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Wireless Multi-Port Sensing: Virtual-VNA-Enabled De-Embedding of an Over-the-Air Fixture

T0 review · 3 major / 6 minor · reviewed 2026-08-06 · deepseek-v4-flash

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Pith's one-line read The paper claims that an unknown multi-port circuit's full scattering matrix can be recovered over the air, with no assumptions about the wireless environment beyond linearity, passivity, time-invariance, and reciprocity, by…

desk verdict Solid experimental first for OTA multi-port load impedance sensing; the 'unambiguous' claim outruns the theory, but the work deserves a real referee. read the letter →

arxiv 2507.12909 v1 pith:HFS3Z7LV submitted 2025-07-17 physics.app-ph eess.SP

Philipp del Hougne This is my paper · ORCID
classification physics.app-pheess.SP
keywords wirelesssensingbackscattermodulationscatteringmatrixestimationVirtualVNAde-embeddingmutualcouplingreverberationchamberRFID
verification ladder T0 review T1 audit T2 compute T3 formal

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The reading

The paper claims that the full scattering matrix of a passive, reciprocal, time-invariant multi-port circuit—the 'DUT'—can be recovered remotely and unambiguously from over-the-air measurements alone, without any assumptions about the wireless propagation environment or the antennas beyond linearity, passivity, time-invariance, and reciprocity (and that every port is lumped and monomodal). The method does this by treating the wireless channel plus all antennas as a fixed 'OTA fixture' between the reader and the DUT, characterizing that fixture with a known tunable load network using the Virtual VNA technique, and then de-embedding the fixture from a measurement taken with the DUT attached. A sympathetic reader should care because this fills a long-standing gap: prior multi-port backscatter sensing recovered only magnitudes or proportions of load admittance entries, required a free-space channel, or needed perfectly known antennas. Proof-of-concept experiments at 2.45 GHz recover 1-port and 5-port DUTs in a reverberation chamber with high accuracy, and the benchmarking shows that the load-network hardware requirements relax when more than one DUT port is present.

What carries the argument

The load-bearing object is the multi-port scattering relation between the measured accessible-antenna matrix $S$, the fixed OTA fixture block $S^F$, and the termination $S^L$ (the tunable load network or the DUT): $$S = S^F_{AA} + S^F_{AS}\left((S^L)^{-1} - S^F_{SS}\right)^{-1} S^F_{SA}.$$ The Virtual VNA technique carries the argument: it estimates the scattering parameters of ports that are not directly connected to the VNA by terminating those ports with known individual loads and coupled two-port loads, and it supplies both closed-form and gradient-descent estimation procedures. A procedural novelty is that random load configurations mixing individual loads and coupled loads, each used at least once, allow the number of distinct individual loads to be reduced from three to two when $N_S>1$.

What would settle it

Run the same three-step procedure on a known multi-port device whose ports are deliberately not monomodal at 2.45 GHz (for instance a radiating antenna-array DUT), then compare the recovered scattering matrix with a direct VNA measurement; any deviation beyond measurement noise would show that the monomodal-port assumption is necessary.

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Extended reading notes

Core claim

The central result is an unambiguous over-the-air estimate of an unknown reciprocal DUT's scattering matrix $S_D$, obtained in three steps. First, with the not-directly-accessible antennas terminated by a known tunable load network, measurements of the scattering matrix $S$ seen at the accessible antennas are fed into the Virtual VNA estimation procedure to recover the OTA fixture's scattering matrix $S_F$ up to a sign ambiguity on $S^F_{AS}=(S^F_{SA})^\top$ that is operationally harmless because it cancels in the de-embedding relation. Second, the DUT replaces the tunable load network and $S$ is measured again. Third, a gradient-descent fit of the relation $S = S^F_{AA} + S^F_{AS}\left((S^L)^{-1} - S^F_{SS}\right)^{-1} S^F_{SA}$ to the second measurement yields the sought-after $S_D$. Experimental results with 1-port and 5-port DUTs in a reverberation chamber at 2.45 GHz recover the full scattering matrices with small mean-squared errors, while the simplified benchmarks degrade substantially.

