Pattern Formats

mcnanovna can import antenna patterns from several file formats.

CSV

Comma-separated values with angle and gain data.

3-Column Format (Full 3D)

theta,phi,gain_dbi
0,0,-40
0,10,-40
...
90,0,2.15
90,10,2.15
...
180,0,-40

Column	Description
theta	Polar angle (0-180°)
phi	Azimuth angle (0-360°)
gain_dbi	Gain in dBi

2-Column Format (Single Cut)

angle,gain
0,-40
45,-10
90,2.15
135,-10
180,-40

Single-cut data is synthesized to 3D using a sin(θ) taper.

Delimiters

Auto-detected: comma (,), semicolon (;), or tab.

Headers

Optional. If first row contains non-numeric values, it’s treated as a header.

EMCAR vna.dat

Format from EMCAR antenna range software.

# EMCAR antenna pattern measurement
# Frequency: 145 MHz
0 0.5
45 0.8
90 1.0
135 0.8
180 0.5

Column	Description
angle	Azimuth angle (degrees)
amplitude	Linear amplitude (0-1)

The gnuplot transform is applied automatically:

Angle: (-angle + 90) rotation
Gain: 20 * log10(amplitude + 0.01)

NEC2 Output

Output from NEC2/NEC4 antenna simulation.

                            - - - RADIATION PATTERNS - - -

  - ANGLES -               - POWER GAINS -         - POLARIZATION -
  THETA   PHI         VERT.     HOR.      TOTAL      AXIAL     TILT
 DEGREES DEGREES       DB        DB        DB        RATIO     DEG
   0.00    0.00     -999.99   -999.99   -999.99     0.00000    0.00
   5.00    0.00       -4.52   -999.99     -4.52     0.00000   90.00
  10.00    0.00        1.43   -999.99      1.43     0.00000   90.00

Polarization Selection

Option	Column
`total`	TOTAL (default)
`vert`	VERT.
`hor`	HOR.

The frequency is auto-detected from the NEC2 header.

Touchstone S1P

Touchstone S-parameter file with S11 data.

! NanoVNA measurement
# Hz S RI R 50
144000000 0.15 -0.08
145000000 0.02 -0.01
146000000 0.12 0.05

Formats

Option	Data Format
RI	Real, Imaginary
MA	Magnitude, Angle (degrees)
DB	dB Magnitude, Angle (degrees)

Processing

Find resonance (minimum |S11|)
Calculate impedance at resonance
Estimate antenna type from impedance
Generate analytical pattern

Antenna Type Override

If auto-detection is wrong, specify the type:

import_pattern_s1p(content, antenna_type="monopole")

Internal Format

All import functions return the same structure:

{
    "antenna_type": "dipole",
    "frequency_hz": 145000000,
    "theta_deg": [0, 5, 10, ...],  # List of theta values
    "phi_deg": [0, 10, 20, ...],    # List of phi values
    "gain_dbi": [-40, -35, ...],    # Gain at each point
    "peak_gain_dbi": 2.15,
    "num_points": 6552
}

This format is used by:

Web UI visualization
radiation_pattern_multi comparison
Export functions

Interpolation

For irregular measurement grids, IDW (inverse-distance-weighted) interpolation maps data to the standard theta×phi grid:

Theta: 0° to 180° in 5° steps (default)
Phi: 0° to 355° in 5° steps (default)

Great-circle distance is used for accurate angular weighting.