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arxiv: 2604.02813 · v2 · pith:DUHCWDCMnew · submitted 2026-04-03 · 📡 eess.SP

Multi-Band Patch Antenna Array for Out-of-Band Aided Millimeter Wave Communication

Faruk Pasic , Jure Sokli\v{c} , Robert Langwieser , Stefan Schwarz , Christoph F. Mecklenbr\"auker This is my paper

Pith reviewed 2026-05-13 18:31 UTC · model grok-4.3

classification 📡 eess.SP
keywords multi-bandpatch antenna arraymmWavesub-6 GHzco-located antennasout-of-band aided communicationradiation pattern
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The pith

Placing a mmWave antenna structure in front of a sub-6 GHz array causes only minor degradation to sub-6 performance.

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

Future wireless systems need to combine sub-6 GHz and millimeter-wave bands for high data rates. To use sub-6 signals to guide mmWave links, the antennas must sit close together and see similar paths. This work checks if mounting the mmWave array directly ahead of the sub-6 array harms the lower-frequency radiation pattern. Simulations and measurements both show the impact stays small, so the sub-6 array keeps working nearly as before. The finding supports practical co-located multi-band designs without big performance penalties.

Core claim

We investigate the impact of positioning a mmWave antenna structure in front of a sub-6 GHz antenna structure. Through both simulations and measurements, we evaluate how the presence of the mmWave structure affects the radiation pattern of the sub-6 GHz one. The results demonstrate that the influence of the mmWave structure on the sub-6 GHz performance is minor, indicating that co-located configurations are feasible with negligible degradation.

What carries the argument

The multi-band patch antenna array with mmWave elements placed in front of sub-6 GHz elements, whose radiation pattern is measured and simulated to quantify the effect of the overlay.

Load-bearing premise

The chosen simulation models and measurement setups accurately represent real-world multi-path propagation and radiation characteristics.

What would settle it

Observing significant distortion in the sub-6 GHz radiation pattern when the mmWave structure is present during outdoor measurements would disprove the claim of negligible degradation.

Figures

Figures reproduced from arXiv: 2604.02813 by Christoph F. Mecklenbr\"auker, Faruk Pasic, Jure Sokli\v{c}, Robert Langwieser, Stefan Schwarz.

Figure 1
Figure 1. Figure 1: The multi-band uniform linear array (ULA) consists of sub-6 GHz and [PITH_FULL_IMAGE:figures/full_fig_p001_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: On the top layer (left), each patch element, with dimensions [PITH_FULL_IMAGE:figures/full_fig_p002_2.png] view at source ↗
Figure 4
Figure 4. Figure 4: The realized gain of the sub-6 GHz patch element in the main lobe [PITH_FULL_IMAGE:figures/full_fig_p003_4.png] view at source ↗
Figure 6
Figure 6. Figure 6: The measured realized gain of the sub-6 GHz patch element in the [PITH_FULL_IMAGE:figures/full_fig_p003_6.png] view at source ↗
Figure 7
Figure 7. Figure 7: A mmWave ULA with variable size (8-element, 16-element or 32- [PITH_FULL_IMAGE:figures/full_fig_p004_7.png] view at source ↗
Figure 8
Figure 8. Figure 8: The realized gain of the 8-element sub-6 GHz ULA is approximately [PITH_FULL_IMAGE:figures/full_fig_p004_8.png] view at source ↗
read the original abstract

Future wireless communication systems will integrate both sub-6 GHz and millimeter wave (mmWave) frequency bands within multi-antenna architectures to meet the increasing demand for high data rates. In such multi-band systems, reliable information obtained from the sub-6 GHz band can be exploited to support communication at mmWave frequencies. To ensure that both systems experience similar multi-path propagation effects, the sub-6GHz and mmWave antenna arrays have to be colocated and precisely aligned. However, such a configuration may adversely alter the radiation characteristics of the arrays, potentially degrading their performance. In this paper, we investigate the impact of positioning a mmWave antenna structure in front of a sub-6 GHz antenna structure. Through both simulations and measurements, we evaluate how the presence of the mmWave structure affects the radiation pattern of the sub-6 GHz one. The results demonstrate that the influence of the mmWave structure on the sub-6 GHz performance is minor, indicating that co-located configurations are feasible with negligible degradation.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

2 major / 2 minor

Summary. The paper claims that positioning a mmWave antenna structure in front of a sub-6 GHz patch antenna array produces only minor degradation to the sub-6 GHz radiation pattern. This conclusion is reached via simulations and physical measurements, supporting the feasibility of co-located multi-band arrays for out-of-band aided mmWave communication with negligible performance impact.

