and the φ = 0 • -cut only covers a range of 0 • ≤ θ ≤ 90 • , since smaller angles usually suffer from the shadowing of the probe. Furthermore, the φ = 90 • -cut is limited by • to hinder a collision with the microscope [24]. Since the orthogonal components E φ and E θ of each measurement position are measured in direct subsequence, long-term phase-drift due to temperature variations does not affect the accuracy of the measurement.…”

Section: Mm-wave Antenna Measurementmentioning

confidence: 99%

Bandwidth-Enhanced Circularly Polarized mm-Wave Antenna With On-Chip Ground Plane

IEEE Trans. Antennas Propagat.

Svejda

et al. 2022

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This paper presents a design methodology and a realization of a circularly polarized (CP) antenna for FMCW radar at mm-wave frequencies on-chip, which combines antennas of different resonance frequencies to increase the operation bandwidth and allow for high resolution radar. The antenna consists of four dipoles with an on-chip ground plane operating at two resonance frequencies combined with a matching and feeding network, which enables both a frequency selectivity in advantage for the resonant antenna and radiation of circular polarization. The dipole arms are based on shorted λ/4 resonators, which are enhanced with series capacitances for increased radiation efficiency. A method for the broadband characterization of CP antennas and the measurement results of the designed CP antenna are presented. It is shown that the antenna covers a bandwidth between 220 GHz and 260 GHz, indicating the feasibility of both the measurement method and the antenna concept.

“…The results presented from now on are based on the corrected EC model. For the on-chip antenna measurement, the spherical antenna measurement system presented in [39] was set up to measure the copolarization of the antenna. The measurement setup with the microscope over the wafer chuck and the reference horn antenna is depicted in Fig.…”

Section: On-chip Antenna Measurementsmentioning

confidence: 99%

Equivalent Circuit Model Separating Dissipative and Radiative Losses for the Systematic Design of Efficient Microstrip-Based On-Chip Antennas

Svejda

IEEE Trans. Microwave Theory Techn.

et al. 2021

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This article presents a comprehensive method to efficiently design capacitively enhanced resonant on-chip antennas using an equivalent circuit (EC) model instead of computationally demanding full-wave simulations. To systemize the design process by predicting the radiation efficiency, the input impedance, the current and voltage distributions, and the radiation pattern of the antenna based on an EC, a method to extract both dissipation and radiation mechanisms from full-wave simulation data is described and carried out. Based on this separation of loss mechanisms, an EC-based antenna optimization with respect to the radiation efficiency is conceivably possible. Additional to the EC, which enables this efficient antenna optimization and increases the physical insight in the radiation mechanism, an analytical estimation of key antenna parameters, as the resonant length, is presented. The results from the analytical calculations and the antenna parameters calculated using the EC model are compared with full-wave FDTD simulations and used to discuss the capabilities and limitations of the EC model. Finally, an on-chip antenna of the considered type operating at 290-300 GHz and manufactured with silicon-germanium technology is used to verify the full-wave antenna simulations and the presented approach in general. Index Terms-Antennas' theory and design, equivalent circuit (EC), millimeter-wave and terahertz components, passive component modeling, silicon-germanium (SiGe/Si) technologies. I. INTRODUCTIONT HE need for highly efficient mm-wave on-chip antennas manifests in numerous applications, namely high-resolution radar imaging [1], detailed material characterization [2], and high-data-rate communication [3]. A key parameter to increase the performance of the overall system is reducing the loss contributions of the transducer between the front end and free space, namely the antenna. These loss Manuscript