Exploring the Properties of Reverberation Chambers in the THz Range: A Pilot Study

Abstract: The rapid evolution of wireless communication technology and the emergence of 6G have led to the exploration of new segments of the electromagnetic spectrum, specifically the THz region. These high frequencies promise exceptionally high data rates, yet they also introduce substantial technical challenges.
One primary challenge involves measurement techniques, encompassing component design, instrument manufacturing, and the creation of practical testing environments suitable for these frequencies. In this paper, we focus on employing reverberation chambers as testing environments within the THz region. Firstly, we examine the chamber’s characteristics, particularly addressing losses up to 220 GHz. Subsequently, we present the hardware components and introduce a dedicated new mode stirrer designed for operation at these frequencies. The paper also offers insights and establishes a theoretical foundation for loss calculations within the reverberation chamber at high frequencies.
Keywords: Reverberation Chamber, Terahertz (THz) Frequencies, Spurious Emission, 5G, 6G, OTA
Piblished in: European Conference on Antennas and Propagation EuCAP2024, Glasgow, UK EuCAP2024
Date of Publication: Mar 2024

Exploring the Properties of Reverberation Chambers in the THz Range: A Pilot Study

Abstract: In this paper, two analytical techniques for computing the input impedance of cables are introduced. Given the pivotal role of the SMA connector in altering cable input impedance, it is essential to account for the significant effect of the connector in the impedance calculations. This effect is addressed through the use of two models for the connector, namely the circuit model and the cascade model. These analytical techniques can be applied to various cables, provided that the impedance of the cable up to the connector is known, and the impact of the connector on the input impedance is appropriately considered by the models.
Keywords: Cable, Common-mode, EMC, EMI, Input impedance, circuit model
Piblished in: EMC Japan/Asia-Pasific International Symposium on Electromagnetic Compatibility
Date of Publication: Jan 2024

A W-band Quasi-Optical Array Antenna Feeding Network with High Taper Efficiency Using Optimal Ridge Excitation of an H-Plane Sectoral Waveguide

Abstract: A novel H-plane quasi-optical (QO) feeding network for linear (sub-)array gap waveguide (GWG) antennas intended for beam-steering applications at W-band is presented. The QO feed comprises an H-plane sectoral GWG excited by an input stepped ridge gap waveguide (RGW) and transitioned to an overmoded rectangular groove gap waveguide (GGW) section, the latter being terminated with an array of RGW output probes. This work’s key challenge and novelty is engineering the desired modal content in the QO structure for uniform amplitude excitation of array elements to enhance antenna gain with a low insertion loss. This was addressed by (i) realizing an optimal multi-mode excitation of the sectoral GWG and (ii) a proper phasing of a rich modal spectrum of the output overmoded GGW. An eigenmode-based semi-analytic approach was developed to investigate the impact of an input ridge length on the excited modal content and was shown to predict optimal results close to full-wave simulations. The demonstrated QO feed concept, applied to a 20-element array design, significantly outperforms existing solutions by achieving a 97% amplitude taper efficiency and showing less than 0.4 dB insertion loss over a 21% relative bandwidth (85–105 GHz).
Keywords:—quasi-optical feed, array antenna, gap waveguide
Piblished in: IEEE Antennas and Wireless Propagation Letters
Date of Publication: Dec. 2023

A Compact and Wideband MMIC to Ridge Gap Waveguide Contactless Transition for Phased Array Antenna Front-Ends

Abstract: A concept of a contactless in-line transition between a monolithic microwave integrated circuit (MMIC) and a ridge gap waveguide (RGW) is proposed and investigated at W-band. The transition employs an E-plane waveguide bifurcation obtained by mounting a GaAs MMIC on a supporting PCB in the opening of an RGW top metal lid. Designed this way, multiple contactless transitions can be placed in a row with an electrically small spacing that makes the transition idea suitable for array antenna front-ends. A transition equivalent circuit is constructed employing a single-mode transmission line model, which is verified through a full-wave simulation. An (85–105) GHz transition design is then developed and experimentally investigated in the back-to-back configuration indicating a (0.5–0.75) dB transition insertion loss. Finally, the performance of a 1-bit phase shifter MMIC, integrated into the RGW using two proposed transitions, is demonstrated.
Keywords:Contactless transition, MMIC, gap waveguide, array antennas
Piblished in: IEEE Antennas and Wireless Propagation Letters
Date of Publication: Dec 2023

Wideband Reflection-Type p-i-n Diode Phase Shifters in GaAs MMIC Technology at W-Band

