Quadriga-Lib: C++/MEX Utility library for radio channel modelling and simulations

Data Formats

Overview

QuaDRiGa Array Antenna Exchange Format (QDANT)

QuaDRiGa Array Antenna Exchange Format (QDANT)

<layout>	Defines how multiple <arrayant> objects are arranged into an object array (optional)
<arrayant>	Describes a single array antenna

QuaDRiGa Array Antenna Exchange Format (QDANT)

QDANT is an XML grammar for exchanging array-antenna pattern data. Tag names are case-sensitive. A file contains a single <qdant> root element that may include an optional <layout> and one or more <arrayant> elements. A namespace is required on the root (with or without a prefix).

Coordinate convention (for interpreting pattern data):

Spherical (polar-spherical) angles theta (elevation) and phi (azimuth).
Elevation theta: −90° (down) … 0° (horizon) … +90° (up).
Azimuth phi: −180° (west) … −90° (south) … 0° (east) … +90° (north) … +180° (west); counting is anti-clockwise.
Pattern components are resolved along unit vectors ê_theta and ê_phi (far-field, no ê_r component).

See related read / write functions in the API documentation for details on how to use this format:

C++ QDANT read function (qdant_read)
C++ QDANT write function (arrayant.qdant_write)
MATLAB / Octave QDANT read function (arrayant_qdant_read)
MATLAB / Octave QDANT write function (arrayant_qdant_write)
Python QDANT read function (qdant_read)
Python QDANT write function (qdant_write)

<layout> - Defines how multiple <arrayant> objects are arranged into an object array (optional)

Content:
- One or more column vectors, separated by spaces; entries within a vector are comma-separated.
- Values: Integers that must match the id of corresponding <arrayant> elements.
Examples:
- Linear list: 1 2 3 (three columns with one entry each).
- 3×2 matrix of object IDs (3 columns, each a column vector of length 2): 1,2 1,2 2,1

<arrayant> - Describes a single array antenna

Attributes:
- id (integer, required if multiple arrayants present)
  Unique values per file; if <layout> is used, each id referenced there must exist.
Child elements:
- <name> (string, optional)
  Human-readable identifier.
- <CenterFrequency> (Hz, integer or float, optional)
  Default 300 MHz if omitted. When omitted, element positions are interpreted in wavelength multiples (i.e., meters scaled by λ at 300 MHz).
- <NoElements> (integer, required for multi-element arrays)
  Number of elements in this array.
- <ElementPosition> (optional)
  One or more position vectors [x,y,z] in meters, relative to the phase center. Axis orientation: x = east, y = north, z = up. Formatting: Vectors separated by spaces; within each vector, components separated by commas. Requires <NoElements> to be defined and to match the number of vectors. Example: 0,0,0 0.05,0,0
- <ElevationGrid> (degrees, required)
  List of elevation samples (−90 … +90). Example: -90 -45 0 45 90
- <AzimuthGrid> (degrees, required)
  List of azimuth samples (−180 … +180; 0 points east; anti-clockwise positive). Example: -180 -90 0 90 180
- <CouplingAbs> (optional; only with <NoElements>)
  N×M absolute values of the coupling matrix. Column vectors separated by spaces; entries within a column are separated by commas. Dimensions must be consistent with NoElements = N. M is the number of antenna ports. Example (N=2): 1,0 0,1
- <CouplingPhase> (optional; only with <NoElements> and <CouplingAbs>)
  N×N phases (degrees) for the same matrix. Column vectors separated by spaces; entries within a column are separated by commas. Dimensions must be consistent with NoElements = N. Example (N=2): 0,0 0,0
- <EthetaMag> (optional)
  Magnitude in [dB] of the electric field aligned with the ê − θ vector of the spherical coordinate system. One line contains all azimuth values for one elevation angle. The order is given by AzimuthGrid (columns) and ElevationGrid (rows). If NoElements is greater than 1, an additional attribute <EthetaMag el="[no]"> must be provided. In the first example, the first line contains the values for the -90 degree elevation angle (down) and the last line contains the values for the 90 degree elevation (up). If there is no field in θ-direction, this XML-element can be omitted.
- <EthetaPhase> (optional; only with <EthetaMag>)
  Phase in [degree] of the electric field aligned with the ê − θ vector. One line contains all azimuth values for one elevation angle. The order is given by AzimuthGrid and ElevationGrid. If NoElements is greater than 1, an additional attribute <EthetaPhase el="[no]"> must be provided. EthetaPhase cannot be defined without defining EthetaMag first. If all phases are 0, this XML-element can be omitted.
- <EphiMag> (optional)
  Magnitude in [dB] of the electric field aligned with the ê − φ vector of the spherical coordinate system.
- <EphiPhase> (optional; only with <EphiMag>)
  Phase in [degree] of the electric field aligned with the ê − φ vector.
Validation & Formatting Rules (at a glance):
- Case-sensitive tag names.
- <qdant> must be present; it may contain 0 or 1 <layout> and 1+ <arrayant>.
- If <layout> is present, every integer in it must match an existing <arrayant id="…">
- If NoElements is provided:
  (1) ElementPosition (if present) must provide exactly NoElements vectors.
  (2) CouplingAbs and CouplingPhase (if present) must be N×N with N = NoElements.
  (3) Pattern tags (Etheta, Ephi) must include el="1" … "N" for per-element data.
- Pattern blocks: Number of lines = length of ElevationGrid. Numbers per line = length of AzimuthGrid. Magnitudes in dB; phases in degrees.
- Omissions: If a component is everywhere zero, omit its Mag (and its Phase). If all phases are zero, *Phase may be omitted.

