A user-defined antenna (UAN) file contains antenna pattern information in text format that users can create and read for use in post-processing applications. The `*.uan` file format is unique to Remcom and ideal for sharing data across its suite of design and electromagnetic simulation products, including XFdtd^{®}, Wireless Insite^{®}, XGtd^{®}, WaveFarer^{®}.

## UAN File Structure

Although the `*.uan` file supports multiple formats, XF writes the complex output in one format only. The `*.uan` file begins with text concerning parameters. The theta-phi coordinate system provides definitions relative to the x-, y-, and z-axes.

The `format free` text line is of no significance to the file's content, but explanations for the remaining lines are as follows:

`phi_min`: minimum phi observation angle in degrees.
`phi_max`: maximum phi observation angle in degrees.
`phi_inc`: phi observation angle increment in degrees.
`theta_min`: minimum theta observation angle in degrees.
`theta_max`: maximum theta observation angle in degrees.
`theta_inc`: theta observation angle increment in degrees.
`complex`: data consists of complex numbers.
`mag_phase`: data is magnitude and phase.
`pattern gain`: quantity being stored is gain.
`magnitude dB`: data magnitude component is dB.
`direction degrees`: observation angles are specified in degrees.
`phase degrees`: data phase component is degrees.
`polarization theta_phi`: polarization for antenna radiation measurements.
`NetInputPower`: simulation's net input power in watts.
`ReferencePoint`: far zone pattern's phase reference point as x, y, and z coordinates in meters.

The parameters portion is followed by a data section that provides angle-based pattern data of one row per angle.

The following six variables correspond to the six columns in the data portion of the `*.uan` file:

\begin{eqnarray}
\theta\,\,\,\,\phi\,\,\,\,G_{\theta}(\theta,\phi)\,\,\,\,G_{\phi}(\theta,\phi)\,\,\,\,\angle{E_{\theta}(\theta,\phi)}\,\,\,\,\angle{E_{\phi}(\theta,\phi)}
\end{eqnarray}

where $\theta$ is the theta observation angle in degrees, $\phi$ is the phi observation angle in degrees, $G_{\theta}(\theta,\phi)$ is the theta polarized gain in dB, $G_{\phi}(\theta,\phi)$ is the phi polarized gain in dB, $\angle{E_{\theta}(\theta,\phi)}$ is the theta polarized E-field phase in degrees, and $\angle{E_{\phi}(\theta,\phi)}$ is the phi polarized E-field phase in degrees.

## Convert Gain to E-Field

E-field magnitude is not provided in a `*.uan` file, but it is determined by first converting gain in dB to linear units

\begin{equation}
G_{linear}=10^\frac{G_{dB}}{10}
\end{equation}

and then converting gain to E-field magnitude

\begin{equation}
|E|=\sqrt{\frac{G_{linear}\eta_0 P_{in}}{2\pi}}
\end{equation}

where $\eta_0$ is the impedance of free space and $P_{in}$ is the `NetInputPower` available in the parameters section of the `*.uan` file.