Abstract: In this paper, we report on developing W-band GaAs p−i−n diode phase shifters (PSs) with a wideband phase and amplitude response. The PSs employ the reflection-type architecture with reflective loads providing discrete phase tunability through diode dc control. We address the design challenge of having a stable phase shift and a minimal insertion loss imbalance for the diodes with a relatively low commutation quality factor at high millimeter-wave frequencies. Two PS examples, namely 180- and 90-degree bits, are designed for the targeted (85-105) GHz operating band. The circuits were fabricated in the commercial PIN-pHEMT GaAs process with 8×8μm2p−i−n diodes. Both simulated and measured results are in good agreement demonstrating wideband frequency performance.
Keywords: Time-frequency analysis, Correlation, Statistical analysis, Reverberation chambers, Loading, Estimation, Europe
Piblished in: 2023 18th European Microwave Integrated Circuits Conference (EuMIC)
Date of Publication: Oct 2023

A Multivariate Approach for the Effective Sample Size of Frequency Stirring

Abstract: We introduce a new method for the estimation of the effective sample size due to frequency stirring in reverberation chambers. The method is based on a multivariate approach, which is able to estimate the single-level correlation of frequency stirring, based on two-, or many-levels correlations due to concurrent stirring mechanisms. We confront the estimations of the effective sample size due to frequency stirring from our method with theoretical predictions. The comparison with theory, shown here for the first time, allows for a deeper confidence on the validity of our proposed method. The agreement is shown for different types of reverberation chambers, at different loading conditions for wide frequency ranges.
Keywords: Time-frequency analysis, Correlation, Statistical analysis, Reverberation chambers, Loading, Estimation, Europe
Piblished in: 2023 International Symposium on Electromagnetic Compatibility – EMC Europe
Date of Publication: Oct 2023

On the Relation Between Field Correlation and Field Uniformity in Reverberation Chambers

Abstract: Analytical formulas and Monte Carlo simulations are here offered in order to investigate if, and up to which extent, residual correlation of measured electric field (E-field) magnitude affects or influences field uniformity in a reverberation chamber (RC). Field uniformity is evaluated according to the standard IEC 61000-4-21 [1]. It is shown that correlation associated with mechanical stirrer worsens field uniformity, while spatial correlation and correlation between orthogonal E-field components may improve (i. e., reduce the numbers quantifying) field uniformity.
Keywords: Correlation, Monte Carlo methods, Reverberation chambers, Electric variables measurement, IEC Standards, Electric fields, Standards
Piblished in: 2023 XXXVth General Assembly and Scientific Symposium of the International Union of Radio Science (URSI GASS)
Date of Publication: Oct 2023

Analysis of Concurrent and Correlated Stirring Mechanisms in Reverberation Chambers

Abstract: A new multivariate statistical analysis is proposed to derive the estimates of effective sample sizes of reverberation chamber (RC) measurement data. Concurrent correlation effects, related to different and simultaneously acting stirring mechanisms, are taken into account and individually quantified. The mean and variance of correlated measurement data are also estimated, as well as the variance of the grand mean. The analysis is independent on the parent probability distributions. Formulae are obtained through a step-by-step derivation, stemming from basic statistical principles and general assumptions, which are deemed to be applicable to the correlation structures of RC measurement data. Experiments and comparison with closed-form predictions confirm the validity and generality of the analysis.
Keywords:Measurement uncertainty, Size measurement, Frequency measurement, Autocorrelation, Standards, Probability density function, Volume measurement
Piblished in: IEEE Transactions on Electromagnetic Compatibility
Date of Publication: Apr 2023

Uncertainties in determining the gain-curves of a
Standard Gain Horn Antenna from 90 GHz to 140 GHz

Abstract: This paper examines the validity of employing the Naval Research Laboratory’s (NRL) on-axis gain calibration curves as a standard reference, as specified in the commercial Standard Gain Horn (SGH) antenna datasheets, for the frequency range of 90 GHz to 140 GHz for antenna gain measurements. We present a comprehensive analysis of the on-axis gain calibration curve characteristics and the dimensions of the SGH antenna by employing three different dimensional measurement techniques and quantifying the discrepancies in comparison to the on-axis calibration curve found in datasheets. Additionally, we demonstrate that inaccuracies in the dimensional data provided in the commercial SGH
antenna datasheet can lead to a gain deviation of ±1 dB from the anticipated gain. We validate the on-axis gain curves obtained from simulation by conducting measurements in a spherical anechoic chamber
Keywords: Anechoic chamber, measurements, mm-wave, on-axis gain curve, Standard Gain Horn (SGH)
Conference: The 18th European Conference on Antennas
and Propagation will be held on March 17-22 March 2024, in Glasgow, Scotland
Date of Publication: Dec 2023