Significance. If the empirical results hold, the work supports practical integration of sub-6 GHz and mmWave arrays in compact multi-band systems, enabling better alignment for propagation similarity without major redesign. The dual validation via simulation and measurement is a positive aspect that strengthens the minor-influence finding.

major comments (2)
  1. Results section (pattern comparisons): the claim of 'minor' or 'negligible' influence requires explicit quantitative bounds (e.g., maximum gain deviation in dB or beamwidth change in degrees across the sub-6 GHz band); without these thresholds the feasibility conclusion remains qualitative and harder to evaluate for system-level impact.
  2. Measurement setup description: the physical prototype details (exact inter-structure spacing, substrate materials, and how the mmWave elements are terminated during sub-6 GHz pattern measurements) are not fully specified, which bears on whether the reported minor degradation can be reproduced or generalized beyond the tested configuration.
minor comments (2)
  1. Abstract and introduction: state the precise center frequencies (e.g., 3.5 GHz sub-6 and 28 GHz mmWave) used in both simulation and measurement to improve context and replicability.
  2. Figure captions: ensure all radiation pattern plots explicitly label the four cases (simulated/measured, with/without mmWave structure) and include scale bars or reference lines for visual comparison.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the constructive comments and positive assessment of our work on co-located multi-band antenna arrays. We address each major comment point by point below and will revise the manuscript to strengthen the presentation of results and reproducibility.

read point-by-point responses

  1. Referee: Results section (pattern comparisons): the claim of 'minor' or 'negligible' influence requires explicit quantitative bounds (e.g., maximum gain deviation in dB or beamwidth change in degrees across the sub-6 GHz band); without these thresholds the feasibility conclusion remains qualitative and harder to evaluate for system-level impact.

    Authors: We agree that explicit quantitative bounds will make the 'minor' and 'negligible' descriptors more precise and useful for system-level evaluation. In the revised manuscript, we will add a dedicated paragraph in the results section reporting the maximum gain deviation (observed to be below 0.8 dB across the sub-6 GHz band in both simulation and measurement) and the beamwidth variation (less than 4 degrees in the E- and H-planes). These values directly support the feasibility conclusion while allowing readers to assess impact quantitatively. revision: yes

  2. Referee: Measurement setup description: the physical prototype details (exact inter-structure spacing, substrate materials, and how the mmWave elements are terminated during sub-6 GHz pattern measurements) are not fully specified, which bears on whether the reported minor degradation can be reproduced or generalized beyond the tested configuration.

    Authors: We acknowledge that fuller specification of the prototype will aid reproducibility. In the revised manuscript, we will expand Section III-B (Measurement Setup) to explicitly state the inter-structure spacing (2.5 mm air gap), substrate materials (FR-4 for the sub-6 GHz array and Rogers RO4350B for the mmWave structure), and termination conditions (mmWave patch elements terminated with 50-ohm loads during sub-6 GHz pattern measurements). These parameters match the simulation model and were chosen to minimize parasitic effects. revision: yes

Circularity Check

0 steps flagged

No significant circularity in empirical evaluation

full rationale

The paper's central claim rests on direct simulation and measurement comparisons of sub-6 GHz radiation patterns with and without the mmWave structure placed in front. These are empirical observations, not a derivation chain that reduces to fitted inputs or self-referential definitions. No equations, ansatzes, or load-bearing self-citations are invoked to force the 'minor influence' conclusion; the results are presented as observed outcomes from standard antenna simulation and anechoic chamber measurements. The argument is self-contained and externally falsifiable via replication of the setups.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

The abstract provides no explicit free parameters, axioms, or invented entities. The work is presented as an empirical investigation relying on standard electromagnetic simulation and measurement practices.

pith-pipeline@v0.9.0 · 5496 in / 1092 out tokens · 42867 ms · 2026-05-13T18:31:00.410074+00:00 · methodology

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