Load-bearing premise

The load-bearing premise is that the unknown device interacts with the wireless environment only through its lumped, single-mode ports; if the device itself radiates through its own antenna modes, the model and the de-embedding step break down.

Editorial extensions

If this is right

  • Multi-port sensor networks and RFID grids can have their full load impedance matrices read wirelessly, including off-diagonal coupling terms, without free-space assumptions or antenna models.
  • Remote single-port load-impedance sensing no longer requires a perfectly matched or perfectly known antenna; three distinct known terminations are sufficient in a general environment.
  • Because the wireless environment is treated as a fixture to be characterized, the same procedure should work in any linear, passive, reciprocal propagation environment, including non-reverberant indoor spaces.
  • For DUTs with known zero inter-port transmission, coupled-load terminations are unnecessary, which simplifies the hardware requirement.
  • When multiple DUT ports exist, only two distinct individual loads are needed per port as long as coupled-load terminations are available, relaxing the Virtual VNA's hardware needs.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

  • A natural but untested extension is to move the same three-step procedure into an ordinary indoor environment; the recovered DUT should match the direct VNA ground truth regardless of wall reflections, since the method is explicitly environment-agnostic.
  • The sign-ambiguity cancellation relies on the symmetric appearance of $S^F_{AS}$ and $S^F_{SA}$ in the de-embedding equation; for non-reciprocal fixtures this cancellation may fail, so the extension to non-reciprocal wireless channels would need the non-reciprocal Virtual VNA variants.
  • Because wireless power harvesting can run the switches, the simplified load-network requirements found here bring a fully untethered, battery-free multi-port sensing tag closer to practical realization.
  • The paper's restriction to non-radiating DUTs suggests a clean boundary: radiating DUTs should be treated as remote reflection-matrix sensing rather than load-matrix sensing, and the same Virtual VNA machinery already covers that case.
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Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, and a circularity audit.

Referee Report

3 major / 6 minor

Summary. The paper proposes a three-step method for over-the-air (OTA) estimation of the scattering matrix of a linear, passive, time-invariant, reciprocal multi-port DUT. The DUT is connected to 'not-directly-accessible' (NDA) antennas that couple through an arbitrary WPE to 'accessible' antennas attached to a VNA. Step 1 characterizes the OTA fixture SF by terminating the NDA antennas with a known tunable load network and applying a gradient-descent Virtual VNA inversion to measured S or H. Step 2 measures the accessible-port scattering with the DUT attached. Step 3 de-embeds SF by minimizing the cost in Eq. (3)/(4), with reciprocity as the only constraint on the unknown SD, to recover the DUT scattering matrix. The method is validated at 2.45 GHz in a reverberation chamber for a 1-port DUT and a 5-port DUT, with MSE values near 1e-5, and benchmarked against simplified load networks and a simplified system model. The paper claims this is the first method to unambiguously recover a full multi-port load-impedance matrix OTA with no assumptions on the WPE beyond linearity, passivity, time-invariance, and reciprocity.

Significance. If the central claim is supported, this is a useful and timely contribution: it extends the Virtual VNA idea from cabled/array measurements to truly wireless sensing of a non-radiating DUT, and it provides the first OTA estimate of a full load-impedance matrix in a rich-scattering environment. The experimental work is a real strength: cabled ground-truth comparison, systematic sweeps of accessible-antenna number and measurement count (Tables I and III), and careful benchmarking of hardware simplifications (A1-A3, B) that reveals where the method breaks. The network-theoretic foundation, Eq. (1), is standard, and the sign-ambiguity cancellation argument is credible. However, the 'unambiguous' claim is not yet fully established: no identifiability or convergence analysis is supplied for the two gradient-descent inversions, and the H/NA=8 failure (Sec. IV-C) shows that parameter counting alone does not ensure a well-posed inverse problem. The explicit scope restriction to DUTs that couple to the WPE only through lumped monomodal ports is honestly stated and excludes radiating DUTs such as antenna arrays.

