| AR |
Axial Ratio — ratio of semi-major to semi-minor axis of the polarization ellipse, expressed in dB. 0 dB = perfect circular; ∞ dB = perfect linear. |
| CST |
Computer Simulation Technology — vendor for EM simulation; their .ffs Farfield Source format is supported as an RFlect export target. |
| Directivity |
Peak gain divided by spherical-average gain. The "shape" of the pattern, independent of efficiency. |
| ECC |
Envelope Correlation Coefficient — how correlated two antenna patterns are; matters for MIMO diversity. |
| Efficiency (η) |
Radiated power / accepted power. Includes ohmic and mismatch losses. |
| F/B |
Front-to-Back ratio. Gain at the peak direction minus gain at 180° from the peak. |
| Gain |
Power radiated in a given direction per unit solid angle, relative to isotropic. Gain = Efficiency × Directivity. dBi units. |
| HPBW |
Half-Power Beamwidth, aka -3 dB beamwidth. Angular width where gain drops to half-peak. |
| HPOL / VPOL |
H- and V-polarization. Ludwig-3: HPOL → $E_\phi$, VPOL → $E_\theta$. |
| Kraus |
Approximation for efficiency: $\eta \approx 32400 / (\text{HPBW}_E \cdot \text{HPBW}_H)$. Only valid for moderately directional antennas. |
| LHCP / RHCP |
Left-/Right-Hand Circular Polarization. IEEE convention: looking in direction of propagation. |
| MCP |
Model Context Protocol — open spec for AI assistants to call tools on external servers. |
| MEG |
Mean Effective Gain — mean of the antenna gain weighted by the angular power spectrum of the environment. |
| Diversity gain |
SNR improvement from combining decorrelated antennas (dB). Vaughan-Andersen: DG = 10·√(1 − ECC²). |
| Fade margin |
Extra link budget reserved to hold a target reliability under fading (Rayleigh / Rician). |
| Rician K |
Ratio of dominant (LOS) to scattered power in a Rician fading channel. |
| SFF |
System Fidelity Factor — normalized cross-correlation between transmitted and received UWB pulses. 1.0 = perfect; 0.95+ usually good. |
| setup_group |
A free-text tag on a cal-drift run identifying its methodology epoch (e.g. pre-2024-cable-change). Mismatch is flagged when comparing across groups. |
| TRP |
Total Radiated Power. Integral of radiated power over the sphere. IEEE solid-angle formula with $\sin\theta$ Jacobian. |
| Touchstone |
Industry-standard .s2p / .s1p file format for S-parameters. RFlect's UWB pipeline reads .s2p. |
| VSWR |
Voltage Standing Wave Ratio. Derived from S11 magnitude. 1.0 = perfect match; 2.0 ≈ -9.5 dB return loss. |
| WTL |
Wireless Telecom Lab — the chamber-output format RFlect's parsers were built against (V5.02 / V5.03). |
| XPD |
Cross-Polarization Discrimination — co-pol field divided by cross-pol field, in dB. Uses 20 log, not 10 log. |
| EIRP |
Effective Isotropic Radiated Power — power radiated in a given direction relative to an isotropic source. RFlect's per-angle chamber input; TRP is its sphere average (the 1/4π in calculate_trp). |
| Sidelobe |
A radiation lobe other than the main beam; sidelobe level (SLL) is its peak relative to the main-lobe peak, in dB. |
| Group delay |
−dφ/dω, the negative derivative of transmission phase w.r.t. angular frequency (s); flatness across the band matters for wideband/UWB pulse fidelity. |
| Cal drift |
Change in a chamber's path-loss calibration factors over time; RFlect tracks runs across epochs and flags drift beyond a threshold. |