Efficient Integral-Equation Methodology for Full-Wave
Signal Integrity Analysis on the IBM Plasma Substrate Benchmark

Abstract: A full-wave simulation is conducted on the IEEE plasma package benchmark problem using an integral equation-based solver. This approach offers two distinct advantages over conventional Finite-Element Method (FEM) based solvers, namely the use of a surface-based mesh instead of a volumetric representation and excellent efficiency for largescale structures such as IC packages. With its large quantity of geometries, the benchmark serves as a test case for validating the performance of full wave solvers on integrated circuits
Keywords: Packaging Benchmark Suite, Integral Equation Solver, Integrated Circuit (IC)
Conference: IEEE Electrical Design of Advanced Packaging and Systems (EDAPS) December 12-14, 2023
Date of Publication: Sept 2023

Contactless measurement of a D-band on-chip antenna
using an integrated reflective load switch

Abstract: A novel measurement setup is proposed for the contactless characterization of on-chip antennas. A D-band patch antenna is fabricated on a 100 μm-thick GaAs substrate and is monolithically integrated with a reflective load switch to allow for fast electronic control of the antenna port termination. The antenna under test is illuminated by a reference antenna in the anechoic chamber after which the impedance and gain of the patch antenna are reconstructed from the change in backscat- tered field due to different port terminations. In our experiment, the over-the-air reconstructed antenna input impedance exhibits a frequency shift of less than 1% with respect to the (non-ideal) on-wafer probe measurement in the 115–130 GHz frequency range. Furthermore, the measured realized gain of 0.9 ± 0.5 dBi is close to the simulated one of 1.1 dBi.
Keywords: quasi-optical feed, array antenna, gap
waveguide
Published in: IEEE Antennas and Wireless Propagation Letters
Date of Publication: Sept 2023

Integral Equation-Based Solver for the Simulation of
Integrated Circuit Packages

Abstract: A full wave simulation using an integral equation based solver on the IEEE plasma package benchmark problem is performed. The integral equation approach offers advantages over traditional Finite-Element Method (FEM) solvers, as it uses a surface-based mesh and shows excellent efficiency for large-scale structures like IC packages. With its large amount of geometries, The benchmark is used as a test case to validate the full wave solvers on integrated circuits.
Keywords: Packaging Benchmark Suite, Integral Equation Solver, Integrated Circuit (IC)
Conference: 2023 EPEPS Conference
Date of Publication: Sept 2023

Scan-Loss Compensation for Full-Azimuth Multi-Facet Phased
Array Antennas

Abstract: An approach to compensate scan losses displayed by full-azimuth multifacet phased arrays is proposed in this article. This approach is based on a constructive superposition of scanned beams from adjacent array panels resulting in enhanced composed coverage. Said constructive superposition is achieved by coordinating the insertion phase shifts applied at the array element level. Special attention is given to panel arrays arranged in equilateral triangle and square prisms. The benefits of the proposed beamforming approach are validated by full-wave simulations, as well as passive antenna measurements taken on physical prototypes. The achieved improvement in equivalent isotropically radiated power (EIRP) excessively compensates for the experienced scan loss and reaches 6 dB at the maximal scan angles. An additional advantage of the developed methodology consists in the mitigation of the composed beam squint at wide scan angles.
Keywords: Equivalent isotropically radiated power (EIRP), far-field superposition,
full-azimuth phased arrays, scan loss
Published in: IEEE Transactions on Antennas and Propagation
Date of Publication: Dec 2022

Automated Creation of Reusable Generators for Analog IC Design with the Intelligent IP Method

Abstract: Procedural generators are often proposed for analog IC design automation. They promise to encapsulate designer knowledge and intellectual property (IP) data in a deterministic and reusable way. While recent developments claim to have proven this, one question remains: How to create generators efficiently and integrate them in an automated design flow? A major challenge for generators is the trade-off between initial implementation effort, reusability, and acceptance. This raises further questions on the role of the generator supplier: Who should spend the effort implementing and maintaining generator IP? Which interfaces and standards can be used to implement and integrate them into common design environments? In order to address these challenges, we propose a combination of pre-defined generators for basic building
blocks at lower hierarchy levels with automatic creation of generators using place and route templates for more complex circuits. The paper demonstrates the successful application of this flow to an OTA design and discusses the required implementation efforts, quality of the generated results and potential future developments.
Keywords: analog; layout; generators; templates; design
automation; reuse; soft IP
Conference:  DVCon Europe 2022 (dvcon-europe.org)
Date of Publication: Dec 2022