major comments (3)
  1. [Sec. III-B, Eqs. (1)-(4), Tables II-III] The central claim of unambiguous recovery requires a proof that the two gradient-descent inversions are identifiable and that the algorithm converges to the desired solution (up to the tolerated sign ambiguity). The paper offers only a parameter count (Table II), which is necessary but not sufficient; the H/NA=8 case in Sec. IV-C is concrete evidence that exceeding the parameter count does not guarantee a well-posed inversion (16 independent complex measurements versus 15 complex unknowns, yet the estimate fails with an MSE four orders of magnitude above the S/NA=8 case). Please supply an identifiability/conditioning analysis of the mappings in Eqs. (1)-(4), or at minimum demonstrate through multiple random restarts and initialization sweeps for Steps 1 and 3 that the reported minima are the intended global minima.
  2. [Sec. III-B1] The 'sufficiently unambiguous' characterization of SF relies on two assertions: (i) with the available load configurations, the only remaining ambiguity is the common sign of S_AS and S_SA, and (ii) this sign ambiguity cancels in Eq. (1). Assertion (ii) is correct by inspection, but assertion (i) is imported from the author's prior Virtual VNA papers [17], [22], [23] and is not derived or verified in the present manuscript. Because any unmodeled ambiguity from Step 1 propagates into the Step 3 estimate of SD, the paper should prove this identifiability statement or explicitly restate the relevant theorem from [22] in this paper's notation.
  3. [Sec. IV-A and Sec. V] The experimental validation uses one WPE (a single reverberation chamber at 2.45 GHz), one antenna layout, and two DUTs, while the Introduction and Conclusion claim a general method with no WPE-specific assumptions. A single rich-scattering configuration cannot by itself validate a universal claim, especially because the robustness is shown to depend on the conditioning of the inverse problem (Tables I-III). Either temper the wording to 'proof-of-concept' in the Conclusion, or add a second environment (e.g., free-space/anechoic or an indoor propagation environment) or a controlled variation of NDA-antenna coupling to support the generality.
minor comments (6)
  1. [Abstract / Introduction] The Abstract and Introduction use 'unambiguously' without the qualification introduced later in Sec. III-B1 that one operationally irrelevant sign ambiguity on the off-diagonal blocks of SF remains; this should be stated in the abstract for accuracy.
  2. [Sec. II, last paragraph] The key restriction that the DUT must not radiatively couple to the WPE is introduced only at the end of Sec. II and in footnote 3; stating it at the beginning of Sec. II and in the abstract would prevent overbroad reading of the phrase 'without any assumptions about the antennas'.
  3. [Sec. IV-A] The gradient-descent hyperparameters (initialization, learning rate, stopping criterion) for Steps 1 and 3 are not reported; without them the experimental results cannot be reproduced by others.
  4. [Table I] The MSE for NA=6 (1.40e-5 for S) is lower than for NA=8 (1.99e-5); this non-monotonicity is not commented on and deserves a sentence of explanation.
  5. [Sec. III-B1 / Sec. IV-C] The claim that two individual loads plus 2PLNs provide at least three distinct terminations for NS>1 is central to benchmark A2's success; a short explicit construction would make this easier to verify than the current verbal statement.
  6. [Sec. IV-C] The sentence reporting the failure of H with NA=8 does not indicate whether the failure is attributed to ill-conditioning, noise sensitivity, or local minima; an explicit diagnosis would strengthen the discussion of Table II.

Circularity Check

0 steps flagged · score 0.0 of 10

No circularity: Step 1 builds on the separately published Virtual VNA technique as a dependency, and Step 3 is an independent inversion validated against cabled ground truth; the cited identifiability gap is a soundness concern, not a loop.

