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PhysBound

Physical Layer Linter — an MCP server that validates RF and physics calculations against hard physical limits, catching AI hallucinations in engineering workflows.

LLMs generate plausible-sounding RF numbers that violate fundamental physics — throughput above the Shannon limit, antenna gains no aperture can produce, radar ranges the range equation forbids. PhysBound gives any MCP-compatible AI assistant six validated calculation tools, backed by CODATA constants (via SciPy) and dimensional analysis (via Pint). Impossible claims return structured PhysicalViolationError responses with the violated law, the computed limit, and a LaTeX explanation — not silent failures.

The Six Tools

Tool What it validates
rf_link_budget Friis link budgets: FSPL, received power, antenna gains vs. aperture/Harrington limits
shannon_hartley Throughput claims against channel capacity \(C = B \log_2(1 + \mathrm{SNR})\)
noise_floor Thermal noise \(kTB\), Friis noise-figure cascades, receiver sensitivity
radar_range Detection-range claims against the monostatic radar range equation
antenna_gain Gain limits, beamwidth, and far-field distance for a single antenna
radar_ambiguity Pulse-Doppler unambiguous range/velocity, Doppler aliasing, range resolution

Every formula, constant, and validation guard is documented with sources in the Formula Reference.

How It Works

Ask your MCP-connected assistant an RF question — "Can a 20 MHz channel with 15 dB SNR support 500 Mbps?" — and it calls PhysBound instead of guessing. The answer comes back physics-validated:

  • Possible claims return the full calculation: capacity, spectral efficiency, margins, and any applicability warnings.
  • Impossible claims return a structured PhysicalViolationError naming the violated law (here, the Shannon–Hartley theorem: the 20 MHz / 15 dB channel caps out at 100.6 Mbps), the computed limit, the claimed value, and a LaTeX explanation of why.

Physics Guarantees

Every calculation is checked against hard physical limits:

  • Speed of light: \(c = 299{,}792{,}458\ \mathrm{m/s}\) — no exceptions
  • Thermal noise floor: \(-174\ \mathrm{dBm/Hz}\) at 290 K — the IEEE standard reference
  • Shannon limit: \(C = B \log_2(1 + \mathrm{SNR})\) — no throughput claim exceeds this
  • Antenna gain limit: \(G_{\max} = \max\!\left[(\pi D/\lambda)^2,\ (ka)^2 + 2ka\right]\) — the \(\eta = 1\) aperture value, or Harrington's bound for electrically small antennas
  • Radar range equation: range obeys the fourth-root law — doubling power multiplies range by \(2^{1/4} \approx 1.19\), not 2
  • Range–Doppler dilemma: \(R_{ua} \cdot v_{ua} = c\lambda/8\) — no PRF choice beats it for a given carrier

Getting Started

  • Installation — connect PhysBound to Claude Code, Claude Desktop, Cursor, Windsurf, or any MCP client
  • CLI — validate claims from the terminal or CI with physbound check
  • Formula Reference — every formula with derivations and sources

PhysBound is MIT licensed and developed on GitHub. Contributions that expand the set of validated physics domains are welcome — see the contributing guide.