Quick Reference:

Element	Required	Type / Units	Notes
`qdant`	Yes	–	Root; carries namespace
`layout`	No	int matrix (text)	Columns separated by spaces; within a column, IDs comma-separated
`arrayant@id`	Cond.	int	Unique; referenced by `layout`
`name`	No	string	Free text
`CenterFrequency`	No	Hz	Default 300 MHz if absent
`NoElements`	Cond.	int	Required for multi-element arrays
`ElementPosition`	No	meters	Vectors `x,y,z`; vectors space-separated; components comma-separated
`ElevationGrid`	Yes	degrees	−90 … +90
`AzimuthGrid`	Yes	degrees	−180 … +180; 0° east; anti-clockwise positive
`CouplingAbs`	No	matrix	N×M; columns space-sep; entries comma-sep
`CouplingPhase`	No	matrix (deg)	Requires `CouplingAbs`; same shape
`EthetaMag`	Cond.	dB grid	Rows = elevations; cols = azimuths; `el="n"` if N>1
`EthetaPhase`	Cond.	deg grid	Only with `EthetaMag`; omit if all zeros
`EphiMag`	Cond.	dB grid	Rows = elevations; cols = azimuths; `el="n"` if N>1
`EphiPhase`	Cond.	deg grid	Only with `EphiMag`; omit if all zeros

Example:
2-Element Cross-Polarized Array (minimal pattern values):

<?xml version="1.0" encoding="UTF-8"?>
<qdant xmlns="http://www.quadriga-channel-model.de">
  <layout>1</layout>
  <arrayant id="1">
    <name>Simple XPOL</name>
    <CenterFrequency>2600000000</CenterFrequency>
    <NoElements>2</NoElements>
    <ElementPosition>0,0,0 0,0,0</ElementPosition>

    <ElevationGrid>-90 0 90</ElevationGrid>
    <AzimuthGrid>-180 -90 0 90 180</AzimuthGrid>

    <CouplingAbs>1,0 0,1</CouplingAbs>
    <CouplingPhase>0,0 0,0</CouplingPhase>

    <EthetaMag el="1">
      0 0 0 0 0
      0 0 0 0 0
      0 0 0 0 0
    </EthetaMag>
    <EthetaPhase el="1">
      0 0 0 0 0
      0 0 0 0 0
      0 0 0 0 0
    </EthetaPhase>

    <EphiMag el="2">
      0 0 0 0 0
      0 0 0 0 0
      0 0 0 0 0
    </EphiMag>
    <EphiPhase el="2">
      0 0 0 0 0
      0 0 0 0 0
      0 0 0 0 0
    </EphiPhase>
  </arrayant>
</qdant>