full rationale

The paper's central claim—unambiguous over-the-air recovery of a multi-port DUT's scattering matrix—does not reduce by construction to its inputs. Step 1 estimates the fixed OTA-fixture matrix SF from measured scattering with known load terminations, relying on the author's prior Virtual VNA work ([17], [22], [23]). This is a citation of separate, experimentally validated prior results with stated assumptions (linear, passive, time-invariant, reciprocal networks), not a definitional loop: the prior work does not assume the target result of the present paper, and the present paper's de-embedding is independently tested against cabled ground truth. Step 3 inverts the standard multi-port network formula (1)/(2) for the unknown SL=SD given the estimated SF; the cost function (3)/(4) compares predictions with the measured accessible-port scattering, and the DUT ground truth is used only for evaluation, never as a fitted input. No fitted parameter is renamed as a prediction, and no component of SD is reused to produce the claim. The tolerated sign ambiguity on SF_AS=(SF_SA)^T is explicitly shown to cancel in (1), so it is not smuggled in. The paper's self-citations are load-bearing in the sense of building on prior published work, but that is a normal dependency, not circularity; the prior Virtual VNA results are externally falsifiable and do not incorporate the present paper's fitted values. The principal substantive weakness—the lack of an identifiability and convergence proof for the two gradient-descent inversions, made concrete by the H/NA=8 failure despite parameter counting in Table II—is a soundness or robustness concern, not a circularity. Accordingly, no circular step is present and the score is 0.

Assumptions & free parameters 1 free parameters · 6 assumptions · 0 invented entities

The method adds a new estimation procedure, not new physical entities. The main load-bearing inputs are standard network theory and a set of domain assumptions about the DUT, the fixture, and the load network. The only hand-chosen numerical elements are undisclosed gradient-descent settings, which affect reproducibility rather than the physical model. The self-cited Virtual VNA foundation is treated as established from [17], [22], [23] rather than re-derived here.

free parameters (1)
  • Gradient-descent hyperparameters (initialization, learning rate, stopping criterion) for Step 1 and Step 3 = not disclosed
    The de-embedding and fixture characterization outcomes depend on these choices; the paper reports no sensitivity analysis or code, so the central results are not reproducible from the text alone.
assumptions (6)
  • standard math Scattering relation S = S_F_AA + S_F_AS (S_L^-1 - S_F_SS)^-1 S_F_SA from multi-port network theory
    Used without proof in Sec. II, citing [39], [40].
  • domain assumption DUT and WPE are linear, passive, time-invariant; WPE is reciprocal; ports are lumped and monomodal
    Stated at the start of Sec. II and in the Introduction as the operating scope.
  • domain assumption DUT interacts with the WPE only through its NS lumped monomodal ports, with no radiation-mode coupling
    Explicitly stated in the final paragraph of Sec. II; the method breaks for radiating DUTs such as antenna arrays.
  • domain assumption Tunable load network is known and satisfies the Virtual VNA requirements: three distinct known individual loads and known 2PLNs
    Required in Sec. II and used throughout Step 1; the experimental implementation measures these characteristics at 2.45 GHz.
  • domain assumption The OTA fixture is unchanged between Step 1 and Step 2
    Stability is reported as 59.1 dB in Sec. IV-A, but the algorithm has no built-in robustness to fixture drift.
  • ad hoc to paper Gradient descent in Steps 1 and 3 converges to the desired global optimum
    No uniqueness or convergence proof is given; the method relies on empirical success in the tested configurations.

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Cite this review

Pith. "Pith review of Wireless Multi-Port Sensing: Virtual-VNA-Enabled De-Embedding of an Over-the-Air Fixture." pith.science (2026). https://pith.science/paper/HFS3Z7LV

@misc{pith2026250712909,
  author       = {Pith},
  title        = {Pith review of: Wireless Multi-Port Sensing: Virtual-VNA-Enabled De-Embedding of an Over-the-Air Fixture},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/HFS3Z7LV}},
  note         = {Machine review of arXiv:2507.12909}
}
read the original abstract

