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Passive Gain

Gain, efficiency, directivity, and polarization analysis from HPOL + VPOL chamber pairs.

Passive 3D pattern with turbo colormap

What you need

  • A WTL HPOL .txt file (*_HPol.txt)
  • The matching VPOL .txt file (*_VPol.txt)
  • Optional: cable loss in dB

In the GUI

  1. Scan type: Passive
  2. Set Cable Loss (dB) if applicable
  3. Ctrl+O and pick the HPOL file — RFlect locates the matching VPOL automatically
  4. Plots render: 1D gain/efficiency vs frequency, 2D azimuth/elevation, 3D pattern, optional datasheet plots

What you get

Metric Notes
Total gain (dBi) $10\log_{10}(
H-gain / V-gain Ludwig-3: HPOL → $E_\phi$, VPOL → $E_\theta$
Efficiency Spherical sin-weighted average gain
Directivity Peak gain − average gain
Axial Ratio / Tilt Angle / XPD Polarization-ellipse metrics (see Polarization)
Sense (RHCP/LHCP) From phase-difference $\delta$ between $E_\theta$, $E_\phi$

2D azimuth cuts

Passive 2D azimuth cuts

1D efficiency vs frequency

Passive 1D efficiency vs frequency

Datasheet output

Datasheet 1D plot

Math conventions

  • Ludwig-3 polarization — HPOL is $E_\phi$ (azimuthal), VPOL is $E_\theta$ (elevation). See plot_antenna/calculations.py:637.
  • dB averaging — convert to linear first: $10\log_{10}(\text{mean}(10^{dB/10}))$, then back. Never average dB directly.
  • Spherical average — sin-weighted to account for the smaller solid angle near the poles.

Batch / MCP

Process every HPOL/VPOL pair in a folder:

process_folder("/path/to/wifi_antenna", intent="passive", report=True)
# or restrict to specific frequencies:
process_folder("/path/to/wifi_antenna", intent="passive",
               freqs=[2400, 2450, 2500], report=True)

See Recipes.

CST export

Combine HPOL + VPOL + VSWR into a single CST Farfield Source file:

convert_to_cst(hpol_path, vpol_path, vswr_path, frequency=2450)

Common gotchas

  • HPOL/VPOL filenames must match. RFlect pairs them by prefix and the _HPol / _VPol suffix. validate_file_pair checks angle/freq alignment.
  • Cable loss is the same for both files. If H and V used different cables, you'll need to pre-correct the files.
  • Efficiency vs gain — efficiency is the spherical-average; peak gain is much higher than average gain for directive antennas.

See also