We develop a multi-port-backscatter-modulation technique to determine, over the air (OTA), the scattering parameters of a linear, passive, time-invariant multi-port device under test (DUT). A set of "not-directly-accessible" (NDA) antennas can be switched between being terminated by the DUT or by a specific, known, tunable load network. Waves can be radiated and captured via a distinct set of "accessible" antennas that couple OTA to the NDA antennas. First, we characterize the OTA fixture between the accessible antennas' ports and the DUT's ports. We achieve this based on our recently introduced "Virtual VNA" technique; specifically, we connect the NDA antennas to the tunable load network and measure the scattering at the accessible antennas' ports for various configurations of the tunable load network. Second, we connect the NDA antennas to the DUT and measure the scattering at the accessible antennas' ports. Third, we de-embed the OTA fixture to retrieve the DUT's scattering parameters. We experimentally validate our technique at 2.45 GHz for 1-port DUTs and 5-port DUTs, considering a rich-scattering OTA fixture inside a reverberation chamber. We systematically study the influence of the number of accessible antennas and various conceivable simplifications in terms of the system model as well as the properties of the tunable load network. Our wireless multi-port sensing technique can find applications in areas like RFID and wireless bioelectronics.

Figures

Figures reproduced from arXiv: 2507.12909 by the authors.

Figure 1
Figure 1. (a) Principle of wireless multi-port sensing with an OTA fixture. [PITH_FULL_IMAGE:figures/full_fig_p003_1.png] view at source ↗
Figure 2
Figure 2. Schematic drawing and photographic images of the experimental setup (top cover removed to show interior). The scattering parameters of the tunable [PITH_FULL_IMAGE:figures/full_fig_p006_2.png] view at source ↗
Figure 3
Figure 3. Selected experimental results for remote load-impedance sensing ( ( [PITH_FULL_IMAGE:figures/full_fig_p007_3.png] view at source ↗
Figures from the paper (1 more)
Figure 4
Figure 4. Figure 4: Selected experimental results for remote load-impedance-matrix sensing ( [PITH_FULL_IMAGE:figures/full_fig_p008_4.png]

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Reference graph

Works this paper leans on

48 extracted references · 42 canonical work pages · cited by 1 Pith paper

  1. [17]

    Virtual VNA: Minimal-ambiguity scattering matrix estimation with a fixed set of “virtual

    P. del Hougne, “Virtual VNA: Minimal-ambiguity scattering matrix estimation with a fixed set of “virtual” load-tunable ports,” IEEE Trans. Instrum. Meas., vol. 74, pp. 1–19, 2025

    2025

  2. [22]

    Virtual VNA 2.0: Ambiguity-free scattering matrix estimation by terminating not-directly-accessible ports with tunable and coupled loads,

    P. del Hougne, “Virtual VNA 2.0: Ambiguity-free scattering matrix estimation by terminating not-directly-accessible ports with tunable and coupled loads,” IEEE Trans. Antennas Propag., vol. 73, no. 7, pp. 4903– 4908, 2025

    2025

  3. [23]

    Scalable multiport antenna array characterization with PCB-realized tunable load network providing additional “virtual

    J. Tapie and P. del Hougne, “Scalable multiport antenna array characterization with PCB-realized tunable load network providing additional “virtual” VNA ports,” IEEE Antennas Wirel. Propag. Lett. , 2025

    2025

  4. [1]

    Lev Termen’s Great Seal bug analyzed,

    G. Brooker and J. Gomez, “Lev Termen’s Great Seal bug analyzed,” IEEE Aerosp. Electron. Syst. Mag. , vol. 28, no. 11, pp. 4–11, 2013

    work page 2013

  5. [2]

    Pervasive electromagnetics: sensing paradigms by passive RFID technology,

    G. Marrocco, “Pervasive electromagnetics: sensing paradigms by passive RFID technology,” IEEE Wirel. Commun. , vol. 17, no. 6, pp. 10–17, 2010

    work page 2010

  6. [3]

    RFID grids: Part I—Electromagnetic theory,

    G. Marrocco, “RFID grids: Part I—Electromagnetic theory,” IEEE Trans. Antennas Propag., vol. 59, no. 3, pp. 1019–1026, 2011

    work page 2011

  7. [4]

    RFID grids: Part II—Experimentations,

    S. Caizzone and G. Marrocco, “RFID grids: Part II—Experimentations,” IEEE Trans. Antennas Propag. , vol. 59, no. 8, pp. 2896–2904, 2011

    work page 2011

  8. [5]

    Multiport sensor RFIDs for wireless passive sensing of objects—Basic theory and early results,

    G. Marrocco et al., “Multiport sensor RFIDs for wireless passive sensing of objects—Basic theory and early results,” IEEE Trans. Antennas Propag., vol. 56, no. 8, pp. 2691–2702, 2008

    work page 2008

Show all 48 references
  1. [6]

    Statistical evaluation of the coupling effects between tags in a UHF RFID forward link,

    A. Mughal et al., “Statistical evaluation of the coupling effects between tags in a UHF RFID forward link,” IEEE J. Radio Freq. Identif., vol. 7, pp. 257–266, 2023. 10

    2023

  2. [7]

    Experimental evaluation and upper- bounds of cross-sensitivity in stacked RFID sensors,

    F. M. C. Nanni and G. Marrocco, “Experimental evaluation and upper- bounds of cross-sensitivity in stacked RFID sensors,” IEEE J. Radio Freq. Identif., vol. 8, pp. 98–104, 2024

    2024

  3. [8]

    Differential RCS of multi-port tag antenna with synchronous modulated backscatter,

    N. Barbot et al. , “Differential RCS of multi-port tag antenna with synchronous modulated backscatter,” IEEE J. Radio Freq. Identif., 2025

    2025

  4. [9]

    Multi-chip RFID antenna integrating shape-memory alloys for detection of thermal thresholds,

    S. Caizzone et al., “Multi-chip RFID antenna integrating shape-memory alloys for detection of thermal thresholds,” IEEE Trans. Antennas Propag., vol. 59, no. 7, pp. 2488–2494, 2011

    2011

  5. [10]

    Determination of antenna parameters by scattering cross- section measurements,

    R. Garbacz, “Determination of antenna parameters by scattering cross- section measurements,” Proc. Inst. Electr. Eng. , vol. 111, no. 10, pp. 1679–1686, 1964

    1964

  6. [11]

    A technique for measuring antenna drive port impedance using backscatter data,

    J. T. Mayhan et al. , “A technique for measuring antenna drive port impedance using backscatter data,” IEEE Trans. Antennas Propag. , vol. 42, no. 4, pp. 526–533, 1994

    1994

  7. [12]

    Backscattering-based measurement of reactive antenna input impedance,

    P. Pursula et al., “Backscattering-based measurement of reactive antenna input impedance,” IEEE Trans. Antennas Propag. , vol. 56, no. 2, pp. 469–474, 2008

    2008

  8. [13]

    Small antennas impedance and gain characterization using backscattering measurements,

    S. Bories et al. , “Small antennas impedance and gain characterization using backscattering measurements,” Proc. EuCAP, 2010

    2010

  9. [14]

    Verification of a contactless characterization method for millimeter-wave integrated antennas,

    A. J. Van Den Biggelaar et al. , “Verification of a contactless characterization method for millimeter-wave integrated antennas,” IEEE Trans. Antennas Propag., vol. 68, no. 5, pp. 3358–3365, 2020

    2020

  10. [15]

    Noncontact characterization of antenna parameters in mmW and THz bands,

    S. Sahin et al. , “Noncontact characterization of antenna parameters in mmW and THz bands,” IEEE Trans. Terahertz Sci. Technol. , vol. 12, no. 1, pp. 42–52, 2021

    2021

  11. [16]

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

    D. Kruglov et al. , “Contactless measurement of a D-band on-chip antenna using an integrated reflective load switch,”IEEE Antennas Wirel. Propag. Lett., vol. 23, no. 3, pp. 1075–1079, 2023

    2023

  12. [18]

    Wide-band multiport antenna characterization by polarimetric RCS measurements,

    W. Wiesbeck and E. Heidrich, “Wide-band multiport antenna characterization by polarimetric RCS measurements,” IEEE Trans. Antennas Propag., vol. 46, no. 3, pp. 341–350, 1998

    1998

  13. [19]

    Multiport small integrated antenna impedance matrix measurement by backscattering modulation,

    B. Monsalve et al. , “Multiport small integrated antenna impedance matrix measurement by backscattering modulation,” IEEE Trans. Antennas Propag., vol. 61, no. 4, pp. 2034–2042, 2013

    2013

  14. [20]

    Antenna array measurements by a scalable backscatter modulation procedure,

    I. Shilinkov and R. Maaskant, “Antenna array measurements by a scalable backscatter modulation procedure,” IEEE Antennas Wirel. Propag. Lett., vol. 23, no. 10, pp. 2989–2993, 2024

    2024

  15. [21]

    The application of multiport theory for MIMO RFID backscatter channel measurements,

    E. Denicke et al., “The application of multiport theory for MIMO RFID backscatter channel measurements,” Proc. EuMC, pp. 522–525, 2012

    2012

  16. [24]

    De-embedding and unterminating,

    R. F. Bauer and P. Penfield, “De-embedding and unterminating,” IEEE Trans. Microw. Theory Techn., vol. 22, no. 3, pp. 282–288, 1974

    1974

  17. [25]

    Reconstruction of the S-matrix for a 3-port using measurements at only two ports,

    M. Davidovitz, “Reconstruction of the S-matrix for a 3-port using measurements at only two ports,” IEEE Microw. Guid. Wave Lett., vol. 5, no. 10, pp. 349–350, 1995

    1995

  18. [26]

    Port reduction methods for scattering matrix measurement of an n-port network,

    H.-C. Lu and T.-H. Chu, “Port reduction methods for scattering matrix measurement of an n-port network,” IEEE Trans. Microw. Theory Techn., vol. 48, no. 6, pp. 959–968, 2000

    2000

  19. [27]

    Multiport scattering matrix measurement using a reduced-port network analyzer,

    H.-C. Lu and T.-H. Chu, “Multiport scattering matrix measurement using a reduced-port network analyzer,” IEEE Trans. Microw. Theory Techn., vol. 51, no. 5, pp. 1525–1533, 2003

    2003

  20. [28]

    A recursive un-termination method for nondestructive in situ S-parameter measurement of hermetically encapsulated packages,

    U. R. Pfeiffer and C. Schuster, “A recursive un-termination method for nondestructive in situ S-parameter measurement of hermetically encapsulated packages,” IEEE Trans. Microw. Theory Techn. , vol. 53, no. 6, pp. 1845–1855, 2005

    2005

  21. [29]

    Equivalent circuit model extraction of flip-chip ball interconnects based on direct probing techniques,

    U. Pfeiffer and B. Welch, “Equivalent circuit model extraction of flip-chip ball interconnects based on direct probing techniques,” IEEE Microw. Wirel. Compon. Lett., vol. 15, no. 9, pp. 594–596, 2005

    2005

  22. [30]

    Characterization of flip- chip interconnects up to millimeter-wave frequencies based on a nondestructive in situ approach,

    U. R. Pfeiffer and A. Chandrasekhar, “Characterization of flip- chip interconnects up to millimeter-wave frequencies based on a nondestructive in situ approach,” IEEE Trans. Adv. Packag. , vol. 28, no. 2, pp. 160–167, 2005

    2005

  23. [31]

    Virtual VNA 3.0: Unambiguous scattering matrix estimation for non-reciprocal systems by leveraging tunable and coupled loads,

    P. del Hougne, “Virtual VNA 3.0: Unambiguous scattering matrix estimation for non-reciprocal systems by leveraging tunable and coupled loads,” arXiv:2503.07239, 2025

    2025 arXiv

  24. [32]

    Virtual VNA 3.1: Non-coherent-detection-based non- reciprocal scattering matrix estimation leveraging a tunable load network,

    P. del Hougne, “Virtual VNA 3.1: Non-coherent-detection-based non- reciprocal scattering matrix estimation leveraging a tunable load network,” arXiv:2504.11790, 2025

    2025 arXiv

  25. [33]

    Wireless impedance measurement of UHF RFID tag chips,

    H.-Y . Chen et al., “Wireless impedance measurement of UHF RFID tag chips,” Proc. IMS, pp. 1–3, 2012

    2012

  26. [34]

    Wireless measurement of RFID IC impedance,

    T. Bjorninen et al. , “Wireless measurement of RFID IC impedance,” IEEE Trans. Instrum. Meas. , vol. 60, no. 9, pp. 3194–3206, 2011

    2011

  27. [35]

    RFID tag load impedance measurement using backscattered signal,

    M. Akbar et al. , “RFID tag load impedance measurement using backscattered signal,” IEEE Int. Symp. Antennas Propag. USNC/URSI Natl. Radio Sci. Meet. , pp. 1762–1763, 2015

    2015

  28. [36]

    A new concept of determining the RFID chip impedance,

    K. Skrobacz et al. , “A new concept of determining the RFID chip impedance,” IEEE Trans. Microw. Theory Tech., 2024

    2024

  29. [37]

    Coupling passive sensors to UHF RFID tags,

    H.-Y . Chen et al., “Coupling passive sensors to UHF RFID tags,” Proc. IEEE Radio Wirel. Symp. , pp. 255–258, 2012

    2012

  30. [38]

    Backscatter-based wireless sensing system for multi- channel complex impedance measurements,

    A. Vena et al. , “Backscatter-based wireless sensing system for multi- channel complex impedance measurements,” Proc. Int. Conf. Smart Sustain. Tech., pp. 1–4, 2024

    2024

  31. [39]

    Cascade connection for time- invariant n-port networks,

    B. D. O. Anderson and R. W. Newcomb, “Cascade connection for time- invariant n-port networks,” Proc. Inst. Electr. Eng. , vol. 113, no. 6, pp. 970–974, Jun. 1966

    1966

  32. [40]

    T. T. Ha, Solid-State Microwave Amplifier Design . Wiley-Interscience, 1981

    1981

  33. [41]

    Optimal blind focusing on perturbation-inducing targets in sub-unitary complex media,

    J. Sol et al., “Optimal blind focusing on perturbation-inducing targets in sub-unitary complex media,” Laser Photonics Rev., p. 2400619, 2024

    2024

  34. [42]

    Relationships between antennas as scatterers and as radiators,

    R. C. Hansen, “Relationships between antennas as scatterers and as radiators,” Proc. IEEE, vol. 77, no. 5, pp. 659–662, 1989

    1989

  35. [43]

    Beyond-diagonal RIS prototype and performance evaluation,

    J. Tapie et al. , “Beyond-diagonal RIS prototype and performance evaluation,” arXiv:2505.13392, 2025

    2025 arXiv

  36. [44]

    Experimental multiport-network parameter estimation and optimization for multi-bit RIS,

    P. del Hougne, “Experimental multiport-network parameter estimation and optimization for multi-bit RIS,” arXiv:2507.02168, 2025

    2025 arXiv

  37. [45]

    A physics-compliant diagonal representation for wireless channels parametrized by beyond-diagonal reconfigurable intelligent surfaces,

    P. del Hougne, “A physics-compliant diagonal representation for wireless channels parametrized by beyond-diagonal reconfigurable intelligent surfaces,” IEEE Trans. Wirel. Commun. , 2025

    2025

  38. [46]

    Deeply subwavelength localization with reverberation-coded aperture,

    M. del Hougne et al. , “Deeply subwavelength localization with reverberation-coded aperture,” Phys. Rev. Lett., vol. 127, p. 043903, Jul 2021

    2021

  39. [47]

    Mutual coupling in dynamic metasurface antennas: Foe, but also friend,

    H. Prod’homme and P. del Hougne, “Mutual coupling in dynamic metasurface antennas: Foe, but also friend,” arXiv:2412.01002, 2024

    2024 arXiv

  40. [48]

    Benefits of mutual coupling in dynamic metasurface antennas for optimizing wireless communications - theory and experimental validation,

    H. Prod’homme et al. , “Benefits of mutual coupling in dynamic metasurface antennas for optimizing wireless communications - theory and experimental validation,” arXiv:2502.15565, 2025

    2025

Pith tools

Reviewed August 6, 2026 · model on record in the stance chip above.